Diesel Engine Fundamentals (Part 2) | SaVRee 3D | Skillshare

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Diesel Engine Fundamentals (Part 2)

teacher avatar SaVRee 3D, saVRee.com. Where engineers go to learn.

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Lessons in This Class

64 Lessons (2h 55m)
    • 1. Course Overview

    • 2. Welcome To The Course

    • 3. Four and Two Stroke Engine Introduction

    • 4. Four Stroke Engine Cycle Revisited

    • 5. Four Stroke Engine Timing Diagram

    • 6. Four Stroke Engine Intake Stroke

    • 7. Four Stroke Engine Compression Stroke

    • 8. Four Stroke Engine Fuel Injection

    • 9. Four Stroke Engine Power Stroke

    • 10. Four Stroke Engine Exhaust Stroke

    • 11. Four Stroke Engine Cycle Summary

    • 12. Two Stroke Engine Cycle Revisited

    • 13. Two Stroke Engine Exhaust and Intake Strokes

    • 14. Two Stroke Engine Compression Stroke

    • 15. Two Stroke Engine Power Stroke

    • 16. Large Two Stroke Engine Timing Diagram

    • 17. Two Stroke Engine Cycle Summary

    • 18. Maintenance Strategies Introduction

    • 19. Types of Maintenance Strategies

    • 20. Reactive Maintenance

    • 21. Reactive Maintenance Pros and Cons

    • 22. Preventive Maintenance

    • 23. 24 Preventive Maintenance Pros and Cons

    • 24. Predictive Maintenance

    • 25. Predictive Maintenance Pros and Cons

    • 26. Reliability Centred Maintenance

    • 27. RCM Pros and Cons

    • 28. Maintenance Strategy In Action

    • 29. Thermodynamic Cycles Introduction

    • 30. Pressure Temperature and Volume

    • 31. Amontons Law

    • 32. Charles Law

    • 33. Pressure and Volume Diagram

    • 34. Diesel Gas Cycle

    • 35. Thermodynamic Cycles

    • 36. Power Cards

    • 37. Compression Diagrams

    • 38. Gas Cycle Summary

    • 39. Engine Protection Introduction

    • 40. The Importance Of Engine Protection

    • 41. Level Measurements

    • 42. Temperature Measurements

    • 43. Pressure Measurements

    • 44. Flow Measurements

    • 45. Overspeed Protection

    • 46. High Jacket Water Temperature

    • 47. Exhaust Gas Temperature

    • 48. Low Lubrication Oil Pressure

    • 49. High Crankcase Pressure

    • 50. Engine Protection Final Thoughts

    • 51. Engine Protection Summary

    • 52. Starter Circuit Introduction

    • 53. Starting Circuits

    • 54. Glow Plugs

    • 55. Engine Control and Governors Introduction

    • 56. Engine Control

    • 57. Fuel Injectors

    • 58. Governors

    • 59. Operation Of A Governor

    • 60. Simplified Operation Of A Governor

    • 61. How Centrifugal Governors Work

    • 62. Mechancial Hydraulic Governors

    • 63. Control Summary

    • 64. End Of Course

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About This Class

Mechanical Engineering Series - learn more about the diesel engine (internal combustion engine)!

Without exception, the reciprocating piston engine is the most influential machine ever invented by mankind. From its early beginnings as a steam engine, the piston engine has revolutionised the way we live, work and travel. This course will teach you more about this truly amazing machine.

You will learn about:

  • Detailed two stroke and four stroke cycles.

  • Detailed two and four stroke timing diagrams.

  • Thermodynamic gas cycles (Otto, Diesel etc.).

  • Maintenance strategies (breakdown, scheduled, predictive etc.)

  • How an engine is started (starter circuit).

  • Centrifugal and electrical-hydraulic governors.

  • What indicator and compression diagrams are.

  • Engine protection - how to protect using temperature, pressure, flow and level measurements.

  • And a lot lot more!

*** Note that this course focuses more on the diesel fired engine type rather than the petrol/gasoline type, but gives a general good overview concerning the internal combustion (IC) engine. The video is part of the Mechanical Engineering video series.***

The course is designed to build on the knowledge gained in the Diesel Engine Fundamentals course, although this course is also suitable to anyone who already has some diesel engine background knowledge.

The course is packed with 2D images, 2D animations and 3D animations.

Written content has been read aloud so that you can 'learn on the go' without needing to watch the screen constantly.

Don't waste more time reading this course description, check-out some of the lessons! I hope to see you on the course!

All the best,



Meet Your Teacher

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SaVRee 3D

saVRee.com. Where engineers go to learn.


saVRee produces high quality video courses for the engineering market. Our courses are taught by subject matter experts (SMEs) with years of experience in many different industries.

If you are interested in HVAC, Mechanical, Electrical, Automobile, Chemical, Power or Industrial Engineering, we have courses for you!

Courses are presented using interactive 3D models and 3D animations. The 3D models can be exploded into their parts and a cross section feature allows you to see exactly what is happening inside the machine.

We also read written content aloud so that you can learn 'on-the-go'

If you are a professional engineer, or a student preparing for entry into the exciting world of engineering, we guarantee you will find our courses of great benefit.

Jo... See full profile

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1. Course Overview: Why John here in this course, we're going to look in greater detail at the diesel engine. We're gonna look at precious volumes and temperatures and the relationships they have to each other. We're also going to look at thermodynamic cycles such as the auto Creighton on diesel gas cycles. We're gonna look at how we protect the diesel engine from situations such as lobe or pressure or high jacket water temperature will look at the alarms and shutdowns typically associated with a diesel engine will look at governors, centrifugal governors, electrical hydraulic governors. We'll discuss how they work, how we can control the speed off the engine. Using these governments, we look at the starting circuit associated with these. Ranging on I don't mean simple electronic circuits here. I also mean compressed their systems. So we look at the different ways that you can start a diesel engine and as a bonus, will look at maintenance strategies associating with diesel engines. Now these maintenance strategies can be applied to any engineering industry, the maintenance strategies. We are going to discuss our breakdown, maintenance, preventive maintenance, predictive maintenance, reliability, centred maintenance. I'm going to explain to you what exactly those terms are on the pros and cons associated with each of these maintenance strategies. So although the course is about a diesel engine on how it works with a lot more detail, we're also gonna learn a lot of things that you can apply to any engineering industry that you're likely to enter. So irrespective off, if you are a newbie, totally new to the engineering industry or if you're an old hand, I do recommend you check out some of the free preview videos with this course. And if you like videos thing, I hope to see you on the course. Thanks very much for your time. 2. Welcome To The Course: thanks very much for signing up to the course. I really do hope you get a big benefit from it. In this course, you're gonna learn a lot about the diesel engine. But you're gonna learn a lot about other things that you can apply to different engineering industries. So there is quite a broad spectrum of things. They're gonna be talked in this course, so keep that in mind. I know that you want to stay focused on a diesel engine, and that's all good. But I try in every course to promote learning in such a way that you can learn to learn. In other words, you should be able to look at machines in the future and apply some logic good engineering practices on. You should be able to discover them how the machine works well, what you should be doing to maintain it. What I want to try and avoid is a situation where people love my courses and they learn only in parrot fashion. That's not really learning. I want to be able to think through the problems and then solve the issue on that's what I hope this course will allow you to do I'm a big fan of feedback. So if you have any, please do send it trying continually improve these courses when I get around to them on. If you have time to leave a review afterwards, I would greatly appreciate it. Enjoy the course. 3. Four and Two Stroke Engine Introduction: so in the 1st 2 sections. Now what we're gonna do is discuss the four stroke cycle in more detail on the two stroke cycle. In more detail, there's gonna be a focus on pressure, volume and temperature on their relationships to each other on. The reason for that is because later on the course, we're going to talk about thermodynamic cycles gas cycles, and you'll see the importance off knowing the relationships between pressure volume on temperature on If you know those relationships, then you can then use that information and knowledge to work your way through problems in the future. So let's get on now on. Do the four stroke, two stroke engine cycles in war decell on. Then they'll be an update from me after those two sections are complete. 4. Four Stroke Engine Cycle Revisited: So this part of the course is about a four stroke engine, four stroke cycle. You may already know a lot about it, but it's a good refresher on. We're going to go into a lot more detail compared to in the first course we did, which only gives a very brief overview off each stage off the cycle. In next lesson, we're gonna have a look at a time in diagram because that's gonna be something that pops up for, of course. So I want to make sure that everyone knows how to read a four stroke engine timing diagram . But for now, let's just do a quick read through this lesson on. Then we'll get onto timing diagram. Listen. Four stroke cycle, the four straight. These ranging cycle consists of an intake compression power and exhaust stroke. Click on Image below to view a working four stroke engine cycle. I'm not gonna click on this, but access to the three D model is available. Just check your course materials and you should find a link to this three D model or you'll be able to access it directly through the website, a recommended due to stuff a local the parts and quick refresher on the part names and ensure you know exactly what you're talking about when you're thinking off a four stroke engine. But now, let's go on and have a look at the timing diagram on how we read a four stroke engine timing diagram. 5. Four Stroke Engine Timing Diagram: So before we start talking about the four stroke engine in detail and how it works, let me just introduce you to a four stroke engine timing diagram. Now this diagram represents the crank angle is the angle of rotation of the crankshaft. We've got the TDC, which is top dead center on BBC, which bottom dead center. The piston moves up and down as we go around, or as the crank is rotated in a clockwise direction. So keep that in mind. This round space here would be the crankshaft, so we had angular motion. That is to say, the crankshaft rotates in a clockwise direction. Where is the piston? Moves up and down towards doctor center and then back down again. I o means inlet open and I see means inlet closed E. C means exhaust closed and EEO means exhaust open. So we talk about the Air Inlet, which Blue blue represents here, and the exhaust hot exhaust gases, which are represented by the Red Easy and oh, what they're specifically pointing to along this line or along. All of these four lines are the exact points where the valves open and close. So Air Inlet Valve opens at the exact point here where the line is on the air Inlet closes again where the line is here. But let me show you how you can read the diagram. So let's imagine that we've just finished a combustion cycle and we need to draw fresh air into the cylinder so I piston's gonna come towards top dead center, since it is rotating around the crankshaft rotates around the business being pushed upwards on. Then, at this point here, the air inlet valve is going to open. It's then gonna drawer areas. The piston moves down on the crankshaft, rotates clockwise. Piston reaches bottom. Dead center comes around here. So we're looking about 200 degrees straight line. Vertical here is zero. So 180 to the lower straight line. About 200 or 210 here. So the area valves open. Open, open, open, open, closed. Okay, so 210 degrees. The air inlet valve has closed, so now we can see we've ended on. I see. Now we're gonna continue rotating around, but because we've drawn in the air, we're now compressing it as the piston moves up to top dead center. Gonna have this black thick bar going all the way across until about five degrees past top dead center. What? This is this is the period where we inject fuel on where we have combustion. So we're getting a controlled explosion in this sort of area here. So the pistons come up, It's almost adopted. Center. It's approaching top. Dead center. We're having our explosion on. Then he's going to start coming back down again. So with that in mind, it's actually, that's quite early. Normally have expected to be about here, maybe five degrees before or 10 degrees before Dr. Tender, it looks, looks a little more on this diver. But anyway, the point is, we start injecting fuel. We compress the fuel, it ignites. We get our explosion, Andi. Then what's gonna happen is that this explosion and increasing pressure is gonna push the piston back down again. Down, down, down on! Then what's gonna happen is the exhaust gas valve is gonna open because this whole section here was effectively our power strike. So they extracted the power. Power has been transferred to the crankshaft on then to our load exhaust gas valve opens. We push out the exhaust gas away is the piston comes up to talk dead center. So you were discharged in the exhaust gas pushing out up to talk to center on. Then what we're gonna do, Start drawing area in a roundabout Here on as the piston comes down again we're gonna draw fresh air in on the process repeats. So we're actually drawing fresh air in in this section here on the exhaust gas valves are open. That's effectively the scavenging period where we're going to try and get the exhaust gas out in the fresh air in. And then we'll close exhaust gas valve here and allow the air to be sucked in. A subsisting goes downwards on. Then we'll get a compression stroke again. So you intake compression and then injection. Combustion was explosion controlled explosion in this area expansion, which is also a power stroke. Andi, once we get out of power stroke, we're gonna have the exhausts, which is this section around here on. Then the process repeats. So that's a you read a four stroke timing diagram. Two stroke is a lot more simple because it's literally power stroke around here. Have a quick change valves to get the exhaust gas out on, get the Aaron on, then you're gonna compress it, and then you're gonna have an explosion that expansion on etcetera in the whole process repeats. So to stroke is 360 degrees of operation around the grand theft because it's two strokes, one down and one up and four stroke is down, up, down, up. So it's 720 degrees of rotation of the crankshaft. So now it's done. Let's have a look at this stage is off a four stroke combustion cycle in more detail. So next lesson is going to look at things like intake compression exhaust on. We're gonna explain exactly what's happening. We're gonna look at the temperatures and pressures related each stage off the combustion cycle, and hopefully you get much deeper understanding of exactly how the engine is working. 6. Four Stroke Engine Intake Stroke: in tight as the piston moves upward and approaches 28 degrees before top dead center as measured by crankshaft irritation, camshaft lobes starts to lift the camp follower. This causes a push rod to move upwards on fits the rock around on the rock around chef. As the valve last has taken up, the rock around pushes intake valve downward on the valve starts to open. The intake stroke now starts while the exhaust valve is still open. The flow of the exhaust gases will have created a low pressure condition were in the cylinder on will help pull in fresh air charge. A PSA piston moves towards bottom dead center. So this is a lot happening as part intake stroke. It's really free lesson. Then we'll go back through some of these points on our build on what's in the text. The piston continues its upward travel for a top dead centre while fresh air enters and exhaust gases leave at about 12 degrees after top dead centre, the camshaft exhaust love rotates said it the exhaust valve for start to close. The valve is fully closed at 23 degrees after top dead center, Full pleasure of The valve is accomplished through the valve spring, which was compressed when the valve was opened, forcing the rock Iran Andi Can follower back against the Cham lo as it rotates. The timeframe, during which both the intake and exhaust valves are open is called the valve Overlap. 51 degrees of overlap in this example on is necessary to allow the fresh air to help scavenge or remove the spend exhaust gases and call the cylinder in most engines 30 to 50 times cylinder volume. He scavenges through the cylinder during overlap. This excess cool air also provides the necessary cooling effect on the engine parts. As the system passes, doctored Center on begins to travel down the cylinder, bore the movement of the piston, creates a suction and continues to draw fresh air into the cylinder. Okay, so if we're looking doing a short summary on this paragraph, essentially, what's happening? This is that 28 degrees before Top Dead Centre, the Air Inlet valve, his opening on what we're going to get is a small amount of overlap because the air inlet valves gonna open on the exhaust gas valves are also going to be open so what we're gonna have these air being drawn in. An exhaust gas being pushed out on this process is known as scavenging. The bulk of the text here is simply to describe what's happening, such as the push rods being pushed up by the cam on, then the rock around. Being pushed down on this ultimately opens up the Air Inlet valve. So all of the timing associate with the engine, as discussed in the first course is controlled by the camp go down and could read the next paragraph As we're scavenging, the exhaust gas valve is actually an enclosed first. It's going to be fully closed at 23 degrees after top dead center, but we're going to continue to draw fresh air into the cylinder. In our example, we have 51 degrees of valve overlap, so that's the period where both the air inlet and the exhaust valves are open on. We can see that Rex is guarantee in 30 to 50 times a cylinder volume during the valve overlap period, so this is quite a large amount of air, but this ensures that we get rid of all of the exhaust gas on the way in fresh air and fresh oxygen into the combustion space. In order that we can get the maximum amount of power out of the engine, the business, and then continues on its way downwards. And as it does so, it creates a negative pressure within the combustion space on. We're gonna draw more fresh air into the combustion space, and that is our intake stroke. So it is quite a lot going on. We're creating the negative pressure of the piston moves down, withdrawing Aaron. Got the exhaust valves, also open a star off the stroke. They close again. Once we've scavenged and got all of the exhaust gas out of the combustion space. We keep drawing the Aaron on the piston, then travels along the way down the bottom dead center. It's gonna do a slight spin, and as it comes back up the other way, the intervals are going to close. Who will discuss that in the next lesson? 7. Four Stroke Engine Compression Stroke: compression at 35 degrees after bottom dead center. The intake valve starts to close at 43 degrees after bottom dead center intake valves on it , See? And it's pretty closed at this point. The air charges at normal pressure 14.7 p. S I at about 70 degrees before top dead centre. The piston has traveled about 2.125 inches for about half of its stroke, thus reducing the volume in the cylinder by half. The temperature is now doubled 260 degrees Fahrenheit. On the pressure is 34 p s. I Now, for some of your appreciate that P S, I and Fahrenheit might not be the normal units that you're working. So just try and take out the most important parts off each paragraph that we re through now they simply there as the piston starts to travel upwards towards stopped dead center about half of its stroke, it's reduced the volume in the cylinder by half because we traveled halfway up the cylinder on, the temperature has doubled, so keep that in mind is always a relationship between pressure, temperature and volume. So as the volume decreases, the pressure will increase, the temperature will increase on. Likewise, if the business moving downwards, the volume will increase, pressure will decrease on the temperature will decrease. If you compress something, temperature increases on. If something's allowed to expand, the temperature will decrease. Also know the 43 degrees after bottom dead center intake valve his fully closed on. That is the point at which we star compression cycle. You can even see Hear that both of the valves are closed. There's nowhere for the air to go. We're gonna compress it. The temperature's gonna increase on The pressure's gonna increase as well At about 43 degrees before top dead centre, the piston has travelled upwards 3.62 inches of its stroke on the volume is once again Haft . Consequently, the temperature again doubles to about 320 degrees Fahrenheit and pressure is 85. Peer soy. When the piston has traveled to 3.53 inches of its stroke, the volume is again hard on temperature Reached 604 degrees Fahrenheit on the pressure of 277 p. S I. When the piston has traveled to 3.757 inches of its stroke. All the volume is again Haft. The temperature climbs to 1280 degrees Fahrenheit and pressure reaches 742 p. S. I. With a piston area of 9.616 inches, squared. The pressure in the cylinder is exerting a force of approximately £7135 or 3.5 tons of force. So notice year that as the piston is traveling upwards were getting huge increases in both temperature on pressure. And that's what we have. A compression ignition engine. As we're compressing the gases within the combustion space, the temperature is becoming very high, and so is the pressure. If the pressure and temperature did no increases, we compress the gases. It would be impossible to have a compression ignition engine. It's this massive increase in temperature and pressure, specifically temperature, that allows us to inject the fuel and to get a fishing combustion. The above numbers are ideal and provide a good example of what is occurring in an engine during compression. In an actual engine, pressures reach only about 690 peer site. This is due primarily to the heat loss to the surrounding engine parts. So I think the important things take away from this lesson are that the compression stroke consists primarily off the closure off the air intake valve at about 40 degrees after bottom dead center for 43 degrees after bottom dead center. And from that point onwards, we are just compressing the gases and get in a huge increasing pressure and temperature onda a decrease in volume and that is essentially what's happening during the compression stroke. 8. Four Stroke Engine Fuel Injection: fuel injection. Fuel in a liquid state is injected into the cylinder, a precise time and rate to ensure that the combustion pressure is forced on the piston, neither too early nor too late. If you'll enters the cylinder where the heated, compressed there is present, however, it will only bone when it is in a vaporised state, attained for the addition of heat to cause vaporization and intimately mixed with the supply of oxygen. The first minute droplets of fuel into the combustion chamber, and I quickly vaporised the vaporization of the fuel courses yes, around in the fuel to cool, and it requires time for the air to reheat efficiently to ignite the vaporised fuel. But once ignition has started, the additional heat from combustion helps to further. They prize the new fuel entering the chamber as long as oxygen is prison. Fuel injection starts at 28 degrees before top dead center and ends at three degrees after top dead center. Therefore, fuel is injected for a duration of 31 degrees. What's interesting to notice here is that fuel is injected 28 degrees before top dead centre. Now that is quite surprising because if we inject the fuel before top dead center and it starts to combust. And realistically, we're gonna push the piston back in the opposite direction, a direction that we wanted to go. So it's only the momentum of the piston that gets it past top dead center on, then allows it to move back down the opposite side. In other words, in a clockwise direction when the fuel has combusted. If the fuel combusts too early, then all of our power stroke is going to be used to drive the piston the wrong way. But what actually happens is the other pistons on the way of the engine components, which already emotion will push the piston toward stop dead center and then back down again . Unfortunately, we didn't get much power out of this whole process when we actually call this knocking, that's what happens when your engine is knocking. The fuel combusting too early, and you're wasting all of that power that you should be extracting and sending to the load . However generally, if you inject the fuel before top dead center. By the time the piston has reached TDC, fuel would just start to ignite or shortly before about five degrees before TDC, the fuel suddenly combust and all of that power will then be transferred to the piston as it rotates back downwards towards bottom dead center. So we're not wasting any power. However, like a safe, it ignites too early and we're going to get knocking on all of that power that we should have extracted incented load. Who's gonna be wasted? What's also interesting is as we inject the fuel, what's actually occurring first is that we inject it. A fuel vaporizes, which means it changes state from a liquid to a vapour on. Because of this change of state, we actually get a temperature drop. And this is what allows us to inject the fuel At 28 degrees before top dead center, we get a short cooling effect as the fuel is a prize. But then obviously the fuel combusts on. It makes combustion of the other fuel entering into the combustion space a lot more efficient on quicker on. All of that is happening in literally a fraction of a second, so 28 degrees fuel injection starts the initial amount. Feel this injected it vaporised that cools down the surrounding areas slightly for a fraction of a second. Then it combusts the fuel. Then the remaining fuel is injected, also combusts on by the time we get to three degrees after top dead center where then having the explosion. It's well underway and we're pushing a piston down on. We're beginning our power stroke. The total fuel injection period is only 31 degrees in total, so it's a very short part off the four stroke cycle, literally only about four or 5% off the entire four stroke cycle. 9. Four Stroke Engine Power Stroke: power strike at the start of the power stroke. Both valves have closed. The fresh air charges being compressed on the fuel has been injected into starting to burn after the piston passes. Doctored center heat is rapidly released by the ignition of the fuel, causing a rise in cylinder pressure. Combustion temperatures are around 2336 degrees Fahrenheit. This rise and pressure forces the piston downward on increases to force on the crankshaft for the power stroke. So we can see here. We gotta power stroke on much as before for the compression stroke. We've got both of the valves closed, but instead of the pistol moving upwards, it's now moving downwards. So that is that power stroke. The energy generated by the combustion process is Noel harnessed in a two stroke diesel engine. Only about 38% of the generated power is harnessed to do work. About 30% is wasted in the form of heat rejected to the cooling system. About 32% in the form of heat is rejected out the exhaust. In comparison, the four stroke diesel engine has a thermal distribution of 42% converted to useful work 28% he rejected to the cooling system on 30%. He rejected how the exhaust So we can see that for a two stroke diesel engine, only 38% off the total power generated use turned into useful work, whereas for four stroke and she's 42%. So that's a 4% difference, which is colossal. When you think how often the engine might be operating, Let's say 4% Let's say even perhaps 5% 5% to me. Sounds like a lot. That's 1/20 of all the work done by the engine, so that is a very large amount. Imagine you're about to travel 1000 kilometers in your car. Well, if someone told you you were going to use up 4% more fuel with one engine with another, you'd probably be much more likely to choose. But one engine. It's more efficient. Notice also that there's 2% MAWR heat that is lost on the two stroke engine to the exhaust than there is on a four stroke engine. And that is simply because on a four stroke engine here we have 30% and there we have 32 the four stroke engine is able to control how much exhaust gas exits through the cylinder on. The timing is a lot more specific with a two stroke engine. This isn't the case. Timing is less specific on. Therefore, we can't control so much when the exhaust gas valves are closed in very large to strike engines. You can do that, however, In small two stroke engines, there is simply no valves, so we don't really control when or how the valves are closed. With a four stroke engine, we can couple the camps after the crankshaft, using gears or a chain. And this allows us to open and close of ours at specific times rather than just opening and closing or covering an opening the exhaust on Air Inlet ports. So this he lost through the exhaust and also to the cooling system is one of the reasons that the four stroke engine is simply more efficient than the two stroke engine. It's gonna look now the final part off the stroke. That's the exhaust stroke 10. Four Stroke Engine Exhaust Stroke: exhaust as the piston approaches 48 degrees before bottom dead center. The camera of the exhaust loads starts to force the follower upward, causing the exhaust valve to lift off its C. Due to the pressure difference between the combustion space and ambient air, the exhaust gases flow out of the exhaust valve and into the exhaust manifold. After passing bottom dead center, the piston moves upwards on, accelerates to its maximum speed at 63 degrees before top dead center. From this point, piston is decelerating As the piston speed slows down, the velocity of the gas is flowing out of the cylinder creates a pressure slightly lower than atmospheric pressure. At 28 degrees before top Dead centre, the intake valve opens and the cycle starts again. That is our exhaust stroke. We can see here that the piston is traveling upwards. Linearly. Crankshaft is rotating. We're gonna push out our exhaust gases out off the exhaust gas valve on a 28 degrees before top dead center, we start the whole process again. Where the air inlet valve opens, we draw in the fresh air. We have, ah, 50 degrees of valve overlap or 51 degrees. Whatever it was, we change the volume of the cylinder 30 to 50 times in order to ensure that all the exhaust gases out of the cylinder. Then we close the exhaust gas valve on the process continues so that it's a detailed look at the four stroke engine cycle. If you're not used to using degrees for bottom that center and top dead centre, etcetera, I suggest to try and get used to using them. They're actually quite useful. Personally, I don't do it in the same manner that we've discussed in the text year, 48 degrees before bottom that center, etcetera. Normally, I just imagined that the piston is split up in 720 degrees on. I'll ever explain it from a 360 degrees perspective, or I'll add on the 360 degrees so I could say, for example, 580 degrees, blah, blah, blah happens. It all depends on how you want to look at it. But the most important thing is that you realize roughly where on the diagram of these valves were opening and closing on, you can give some approximations for the degrees on where the valve overlap would occur. I'm always a big fan of understanding something rather than just memorizing it. And I think if you can draw out rough timing diagram irrespective of the angles and knowing what the angles are, then you're well on your way to understanding the concept on its A lot more important to understand the concept that is just too regard to take numbers and facts and figures in parrot fashion. Let's now get on with next lesson. We're going to start to look at the two stroke engine cycle on. We're going to look at it in the same level of detail as we have with the four stroke engine cycle. 11. Four Stroke Engine Cycle Summary: So let's just do a quick recap here. Fundamentals off the diesel cycle. Summary ignition occurs in a diesel engine by injecting fuel into the air charge, which has been heated by compression to a temperature greater than the admission point of the fuel. But these engine converts the energy stored in the fuels chemical bonds into mechanical energy by burning the fuel. The chemical reaction of burning the fuel liberates heat, which causes the gases to expand, forcing the piston to rotate the crankshaft. A four stroke engine requires two rotations of the crankshaft to complete one cycle. The events occur as follows intake. The best um passes top dead centre being take valves open on the fresh air is admitted into the cylinder. Exhaust valve is still open for a few degrees to allow scavenging to occur. We're actually gonna scavenge 30 to 50 times the volume of the cylinder, so it's quite a lot of there. It's being used to pass through the cylinder, called the combustion space Down on. Also ensure we're getting fresh air and fresh oxygen into the combustion space for the next combustion cycle. Compression. After the basement passes bottom dead center The intake valve closes on the piston travels up to top Dead center. That's the completion of the first crankshaft rotation. Fuel injection As the piston nears Doc Dead center on the compression stroke. The fuel is injected by the injectors and the fuel starts to burn. Further heating the gas is in the cylinder. How the piston fast stop dead center on the expanding gases Force of piston down rotating the crankshaft exhaust as the feast on passes bottom did censor the exhaust valves open on the exhaust Guess who start to flow out of the cylinder. This continues as the pistons travels up to top Dead centre pumping misspent gases out of the cylinder, a top dead centre. The second crankshaft irritation is complete. So during the exhaust beard, we're also gonna get a massive drop in pressure on a slight drop in temperature as all the exhaust gas flows out of the combustion space and saying with power stroke, as we continue the Paris trope, we're gonna get huge increase in pressure and temperature. But that's gradually gonna decrease as the piston travels down through cylinder concerning compression, a massive increase in pressure and temperature reduction in volume on its This increase in temperature is going to allow us to inject fuel and get good combustion or efficient combustion. 12. Two Stroke Engine Cycle Revisited: the two stroke cycle. Like the four stroke engine, the two stroke engine must go through the same four events in take compression power and exhaust. But a two stroke engine requires only two strokes of the piston to complete one full cycle . Therefore, it requires only one rotation the crankshaft to complete of cycle. This means several events must occur during each stroke for all four events to be completed in two strokes, as opposed to the four stroke engine, where each stroke contains roughly one of them in two stroke engine. The camps after is good, so that rotates at the same speed is the crankshaft Oneto one. The following three lessons will describe a two stroke supercharged diesel engine having intake ports and exhaust valves with a 3.5 inch ball on foreign stroke with 16 to 1 compression ratio as it passes 31 complete cycle. We will start in the exhaust strike all the time in marks given a generic, and we're very from engine to engine two. If the terms intake, compression power and exhaust seem alien to you and difficult to remember, try socks. Squeeze bang low. The process is the same so we're talking about Here is two standard two stroke engine Compared to the four stroke engine, there's only half a mini strokes of thing that's fairly obvious. The four stroke engine is quite easy to describe because each stroke correlates to one part off the combustion cycle, such as intake, compression, power or exhaust. Whereas on the two stroke engine we don't have this one straight per part of the combustion cycle, so there's no correlation. There is such, So I timing diagrams gonna look slightly different. Interesting to note, though, that the camshaft is geared, so they rotated the same speed as a crankshaft with a four stroke engine. That's not the case. The camshaft excuse of a rotates at half the speed of the crankshaft on that, then keeps in time with the crankshaft. You can ignore the bit here about the 3.5 inch bore and foreign stroke with 16 to 1 compression ratio within. That's a bit too much information. What we want to learn in this part of the course is simply Maura, about each off the stage is off the combustion engine cycle on, then we can focus on things such as the temperatures, pressures, volumes and other aspects that are changing during the combustion cycle. I think no in the inches on how far the piston has traveled is slightly too much information, so we will work instead, use in crankshaft degrees of rotation. 13. Two Stroke Engine Exhaust and Intake Strokes: exhaust on intake at 82 degrees after top dead centre with the piston near the end of its power stroke, the exhaust can begins to lift the exhaust valves. Follower. The valve lashes taken up on nine degrees later, with 91 degrees after top dead center, the rock around forces the exhaust valve off its see on the exhaust gases discharged from the cylinder into the exhaust gas manifold. As the exhaust gas is discharged, cylinder pressure starts to decrease after the piston travels 3/4 of its stroke towards bottom dead center or 132 degrees after top dead centre crankshaft rotation. The piston starts to uncover the inlet ports as the exhaust valve is still open. The uncovering of the inlet ports. Let's a compressed fresh air into the cylinder and helps cool the cylinder and scavenge cylinder of the remaining exhaust gases commonly in taping exhaust, occur over approximately 96 degrees of crankshaft. Rotation at 43 degrees after born dead center, the camera chef starts to close the exhaust valve at 53 degrees after bottom, dead center or 117 degrees before top dead center. The camp shaft is rotated sufficiently to allow the spring pressure to close the exhaust valve. Also, as the piston travels past 48 degrees after born, dead center or five degrees after the exhaust found starts closing, the intake ports are closed by the piston. Okay, so it's quite off information there. But let's have a look of the diagrams because I think this explains the whole process quite well. On weaken. Talk about the degrees of rotation as well. So here with uncovered are inlet ports noticed on to strike engine. We're not using valves to control the Air Inlet. This could arguably be quite a large two stroke engine on smaller engines. You are only ever gonna have ports so you can have an inlet poor on nick Source. Poor on the type of scavenging arrangement that you have, maybe loop or cross flow. This type of scavenging arrangement is called unit flow, where the exhaust gas valves amounted at the top of the combustion space on. Then we've got ports allowing here into the combustion space, so that allows their compressed air in. And that's called union float. So here we've got ports on the side. The air is allowed in. And then we're gonna cover up the ports of second stage. We're going to compress the air, increases temperature, reduce the volume, increase the pressure. Then we get our fuel injection andare ignition on. We start power stroke, which forces the piston back down again. Notice that we have no control really about when the inlet ports are uncovered. So whereas before we could sort of arrange the valves, the air intake valves and exhaust gas valves so that they open at precise intervals here when we use imports, we don't get that. We can only close off the Internet poor as the piston gradually moves up. Whereas if we use in a valve, weaken suddenly close the inlet poor, so the timing is much more precise. So let's load up their time in diagram and we can have a look on the timing diagram How the two stroke engine is working specifically for the exhaust and intake strokes. So here we are. We can see that 82 degrees after top dead centre, the piston news the end of its power stroke. So that occurs quite quickly before we even get to 90 degrees of crankshaft rotation. So It's quite a small power stroke. The exhaust can begins to lift the exhaust valve. Follower on the valve lashes Taken up the valve lash is the gap between the rock Haram and Top with the valve. So we're going to take that up. There's normally is like get to allow the thermal expansion of the parts, and then nine degrees later, the rock around forces the exhaust valve off its See Onda. We allow the exhaust gases to escape, and then we're gonna get a massive drop in pressure on also a slight drop in temperature. The temperature dropped comes mawr when we open our Air Inlet ports and that happens 100 32 degrees after top dead center of crankshaft rotation. So now we're taking in air with cooling down. A combustion space year is flowing straight out of the exhaust gas Sports on were beginning to scavenge. In other words, we're beginning to replace the exhaust gas with fresh air that has fresh oxygen, which we can use the combustion. I concede that intake and exhaust occur over approximately 96 degrees of crack chef rotation, so about 1/4 of our two stroke engine combustion cycle is dedicated to scavenging on less than 1/4 dedicated to the power stroke. And in the next section we begin to shut the Air Inlet ports in the exhaust valves on. Then we're gonna get a compression stroke, followed by fuel injection on, then combustion on. The process repeats. So that's an in depth look at the exhaust and intake strokes associated with two stroke engine. 14. Two Stroke Engine Compression Stroke: compression strike after the exhaust valve is on its seat, or 53 degrees after top dead centre, the temperature and pressure begin to rise in nearly the same fashion as in the four stroke engine. The blow image illustrates the compression in a two stroke engine 23 degrees before top dead centre, the injector camp begins to lift the inject. A follower on Bushrod Fuel injection continues until six degrees before top dead center. That's 17 total degrees of injection. So much the same as a four stroke engine. Rapid increase in pressure, rapid increase in temperature. Inject the fuel on as we injected it. It's gonna be vaporised on. Then we're waiting for it to combust on assumes that occurs. The rest of the fuel that's being injected would also burn on. Then we'll start a power stroke 15. Two Stroke Engine Power Stroke: power strike. The power stroke starts after the piston passes stopped its center. The blow image illustrates the power stroke, which continues until the piston reaches 91 degrees after top dead center, at which point the exhaust valve starts open on the new cycle begins. So it is a power stroke. We're now looking at the right side image on. We're gonna get out. Controlled explosion. These vows actually closed at the top. Although that looks like there's a slight gap. Andi, the massive increase in pressure on temperature is gonna push that piston downwards on. It's gonna go all the way down to approximately 90 degrees or 85 degrees after top dead Center on that is effectively power stroke. And that being completes the entire two stroke combustion engine cycle. So I just members a rough approximation. We're going about 90 degrees associate with power stroke, about 90 degrees. Associate it with scavenging on, then the rest is associated with compression on about 20 or 30 degrees. Associate ID with the injection on ignition. If you remember approximately those values and you can draw them roughy on a time in diagram, then you've more or less understood the whole concept associated with a two stroke engine timing diagram 16. Large Two Stroke Engine Timing Diagram: Let's have a very quick look at a large engine. Two stroke engine timing diagram. It's a slightly different diagram to a smaller to strike engine timing diagram. But I will explain to you why in a moment can see we've got the compression strike that starts number one. We're gonna compress all the air that's just been drawn in. We're going to start to inject the fuel. We're gonna get combustion. We're gonna get a massive increase in pressure, and temperature will get a power stroke or expansion stroke change over some valves in sections 4 to 5. Then we're going to scavenge again. About 90 degrees of the total time in diagram will get some valve change over again on the process continues. This diagram is slightly different from a smaller two stroke engine timing diagram because the fuel injection actually occurs later. The combustion part off the timing diagram last slightly longer on. We can see also year that the power strike it is roughly about 90 degrees, so it's a few degrees mawr than with a smaller two stroke engine. This valve changeover period from four and five is the period where we begin to open the exhaust gas valves on. We uncover the air Inlet poor, and then we scavenged all the way around again, about 90 degrees or 85 degrees in total on. Then we change over the flowers again. In this case, it's just to be one form or exhaust valves because we using Air Inlet ports on. Then we'll start the compression strike again so you can see it's very similar to a smaller two stroke engine timing diagram or has some slight differences. As said before, those just remember about 90 degrees for the power stroke, about 90 degrees for the scavenger empire on about nine degrees for compression, although it's actually slightly more on the rest, you can just associate with valves changing and fuel injection and combustion. If you get those degrees and this image roughly in your mind, then you're not gonna go far wrong when you're drawing out Timing diagram. The fuel injection itself is always gonna be very close to top dead centre, because if we start injecting fuel earlier, then the combustion process is gonna take longer. Maybe the fuel will ignite earlier on instead off pushing the piston down and rotating clockwise. We're actually gonna rotate the crunch have counterclockwise, and obviously this just takes away all the energy that we've created from the other pistons . 17. Two Stroke Engine Cycle Summary: two straight engine fundamentals of the diesel cycle. Summary. A two stroke engine requires one irritation to the crankshaft to complete one cycle events occurs, follows in take. The pistol is near bottom, dead center and exhaust is in progress. The intake valve. All ports open and the fresh air is forced in exhaust valves. Reports closed and intake continues. Compression. After both the exhaust and intake bowels or poor to closed, the piston travels up towards top dead center. Fresh air is heated due to compression fuel injection near top. Dead centre. The fuel is injected by the injectors and the fuel starts to burn. Further heating. The gas is in the cylinder. Power. The piston passes top dead center on the expanding gases. Force a piston down, great tasting, the crankshaft exhaust as the piston approaches. Born dead center, the exhaust fouls airports open on the exhaust gases discharged from the cylinder. So that is that two stroke engine cycle summary. Don't think I need to go to much more into that. If you get a chance dry and draw a four stroke in a two stroke engine timing diagram. See if you can do it roughly or approximately. And if you can, I think that's more than enough for this less than I think you understood at every time in diagrams on how to apply them to engines in order that you can understand where the piston ease in relation to where the crankshaft is. On the next part. Off the course, we're gonna look at maintenance associating with diesel engines. 18. Maintenance Strategies Introduction: So now we're gonna talk about maintenance strategies. Name might be wondering, What's that doing in this course? And that's a fair question. The reason I wanted to include in his course is because it will enrich your own engineering career, guaranteed your respective off where you're working or what industry you're working in. If it's related to engineering, you will need to know, or at least your benefit greatly from a bit of knowledge concerning maintenance strategies . When I found out about making it stretches use, it was a bit later on in my career on all of a sudden, everything seemed to make sense, at least in that direction of mating strategies. But unless someone tells you about these things is kind of difficult to piece it together. So what I'm gonna try and do in this next section is explained to you why we have maintenance strategies on why there has been a shift recently from one type making strategy to another On hopefully, by the end of it, you'll be able to say OK, so I understand that now I understand the reasoning on guaranteed when you're working on a day to day basis. If you're working for a large company were in a large industrial plan. You will see changes occurring on you will know in the back your mind the reason behind these changes, so it's quite useful information. You can skip this section if you want to. That's probably fired. Next bit is also one of diesel engine, but you'll see the relationship to this section has to diesel engine as well as to pretty much every other industry you're likely to work in with engineering, so let's get started. 19. Types of Maintenance Strategies: So in this part, of course, actually want to take a slight deviation away from diesel engines and give you some background knowledge into maintenance plans on maintenance strategies. The reason I want to do this is because personal find it enriches your own career. If you know a little bit more about the reasoning behind why machines are maintained on why specifically there maintained in the manner that they maintained in, for example, 100 years ago, you wouldn't have been changing oil filters or anything like that. In fact, they didn't have anything like that at the time. On this concept of protecting the machinery by filtering out particles or perhaps installing really fouls and things like that that simply didn't exist, the mentality was no there. And I'm gonna explain to how things have progressed over the past 100 years or so you can see here. We've got types of amazing these programs. We've got what's called at bath tub curve. That's this item here. Well, this line and on the X axes we've got the time and on the Y axis, we've got the failure rate now. In the past, they used to install a machine they were put into operation on. Typically, you would have a failure rate that followed this line here. That meant that as time progressed, the machine would gradually wear out on one of the components would fail. Sometimes the entire machine would fail catastrophically. And as you can see, as time progresses, this fairly rate increases. And this was quite typical for things like boilers used to operate them. And then they just continue operating them until eventually the boiler exploded Andi. Then people would die and install a new boiler. So back in the day, that was the way things were done. Obviously, nowadays, this is simply not acceptable. Some of the largest companies that exist now for surveying boilers and things like that they exist because they were born during this period in the 19 hundreds, when boilers will literally blowing up all the time on. At some point, somebody turned around said, Look, this is simply not acceptable. No, I only weekends a loss of life, but we're also getting the loss off revenue. Perhaps back then, that was even the deciding factor that low add unplanned shutdowns, and it costs too much money. Nowadays, it's the other way around. A loss of life is far more important than any loss off revenue. So that was the yellow dotted line here, and that's the way things used to be. We also call this maintenance strategy a running to destruction, illiterate stolen machine and in your wait until it dies or stops working. Another common failure pattern was this red dotted line here, the early infant mortality failure. And that meant that the failure rate was very high when you first put the machine into service. But as time progressed, the failure rate decreased. So this used to happen quite a lot when manufacturing standards were very vague. Or perhaps there was no Q and A, for example, so there's no quality assurance or testing off components that would install the components or the machine, and it would simply fail on then there to replace the machine and run it again. Maybe that one would fail as well. Eventually, the 3rd 1 in on this one runs okay, and it would continue along its useful working life until here on at some point it would also fail. However, normally what you get is a combination off both of these red and yellow lines, and you'll have something called the observed failure rate. That means as time progresses, failure rate decreases because the machine it didn't fail, it starts, so it looks like this fell. Now maybe it's already done 1000 cycles, etcetera, so you'll continue on its way along the blue line. You don't get to hear, and at that point the probability of failure begins to increase. Because the machine is getting older, components are beginning to wear down on the fairly rate will increase again. On this is our bathtub failure curve or a bathtub curve. And if you ever look reliability studies and things like that failure modes or failure mode analysis and F makers or FMC A's failure mode cause and effects, then you're going to see a lot of curves like this, or perhaps sometimes like this. Not so much nowadays, on not so much like this, either. Unless you're operating with a run, the destruction maintenance program can see we've got one of the Green Line year, and that is four constant random failures. So there's different ways that machinery from fail. Sometimes it might fail. It starts. Sometimes it might fail just because it's getting older. But what's really interesting is that as time has progressed, what people have tried to do is get rid off this strong line, sloping downwards. Get rid of this strong line, sloping upwards on. Just maintain a line such as this and push that line as far down on the graph is possible. Sometimes what you see is a line that comes up like this on the reason that it's slightly spiked as it goes along. The graph is because as time has progressed, people have performed maintenance on when they perform the maintenance, the probability of failure decreases again on we re set it back down to that low failure rate. This isn't always true, and I'll explain why in the next few lessons. But that's the general idea. So that's a bathtub failure curve. Let's just go down and read some of what's gonna be in the next few lessons. This course will discuss common maintenance programs currently employed in Engineering World. You will learn about breakdown or reactive maintenance, preventive maintenance, predictive maintenance on reliability, centred maintenance or RCM. We'll also learn about the advantages and disadvantages use associated with each type of maintenance strategy on current trends concerning which means mean strategies are becoming more popular or unpopular. So breakdown maintenance. This is the run it until it breaks will run into destruction mentality. You literally install it on. Then it will run until it fails. Preventive maintenance, also called scheduled maintenance or periodic maintenance. That's where you'll go in and maintain a machine periodically based on the number of service hours or a set period of time. Such a six months or 12 months. And your perform certain maintenance tasks in order that you reduce the probability. Oh, failure. That's preventive maintenance. Predictive maintenance is where we try and predict when failure will occur. Now we can do that by measuring things such as the temperature pressure level of vibration , ultrasonic tests, nondestructive testing. Etcetera will get into that in more detail later on. It's a very exciting field that's come through a lot in the past 10 years, and it's now beginning to dominate many plant maintenance strategies. Reliability centred maintenance is considered the absolute king of all maintenance strategy types. It's a type of making a strategy that looks at every machine, individually assesses its criticality on then matches a maintenance strategy to that specific machine. So, in summary, if we've got a motor that is 100% critical to the entire plan, such as a cooling motor, a motor associate with the cooling pump for nuclear power station if there was only one which isn't gonna be likely. But if there was, it would be very well maintained because it is absolutely critical to the entire process. The last thing we want is a nuclear meltdown just because the cooler water pump bearing failed or seized. So that's what reliability centred maintenance is. We're looking at the most important aspect of a process, the most important machines on. Then we're maintaining those first, and then we're spending more money on those machines to maintain them than the less critical machines. That's what we're gonna look at next. Few lessons on. We'll see how that relates to the diesel engine as we're moving through the lessons 20. Reactive Maintenance: reactive maintenance, reactive maintenance, a k a. Breakdown. Maintenance is the running until it breaks maintenance strategy. No actions or efforts are taken to maintain the equipment. Recent studies indicate that this maintenance mode is still the predominant mode of maintenance for many plants. The reference study breaks down the average maintenance programme as follows 55% reactive, 31% preventive, 12% predictive and 2% other Know that more than 55 cents off maintenance resources and activities of an average facility are still reactive. I've got to say here that I'm very surprised with this statistic simply because I used to travel around the world visit. In many industrial plants, biodiesel plans, oil see plants, mining facilities, power stations and most of the time, they were employing ivory, preventive or predominantly preventive or they were changing over to a predictive maintenance strategy. 55% reactive or breakdown Strategy seems to me to be quite high now. The logic behind this is simple. If you have a lot of machines in a process breaking down randomly, then there's a danger that you might interrupt the process. If you're making $20 million a day a specific plan, then the last thing you want to do is shut down the plan just because a few pumps have failed. If you shut down the plant for its imagine 12 hours and you're gonna lose $10 million now, the price of the punk maybe $200,000 might be $20,000. But the point is, your losses far far exceed the cost of having a spare pump on site or installing to bumps and changing from one to the other or maintaining upon in the first place. So that's one of the deciding factors that shifting people away from reactive or breakdown maintenance on towards preventive on predictive maintenance. As I say, though, in some other facilities where cash is no king, then perhaps they're still using this 55% reactive maintenance strategy. But at the end of the day, normally, if things cost more money than people tend not to want to do them. And that's the reason why the shift over to a different maintenance strategy advantages used to reactive maintenance could be viewed as both negative and positive if dealing with new equipment. Initial failure rates are low if the maintenance programme is purely reactive. Plant personnel will not expend manpower dollars or incur capital costs until something breaks. Since there are no initial maintenance costs, this initial period is sometimes classed as the saving money period. In reality, savings experienced during this period are often negligible compared to deter cost experience. Later, labor costs associate with any repairs and likely to be higher than normal because the failure will require extensive prepares compared to typical maintenance on the failure is also unscheduled. Since the equipment is operated until failure, a large inventory of spare parts is required. This is a cost that could be minimised under a different maintenance strategy. The largest cost, maybe associate with interruption to the process as a whole is cost is turned on the business interruption or downtime on his primary concern for most commercial plants. So this is all true. Imagine that we're operating the entire plan on a reactive or a breakdown maintenance strategy. This is really not good. We're gonna have random pieces of machinery failing. They're gonna fail randomly. We're never gonna know when they're gonna fail. We're gonna have to keep a huge amount spare parts on site as well as perhaps entire machines, and that is all additional costs. Many plants look at their spare parts and considerate dead money, spare parts, annoying service there. No making the plan, any money. And they may never be used. So they will look at this, and then they look at the cost of all of these spares on. Then they'll calculate roughly how much dead money they have sitting there. And if it's too much, they may even start to sell off the spares, which is gonna make the problem even worse when the machines do fail on despairs and no longer there. So all in all this reactive or breakdown may from the strategy is simply outdated. And this is why you will not see it used for things like these lynchings or emergency generators or anything like that. That is the reason why we changed filters on engines on why we conduct periodic maintenance 21. Reactive Maintenance Pros and Cons: reactive maintenance pros and cons, so the advantages are low. Initial cost. Andi can operate with lower fixed staffing requirements. Disadvantages increased cost you toe unscheduled downtime of equipment. Increased labor costs, especially over time, is needed. Dream repair or replacement cost involved with repair or replacement of equipment instead of comparatively low maintenance costs. Possible process interruption such as business interruption on need. A large inventory. Glad you can see there are many disadvantages associated with a reactive or breakdown maintenance program. Personally, I don't like this type off Nathan's program, unless is specifically a machine installed and ready to go. That can replace the one that's going to fail at some point in the future. But I think the biggest problem is simply that you never know how the machine is gonna fail and how that's gonna impact plan or the process. Simply. Too many variables are unaccounted for, and it's a bad maintenance strategy to use nowadays but is still in use and some plants to operate on a breakdown maintenance strategy. Although it's becoming less and less common 22. Preventive Maintenance: preventive maintenance. Preventive maintenance can be defined as follows Actions performed based upon a schedule actions performed should detect, preclude or mitigate degradation of a component or system with the aim of sustaining or extending its youthful work in life through controlling degradation to an acceptable level . So preventive maintenance is also known as scheduled maintenance on its essentially the strategy of maintaining a machine based upon a certain interval, such as time or mileage or kilometers or even service hours on. Then we're gonna maintain the parts of the machine. They're prone to failure in order that we can increase its useful work in life ideally, or at least theoretically indefinitely. The aviation industry pioneered preventive maintenance as a means to increase the reliability of aircraft where the consequences of failure are high. Examples of preventive maintenance tasks would include, but not limited to oil changes. Filter changes, clean of heat exchangers, replacement of pumps, seals, etcetera. By expending the necessary resources to conduct maintenance activities specified by the equipment designer, the equipment life could be extended on its reliability increased in addition to an increase in reliability. Financial savings also occur compared to using a reactive maintenance strategy studies indicated savings can amount to as much as 12 18% on average, depending on the facility's current maintenance practices. President equipment reliability and facility downtime. There is little doubt that many facilities, purely relying on reactive maintenance, could save much more mating percent by instituting a proper preventive maintenance program . While preventive maintenance is not the optimum maintenance program, he does have several advantages over that of a purely reactive program. By performing the preventive maintenance described by the equipment manufacturer, do useful work in life of the equipment could be extended on. This ultimately leads to financial savings. While catastrophic failures may not be prevented, the number of unscheduled failures with decrease compared to win using a reactive maintenance strategy minimizing failures translates into maintenance and capital cost savings. This is the primary reason for the widespread adoption of the preventive maintenance strategy in many commercial industrial plants. The largest disadvantage with the preventive maintenance strategy is that maintenance always occurs irrespective of if the machine requires maintenance or no. This creates unnecessary work whilst also increasing the chances of failure if the maintenance has not conducted correctly. For example, replacing aniline bearing with one that is misaligned and thus shortening the machines useful working life. So there's some important topics discussed here. Could see some common maintenance tasks, such as all changes filter changes change into bearings. Going the heat exchanger, etcetera, These air task typically associated with a diesel engine. You will be changed in oil filter. You will be changing the fuel filter. If you're diesel engine is attached, an alternator, then you're going to need to change the alternator bearings. Periodically. You're going to need to check the spray pattern on the fuel injector nozzles or on smaller engines. Just change the fuel injector nozzles. So there's a lot of different things that you're going to be doing in order to maintain that diesel engine in a constant state off readiness and also to ensure that its useful work in life can continue indefinitely, or at least theoretically indefinitely. Preventive maintenance or scheduled maintenance is the dominant type of maintenance that you will currently see. Use for diesel engines, as you can see originally came from the aviation industry, and that's simply because aircraft falling out of the sky because the machinery was not maintained properly is simply too big a failure with two larger consequences on as such, a breakdown or reactive maintenance strategy is not suitable. Notice also that when you're using a preventive maintenance strategy, you actually have a cost saving over time. So the cost of maintaining the diesel engine may be $5000 or 5000 euros per year. But the cost of purchasing a new diesel engine maybe $200,000 or 200,000 euros so that is a considerable amount of money on we can reduce the likelihood of happen to buy another engine so long as we invest a little bit of money per year in order to maintain the engine . So that's why you see nowadays a preventive maintenance strategy used for diesel engines on Nowadays. There's also been a slight shift towards predictive failure or predictive maintenance strategies, which we're gonna look at MAWR in the next couple of lessons 23. 24 Preventive Maintenance Pros and Cons: preventive maintenance pros and cons. Advantages. Cost effective in many capital intensive processes. Flexibility allows for the adjustment of maintenance period Odyssey. Increase equipment used for work in life. Reduced unscheduled equipment and process failure. An estimated 12 to 18% cost saving compared to reactive maintenance programs. This is the factor is going to be driving mawr arm or plants from a breakdown maintenance strategy. Do a shade jeweled or preventive maintenance strategy. The disadvantages are that labor intensive compared to reactive maintenance programs. Includes performance of unneeded maintenance on the potential for incidental damage to components in conducting unneeded maintenance. Unfortunately, the final point is true. If the machine is operating effectively on, there's no problem with it. Maintenance will usually be conducted anyway. If the maintenance is conducted in correctly, then we risk damaging the machine and well, short. And it's useful work in life. However, with proper training on the correct spare parts, you should be able to get around this problem. Let's now have a look. A predictive maintenance strategy 24. Predictive Maintenance: predictive maintenance. Predictive maintenance can be defined as follows measurements that detect the onset of system degradation, thereby allowing causal stresses to be eliminated or controlled prior to any significant deterioration in the equipments. Physical state measurement results indicate current and future functional capability. So if we put that into plain English, predictive maintenance is where you measure certain aspects off the machine. Look for tell tale signs that it may fail in the future. I think the simplest way to look at this is to instead think off your own human body. Now a lot of people, myself included, operate the human body on a breakdown maintenance strategy. In other words, they will go to the doctor when something's not working or when they feel ill. However, there are different maintenance strategies used for different parts of the body. For example, a lot of people will go to the dentist once every six or 12 months, so this is more a preventative maintenance strategy. A predictive maintenance strategy is where you go to the doctor and he'll take a blood sample. Measure your blood pressure, maybe take your temperature, neighbor stated urine sample on. If you have a different things on, he'll assess how healthy you are, Andi, if there's likely to be any problems in the future, so that is a predictive maintenance strategy. It's where you take annoy oil sample and send it away for analysis. It's where you measure the temperature of a machine and look for hot spots. It's where you look at the pressure within the combustion space on look to ensure the valves are closing at the correct time in order that you get your max pressure so that the engine is operating efficiently. That is predictive maintenance on this is a relatively new field that's come along a lot in the past 15 years. On it is reshaping the way we currently maintain machines, including the diesel engine. Predictive maintenance differs from preventive maintenance by conducting maintenance on the actual condition of the machine, rather than on some preset schedule. You will recall that preventive maintenance is time or interval based. Activities such as changing filters are based on intervals such as time intervals or operational hour intervals. For example, most people change the order near vehicles every 3000 to 5000 miles traveled. This is effectively basing the old change needs on equipment runtime. No concern is given to the actual condition on performance capability of the oil. He always changed irrespective of its condition. This methodology would be analogous to a preventive maintenance task. If, on the other hand, the operator of the car discounted the vehicle run time and had your analyzed to determine its actual condition and lubrication properties, he or she may be able to extend the all change until such time as your needs changing. This may be significantly more than 3000 to 5000 miles. This is the fundamental difference between predictive maintenance on preventive maintenance . Predictive maintenance is used to define needed maintenance tasks based upon the equipments condition. But preventive maintenance occurs irrespective off the equipments condition. So where is before? We may have a pump, and we would maintain the palm periodically at scheduled intervals, such as replacing the bearings. We won't do that with predictive maintenance, because what we'll actually do is we'll take some instrumentation on well, maybe measure the vibrations on the pump on. Then maybe we'll take a infrared camera on. We'll look at the temperature of the bearing on. Maybe we'll also have some ultrasonic measuring device that we can use to listen to the pump as its operating on using that device will also be able to detect problems such as if the Bering is gonna fail or no predictive maintenance equipment has the huge advantage that is non invasive. In other words, we can taken infrared camera and we just need to look at the motor in order to determine what the bearing temperature is. We don't need to open the motor. We don't need to shut down any part off the process. And this means that were less likely to damage the machine on sure on issues for working life. So that is a huge advantage compared to the traditional maintenance strategy employed, which is preventive or breakdown. The advantages off predictive maintenance and many a well orchestrated predictive maintenance program will significantly reduce unscheduled downtime on SAI. Inventory could be reduced significantly on spares could be purchased well in advance of scheduled maintenance tasks. Past studies have estimated that a properly functioning predictive maintenance program can provide a saving off 8 12% over a program utilizing preventive maintenance alone, depending on the facilities, reliance on reactive maintenance of material condition it could easily recognize savings opportunities exceeding 30 to 40%. In fact, independent surveys indicate the following. Industrial average savings resulting from initiation of a functional predicted Mazen's program. Return on investment 10 times reduction or maintenance costs. 25 to 30%. Elimination of breakdown. 70 75% reduction in downtime. 35 to 45% increase in production, 20 to 25%. Unfortunately, initially, starting a predictive maintenance program is no inexpensive training of implant personnel. To effectively utilize predictive maintenance technologies will require considerable funding. Program Development will also require an understanding of predictive maintenance on a firm commitment to make the program work by all facility organizations and management. The reason that I want to talk about predictive maintenance a little bit in this course is because it is slowly now coming into effect on diesel engines as well. Gone are the days we used to just ripped a diesel engine apart, strip it down, clean all the past, change the bits that are prone to failure and then put it back together again. You are less and less likely to see that the day today operations of machine involves changing filters on many other preventive tasks like that. However, with newer diesel engines, you'll still be doing those tasks. But nowadays you'll also have a computer that is connected to the engine. We'll have many sensors on the engine on these sensors will be talking to the computer on your diesel engine will most likely be continuously monitored as soon as it's put into service. So we're gonna be measuring things such as temperatures, pressures, levels, flow rates on. We're going to be sending all that data to the computer, and it's gonna analyze that, and it's gonna be looking for problems. Some diesel engines even send that data for the Internet to an offsite company on this company will analyze the data periodically and let you know if there's a problem or if there will be a problem in the future. From personal experience. Working on the large to strike engine, it was not uncommon that people 6000 miles away would find out we had a problem with our engine. Before we even knew about it. We would literally be sailing around in the Middle East or perhaps Malaysia somewhere like that on somebody from London would send us an email and say that fuel injector number three on cylinder number six is dripping on. We need to change that as soon as possible. So this gives you an idea of how technical things are becoming. And it's not limited to just people working on a ship. It for many, many people who use large diesel engines, some even for power generation. So it's a very new and interesting development, obviously, is also aspects where teams will come in and they will take condition monitoring equipment such as infrared cameras so that they can see the temperature across the entire machine on They'll take vibration analysis equipment or ultrasonic equipment, maybe even non destructive testing, and they will go all over the engine. And they were looking for problems. They'll be using these non invasive techniques to detect problems. So anyway, I just wanted to mention that during this course, because you may see things changing in the future. During my own engineering career, I've seen a shift now, from preventive to predictive maintenance on If you've got this background knowledge, you'll understand the reasons behind this shift, not just for diesel engines, but for pretty much every machine that's out there. So let's now get on with the next lesson. Never look at some of the advantages and disadvantages with predictive maintenance. 25. Predictive Maintenance Pros and Cons: predictive maintenance pros and cons. Advantages increase component. Operational life and availability. Allows for preemptive corrective actions. Decreasing equipment or process downtime. Reduce business interruption. Decreasing costs for parts and labor. Improved worker and environmental safety. Improved worker morale. Energy savings estimated 8 to 12%. Cost savings over preventive maintenance program. Disadvantages. Increased investment in diagnostic equipment. Increased investment in staff training and savings potential not readily seen by management . The savings potential is quite large, but unfortunately, most budgets are simply assessed over a 12 month period on they'll look for a return on investment or what their classes. A payback period. Unfortunately, a lot off predictive main and strategies do not have a defined payback period. It's very difficult to quantify and put into an excel she the cost that you are saving. And even if you do that, some people will most likely know. Acknowledge it. There is an initial investment in staff training on there is initial investment in diagnostic equipment, although what you'll see quite often nowadays is that some of this will be simply contract it out on. You'll have a company that does this every day of the week all year round and they will come in to your plan or they'll have a look at your machine, maybe your diesel engine, and they'll spend half a day going all over it and assessing its condition. If you're having the diesel engine maintained by manufacturer, what they were usually do is come with a laptop. They will plug the laptop into the engine control union, which is on the side of the engine, or mounted nearby, and they will extract all of the data from the engine when it's operating or how it's been operating in the past on They'll have special software then that can identify problems with the engine on. All of this is related to predictive maintenance, so it's very exciting and interesting field. And if you haven't seen much of it yet, I can guarantee you that you will in your engineering career. As time passes 26. Reliability Centred Maintenance: reliability centred maintenance. RCM Reliability Centred Maintenance magazine provides the following definition of RCM, a process used to determine the maintenance requirements of any physical asset. In its operating context. RCM methodology deals with some key issues not dealt with by other maintenance programs. It recognizes that all equipment in the facility is not of equal importance toe either the process or facility safety. It recognizes that equipment design operation differs and that different equipment will have a higher probability to undergo failures from different degradation mechanisms and others. It also approaches the structure of the maintenance program, recognizing their facility does not have unlimited financial on personnel. Resource is on at the use of both need to be prioritized and optimized in summary. RCM is a systematic approach to evaluate the facilities. Equipment of resource is then to match the to in order to obtain a high degree of facility reliability and cost effectiveness. RCN is highly relying on predictive maintenance, but also recognizes that maintenance activities on equipment that is inexpensive on or unimportant to facility reliability may be best to be left to a reactive maintenance approach. A top performing commercial industrial facility will often have several maintenance plans in operation well proportioned, similar to those given below less than 10% reactive will break down 25 to 35% preventive 45 to 55% predictive. Because RCM is so heavily weighted in utilization of predictive maintenance technologies, its program advantages and disadvantages mirror those of predictive maintenance. In addition to these advantages, RCM will allow facility to more closely match resources to needs while improving reliability. Decreasing Khost. So RCM is the king of all maintenance strategies were relying on predictive maintenance to assess a machines condition. But then we're relying on RCM to decide if that machine is even important in the first place. And if it's not, then we will most likely drop it from the maintenance strategy or maybe five potentially cheaper maintenance strategy, such as the preventive maintenance strategy. I would say that many plants that I visited during my time as an engineer we're heading towards this ratio, although normally preventive maintenance strategies would be here on predictive here. But the ultimate goal is to have a maintenance strategy. Looks very much like this 27. RCM Pros and Cons: RCN pros and cons. Advantages can be the most efficient maintenance program. Lower costs by eliminating unnecessary maintenance or overhauls. Minimize frequency of overalls. Reduced probability of sudden equipment failures able to focus maintenance activities on critical components. Increased component reliability. Andi incorporates root cause analysis. Root cause analysis is where you go back and look at failures. Identify the quarter of a failure and then take steps to mitigate that happening again. In other words, to reduce the probability of that happening again, or to eliminate the prospect of that happening again entirely. Disadvantages can have significant startup costs associated with training and equipment savings potential may not be readily seen by management. I would say these two factors are the two deciding factors on whether or not a reliability centred maintenance program is implemented or not. It takes a huge amount of effort from many different people on many different management levels to implement a reliability centred maintenance program. On If the budget ever gets cut for things such as predictive maintenance, you really do end up in a very tricky situation because the idea of maintaining the machines based on what you know about them predictive maintenance suddenly becomes a bit of an issue because you don't know so much because the budget has been cut. So the amount of information you have has been reduced. So you company make informed decisions anymore. But anyway, that's a very brief overview into different maintenance strategies. I did want to do that in this course because I thought it was quite relevant to the diesel engine. Now things are progressing over time, and hopefully from an engineering perspective, you've enjoyed getting a look at the different maintenance strategy types on. It will help you as you go through your career, because you'll notice these shifts from one methodology to another. On in the back of your mind, you'll be able to say, Huh? I understand why this is occurring now, so let's not go. Another look at a typical maintenance plan that would be associated with a diesel engine 28. Maintenance Strategy In Action: So here we have a typical maintenance plan associating with an engine. I can see that on a daily basis. We do things such as Check your level, check the primary fuel filter normally would be looking at the pressure differential across the filter in order to make sure it's clean. Check the cooling water level and then check the sea strainer. So this is an engine. It's actually called down by seawater. We used to see waters called the jacket water. There were other things after that. Such has changed the engine oil and filter. Check the V Belt tension adjuster valves and check the electrolytes level in the batteries , and that's after the 1st 50 hours of operation. Every 50 hours after that, check the V Belt tension and check the electrolyte level in the batteries again after the 1st 100 hours changed engine all in the filter every 250 hours thereafter. Change the engine all of filter. Check the air cleaner. Check the zinc electrodes on clean to see strainer zinc. So what they call sacrificial a nodes. You'll install those into any system that using seawater normally on. The reason is to see Warsaw will attack the zinc on. It will slowly Kuroda zinc away. But it's better than it does that because if you don't have the sacrificial and notes in place, the seawater will actually attack other parts of the system, such as the piping on the valves. So that's why you have sacrificial and roads in the sea water system in the first place. The air cleaner in this instance is simply air filter, so you can see that is general structure is to follow a shed George or preventive maintenance strategy on. We're gonna base that here on service hours, normally every 500 hours, check the Val clear and sees check primary fuel filter element and blah, blah, blah. So that's after every 500 service hours after every 2000 service hours or needed. Then we'll get to the bigger jobs that take a bit more time, such as checking and cleaning off the heat exchanger or inspecting of the starter motor and alternator. So these jobs have done less frequently, but they still need to be done in order that the engine could be run reliably. If we go over to the next page, we can actually see here that this table is taken directly from a maintenance manual. This will come from the manufacturer normally, and you'll see they'll give a list of tasks. Here they give a special I D code. And if we go down to the fuel system, we can see check primary Filter S P eight daily on. So we will do that task on a daily basis. If we look for the oil filter change lube oil filters on, if you go across that we done after the 1st 50 hours on, then it will be done every 250 hours thereafter. Notice, though, that sometimes if you're operating on items such as an emergency generator so we'll have a diesel engine driving a alternator, then this might not be suitable because on a yearly basis that emergency generator may only do 10 hours of work. So it will be a long time until we get to 250 hours off operation. If you look here, we can see a very small one in a very small five on. This actually relates to one performer maintenance once a year, even if our level has not been reached on five after the 1st 50 hours, so you'll see that they have accounted for the fact that if the engine is not in service very often, then we will simply go to number one, which says, Do it once a year. And this is all a preventive or scheduled maintenance strategy. You can see the level of waste, though, is gonna be quite high. We're changing the oil filter without even knowing it's condition. Maybe we don't even need to change it on. The fact of the matter is, if you've run the engine for four hours and then you change your oil filter once a year, it's highly likely that the oil filter is gonna be very clean, and it's still gonna be able to remain in operation. The reality is that point number one most people will ignore, or they'll remove the filter from the side of the engine. Do a quick inspection, make sure it looks OK, and then they will reattach the same filter to the engine again. Obviously, the manufacturer doesn't want you to do this. They would prefer it if you change the filter. All those like conflict of interest here, because if you do change the filter, you'll have to buy more spare parts from then on. Obviously, that's a very good business model for them. So there's definitely an element of common sense here that needs to come into play. But these maintenance strategy is there for a reason, and if you stick to them, then it's very likely you're gonna have an engine that has a very long, useful work in life. 29. Thermodynamic Cycles Introduction: So in this next section, we're gonna learn about thermodynamic cycles and gas cycles. Now there is why a lot of literature and theory associating with gassed cycles. You could literally doing entire course just on gas cycles. But what I want to do here, you just show you how we can take the knowledge from pressure volume on temperature on apply it to understand how a gas cycle works on. Hopefully, by the end of this section of the course, you'll be able to read a gas cycle. In the past, my engineering career. I used to look at these gas cycles and be slightly intimidated by them. That's because I never took the time to understand them. Once you take the time to understand them, they really are quite simple and quite useful. So let's get on now and have a look at them on. Hopefully, as a safe by the end of section will have a pretty phone grasp of what a gas cycle is and how you can read one 30. Pressure Temperature and Volume: So in the next few lessons, we're going to look at pressure, temperature and volume on. I'm gonna show you the relationship that all of those things have to each other. It's important to get a very rudimentary grasp off pressure, temperature and volume because it pops up a lot when you talk about diesel engines, especially when you start talking about PV diagrams and things like that where you are able to plot the pressure and the volume onto a graph, and then you can use this to assess if the engine is operating normally or no. 31. Amontons Law: So let's have a look now at Amazon's law, Amazon's Lorries, essentially a law that describes the relationship between pressure and temperature. The relationship to impression temperature is actually linear, and that means I should change the temperature. You're also going to change the pressure. However, this is a gas law so is relevant for gas is only the pressure of a given amount. Gas is directly proportional to its temperature on the Kelvin scale when the volume is held constant. Now Kelvin is just another means off temperature. Measurement on is actually minus 273 degrees Celsius. That equals zero Kelvin's. By the way, the important thing to remember here is that if you have a constant gas volume and you change the pressure, you will also change the temperature inversely. If you change the temperature, you will also change the pressure. The next known as Amazon's law 32. Charles Law: there is another law on this is known as Charles's Law on this law describes the relationship between volume and temperature. Now Charles is law states that the volume of a given amount gas is directly proportional to its temperature on the Kelvin scale when the pressure is held constant. So in other words, if we hold the pressure constant on, we adjust the temperature, then we're also going to adjust the volume. If we just a volume, then we're also going to adjust the temperature. But that's only we were holding the pressure constant. So is before we were actually holding the volume constant in Amazon's law, whereas now in Charles's law, were holding the pressure constant. But what you should realizes that pressure, temperature and volume they all have a relationship to each other on when we look at indicated cards in a moment on TV diagrams, you're going to see how important this relationship is 33. Pressure and Volume Diagram: We can also see on the diagram here that as the pressure increases, the volume is going to decrease on. As we dropped the pressure, we're gonna get a consequent increase in volume. Now. This makes sense because you think about it that piston moves down the cylinder. He moves down the combustion space. That combustion space gets larger as the piston moves further down towards bottom that center, so again increase in volume and we get a reduction in pressure if we look at it the other way around. If the piston travels towards stopped dead center, then we are going to get an increase in pressure on a reduction in volume because there's not as much space between the top off the cylinder liner on the top of the piston crown. So the relationship with pressure and volume can be expressed with this graph. 34. Diesel Gas Cycle: So we've talked briefly about pressure, volume and temperature on their relationships to each other. But let me now show you a pressure volume diagram. Now, this is actually a gas cycle diagram. It's called a diesel gas cycle. Diagram on it actually allows us to theoretically see what the engine is doing as it pushes the pistons up and down on how much work we put into the engine and how much we get out of the engine. This is an idealized diagram. Typically, they're not going to look like this, But we will have a look at a real world diagram in a moment. So let me walk you through. What's going on here? We've got pressure on the left side. This is our Y axes. We've got volume on the X axes. That is this arrow stretching off towards the right on the volume as it goes towards the right side of the screen, it's going to increase on the pressure as it goes towards top virus. Green is also going to increase what we have here from number one all the way up to number two is the compression stroke. Because, as you can see, the volume's decreasing, the pressure is increasing on. Then we get to number to between two and free. We get combustion now. Cue is a symbol for energy and it says the ACU in that's energy in we are adding energy on then from 3 to 4, you can see we've got the exhaust stroke on that. Is the system moving down towards bonded center? The volume increases on the pressure decreases. Concede though that where we say que in on cue Al, it's not possible realistically, to add or take away energy, energy can only change state. So we're changing the state of the fuel from the chemical bonds that it has to heat. And then we're gonna change the heat to kinetic energy, which we will see then, as movement off our engine parts. You cannot destroy or create energy. You can only transfer for one state to another, so please keep that in mind. It's a common misconception, but if you remember that, then you can always think yourself right. Where is the energy for this coming from? Where is it going to? And then once we get Teoh, number four will continue. There's gonna be some air that's substantive. Sexually exhaust gas goes out and see any GL on the process starts again. So compression Sorry. Compression for number one up to number two. Ignition combustion expansion. Power strike swap over some bowel sucking, Samir. On a way we go again. The work in can be measured over here on the workout over there. But the actual work done is when you take the energy input aan den U minus the energy output and you will have a net gain off work. 35. Thermodynamic Cycles: You might also hear the term thermodynamic cycle or gas cycle, and the diesel cycle is one of the most moan. Although the break in cycle is also quite well known, that's used for jet engines on the auto cycle, which is used for gasoline or petrol engines, so different cycles used for different engines. 36. Power Cards: Now what we're looking at now is a power card. Power cards are used to be able to see what's happening within the combustion space in the past. They would just screw a center into the top, off the combustion space or in the top of the cylinder head on. This would record the pressure within the combustion space on. You could measure that then on. You could then correlate that with the position off the crankshaft, which would let you know the position off the piston, For example, if it was a top dead centre or bottom dead center top, that center in our case would be roughly year on bottom. That center would be roughly here, but the same process occurs. You can see we've got an increase in pressure, a decrease in volume, and it's gonna go the way to the top on. We'll get combustion, then we'll get our power stroke. The volume will increase. The pressure will gradually decrease. After this initial peak on, it will go all the way back down again, and we'll start the cycle again. He's actually called a power card. Andi, if the engine is operating incorrectly, then we will see a diagram that is not like this. It's actually slightly different if the valves we're not closing correctly at the top here , and we would see some sort of squiggly lines because we're not reaching our being. Max. Maybe the fuel injectors were injecting too early, in which case this top peak over here might get pushed more over to the left on. We'll have a slightly weird loop that will stretch off more to the left and then back over to the right again on this is telling us that we're getting some form of pre combustion, so there's different bits of information we can ascertain from our power cards. You will see these types of cards used on larger engines and medium sized engines, but you will not see them used on smaller types of engines. 37. Compression Diagrams: Let's now have a look at a different type off diagram that also uses pressure volume on temperature to ascertain what's happening within the combustion space on the X axis or the lower axis, we are measuring time on on the Y axes, real measuring pressure. What's happening is the piston is coming towards top Dead centre were gradually increasing the pressure we get to this point here on. This is where we've achieved on maximum compression pressure. Well, then inject fuel and you can see we get our combustion on. We'll get an even higher pressure. At that point, we started power stroke and we go back down this way on. We end over here and we can repeat this cycle again. This type of diagram is called a compression diagram, and you can see that it's also possible if we don't have the combustion part off the compassion cycle that we can leave the vows closed on. We can close off the fuel supply, and if we do that, what will actually get is a line going back down here, and then we can use this graph to ascertain if the valves are seating correctly or that's one of the things we can use, the graph fall. If not, then we would notice that the pressure would not be smooth on both sides. When we're measuring the compression pressure on, we're coming up the side like this and then back down again. We will turn off the fuel to do this in order that we can get an accurate measurement. If we turn the fuel line and we get the combustion cycle and we end up with this peak here on, then it slips off gradually again there. This type of diagram will be used by manufacturers when they designed the engine. If your engineers medium sized or large, then you will also be able to use these types of diagrams. Typically nowadays, oh, people will arrive. We've a laptop and they'll be off to blood. The laptop in on there will be able to extract information from the engine, and they will get nice curves like this. And then we have to tell you if the injector is leaking or if you have piston rings that are passing or even if you're valves are not seating correctly. So quite useful diagrams that have, perhaps not what you see on a daily basis, but definitely good to know about 38. Gas Cycle Summary: so in summary. Just keep in mind that there are different thermodynamic cycles that exist, such as auto or diesel, they use for different types off engine. But in essence, the idea with the thermodynamic cycle is to describe the relationship between varying pressure on temperature and volume within the combustion space. By knowing that there's a relationship between pressure, volume and temperature, you can then use this knowledge to discover things like if valves a leak in the fuel injectors. A leak in if piston rings are passing or if you have blow by on all of this is very useful because it allows you to assess the engines condition without opening the engine up. So this is non invasive were not taken engine apart to inspect it. We're just using sensors on converting the knowledge that we gain from these sensors into something that we can use to assess the condition of the engine 39. Engine Protection Introduction: So now we'll talk about engine protection. Engine protection is very, very, very important. Engines costs generally quite a bit of money on one of the biggest problems. If your engine ever fails, is not going to be that the engine failed and it costs a lot money. One of the biggest problems is going to be all the knock on affects that costs potentially far more than the engine itself. Let's imagine for a moment we're using it. These ranging to operate a sprinkler pump. This is not uncommon because sprinkler pump should be normally completely isolated from the electoral system. Sometimes you'll have Sprinkle pumps that run by electric motors. Potentially, they will switch over to batteries during the loss of power. But the idea recently have been lost. Power was a fire. The diesel engine will come online on. People operate sprinkler. So let's imagine for a moment that the engine doesn't come online where it comes online and shuts down because of a situation such as low lubrication or pressure. This is obviously no ideal. You don't need the spring to pump very often, and when you do need it, the engine doesn't work, so you can see the importance here. Imagine the entire building burned down on. Do you have a loss off $100 million. Now, this is very bad. The engine yourself would not have cost $100 million. You've also got not just the loss off the building and the cost. But if it was a manufacturing plan, you will probably incur millions for a day also of lost revenue. So the implications are huge. Diesel generators are also used in, basically hospitals, many other public buildings. So imagine for a moment that the diesel engine did not start or it failed. Once it did start. All of a sudden, you're gonna have a public building without any power on again. This is not good. The reason you have the most generators because she needed in emergency the implications if you lose power in emergency might be quite large. And that's just for public buildings. For manufacturing plan, it may be even worse. A lot of the times the ventilation systems, for example, are up to you. Mostly generator. Imagine that they stopped working. Would this be a problem for the people working inside? Perhaps so you can see that the protection of the engine is very important. We want to protect the engine so that it can shut down in emergency needs to. But we also want to ensure that if it does shut down, there's good reasoning for it. On this next section, we're going first run fruit, the different methods we can use to protect the engine, such as level flow, temperature of pressure on. They're not going to show you some examples off alarms that 50 to a standard diesel engine . This section is quite important. You can apply the knowledge you get in this section two other engineering industries on I definitely recommend you do. 40. The Importance Of Engine Protection: so in this by the course, we're going to look at engine protection. We're going to look at how you protect the engine on and why. And I think one of most important things to realize in this part of the course is that the engine is a high value asset. That means it costs a lot of money. So I need to take steps in order that we can protect this asset or the engine in order to do this. But we're actually gonna do is install load of sensors on protection devices that will activate if our engine should be threatened by anything. When I say threatened, I mean things such as high temperature or low pressure or low level. So if we have in my oil level or a low or pressure or a high cooling water temperature, all of these things are there going to activate an alarm or shut down the engine. So let's now have a brief look at how we measure different aspects off the engine, such as temperature pressure flowing the levels in order to determine if the engine is operating within limits or not. 41. Level Measurements: so the first means that we're going to look out for protecting engine is simply by measuring the level off oil or water in the engine. So what? How is a form of measurement that allows us to other see the level or, if the level drops below a certain point, it will activate an alarm or maybe even a shutdown. So, for example, jacket water or cooling water system may have a header tank on this header tank will most likely have a gauge that allows us to see the cooler water level. Andi, you will also have a sensor which senses the level. Typically the type of sensor employer would just be a float on this float will go up and down like that. What we're seeing now, and if you should drop below a certain point, it will either open or closed circuit on. This will activate an alarm. We can also apply this to lubrication or system. We can measure the all level within your some or the oil pan on. If it drops below a certain level, then we will also get on along. So that is born means off protecting the engine by measuring the level 42. Temperature Measurements: another means off. Protecting the engine or another method is to measure the temperature. You might see a gauge like the one we're looking at now mounted on two different areas of the engine. On this allows us to look at things such as the cooling water temperature or perhaps the oil temperature on other things like that. So it's a good means off local visual indication nowadays, So you're not just gonna have local visual indication? You might use that as a reference when you're doing your rounds and checking different things on the engine. But when you actually have our sensors on, these sensors will detect the temperature, such as off the cooling water or off the lubrication or on. We'll send that information back to a computer. I will be able to see then the kuna, water temperature or the all temperature, the exhaust gas temperature etcetera on. We can see it on the screen, maybe weaken trend over time to see if there's any patterns. Maybe the oil temperature is increasing over time. Perhaps a cooler water temperature is increasing over time, but allows us simply to gather more information on with that information. We can make an informed decision, so temperature is definitely one off the main indicators used to assess if an engine is operating within the design limits. 43. Pressure Measurements: now here we have what they refer to as a board on pressure gauge or a pressure gauge on this is used to measure the pressure within a system. If the pressure increases and it will increase. Also on the gauge will see climb from, for example, 10 to 30. And if the pressure decreases then engaged, will also represent this by dropping down further on the left hand side, down towards a 10. As with the temperature gauge, though, this is purely a way to pass on the information to personnel such as you or myself as we do our rounds in order that we can see the pressure. Without this gauge, we wouldn't be able to see the pressure. We weren't able to see the temperature, for example either. So these gauges allow us to see the pressure that is all their doing. Their converting that pressure signal into something that we can visualize on, then make decisions about. For example, if this gaze jumped up now to 60 instead of 30 then I would wonder why that is on an engine is much the same. You may get pressure fluctuations like that which was seen now, but if it jumped all the way around to 60 or was off the gauge, then we start to ask ourselves what's happening. If this was an oil gauge and it dropped down to zero when the engine was running, then we should be very worried because we don't want a very Lowell pressure when engines running. Pressure itself is a very useful indicator for assessing and engines health. It's gonna be used for things like the jacket water cooling system. It's gonna be used for the lubrication oil system. If you're using seawater to call the jacket water, you're also gonna have pressure gauges installed there as well. Nowadays you're gonna have sensors, and these will feed back to the computer much like for the temperature gauges. And this means that we're gonna be able to constantly monitor the engine 24 7 365 days a year for every service our that's operating. So it's very, very useful. In the past, you would rely on people checking the gauges and confirming everything was okay. Not so much anymore. Now we just feed these pressure signals and temperatures signals to a computer on people will check those periodically But it is the actual computer itself on the software that monitors the engine and ensures everything is operating correctly, so pressure is a very important and useful indicator when monitoring a running engine. 44. Flow Measurements: on the final one that we're going to look at now is flow, so we're gonna measure the flow. You're not going to see this as often as you see other measurement indicators, such as measuring the level the temperature of the pressure, However, it is becoming more and more common. Flow sensors come in a variety of different shapes and sizes. Some are paddle wheels that look like three or four spoons that have been attached to a wheel on As the flow flows past the spoons. The spoons offer some resistance, so the flow causes boons to rotate around. A central point on that is a paddlewheel on depend on the number of irritations we can then detect what the actual flow rate is. Can also use ultra Sonics now to measure the flow rate or a propeller tight flow meter. But essentially the concept is the same. We're measuring the amount of flow that is going through a pipeline on def. We know what the flow is, Then we can say, OK, this is sufficient flow for a certain application. Are you going to see on a diesel engine? Well, it depends out big. The devel engine is on medium and large sized diesel engines. And yes, you are most likely to see some form of flow gauge, perhaps not on the oil or the cooling water system, but maybe on associating systems such as a sea water cooling system. The type off sensors we're gonna be talking about are going to be the level sensors temperature sensors on pressure sensors. So now you know different things that we can measure, such as temperature, pressure, flow on level. Let's go see how we can apply that to a diesel ranging in order to ensure that we are protecting our engine. 45. Overspeed Protection: So let's now apply what we've learned in the previous lessons to see how we can protect a diesel engine engine protection. That these legends designed with protection systems, to alert the operators off abnormal conditions and to prevent changing from destroying itself commonly referred to, is running to destruction overspeed protection because it diesel is not self speed. Limiting the failure in the governor injection system or sudden loss of load could cause the diesel too. Over speed on overspeed condition is extremely dangerous because engine failure is usually catastrophic on overspeed device. Usually some type of mechanical flyweight will act to shut off fuel to the engine on alarm at a certain preset rpm revolutions per minute. This is usually accomplished by isolating the governor from it's all supply, causing it to travel to the no fuel position. Or it can override the governor on directly. Trip the fuel rack to the know if your position where you have quite a small fuel injection pump for quite a small fuel pump, what you'll actually is a solenoid valve electromagnetic valve, and this will be used to actuate the fuel rack position in order that you can shut off the fuel to the pump, so that works quite well for smaller engines on larger engines. Medium sized engines, then, yes, you can also ice lately all supply to the governor, which then causes it to move to no fuel position. But either way, what you're trying to do is always isolate the fuel to the engine in order that the engine is starved of fuel on this ultimately will stop it, then rotating. In other words, it's going to interrupt the combustion cycle. And obviously, if there's no fuel going to the engine on there's no rotation, then we're not gonna have an overspeed event. If you want to know what an overspeed device is, imagine in your mind that you have a stone on the end of a piece of string and you swing in the stone around above your head. Now, if you swing this time very fast, Stone's gonna be thrown outwards radio early on, What's gonna happen is we're gonna pull this string tight the further we try and throw the stone outwards. So it was spinning around very fast above our heads. The stone is gonna be going around very fast, and he's gonna pull the string tight between the stone on your hand. However, if you slow down, then the stone is going to gradually reduce in height. So the tension in the string is not gonna be so tight. So instead of having a perfect horizontal line from our hand to the stone, what are actually gonna have these a slightly downward sloping line on this is because we're not rotating the stone as quickly, so it's not pulling the line is tight anymore. This concept is essentially the same as how an overspeed device works. If you rotate the changing very fast, what's actually gonna happen is a weight attached to the flywheel off the engine or close to it is gonna push a ball out. Sometimes on this board is gonna overcome the pressure in the spring, and it's going to make or break an electric circuit. Now when it does that, that sends a signal to the engine governor that the engine is running too fast and we've gotten over speed events. So that's normally. How it works is normally a spring on. There'll be a weight on Daz. This weight is rotating faster and faster by the engine is going to feel the need to go out further and further away from the center of rotation, and as it does so, it's gonna gradually overcome the spring force that's holding it in place. So we're gonna overcome the force in the spring on eventually, if it goes very, very fast, it's gonna compress the spring. And then we're going to send a signal to the government, and that's gonna shut down the engine because the overspeed device shuts down the engine. It's not unusual that you have two of these on if one actual rates, then you'll get an alarm and if both actuate then shut down the engine, but it really does depend on the size off the engine. I should also mention that whenever you have a very large machine with the high monetary value or whenever a machine is very critical to a process, you always or highly likely to have more than one sense of that you're relying on for stuff like shutdowns and alarms. Sensors can fail and they consent off false signals, and you don't want to shut down a huge boiler or a huge engine just because one sensor that cost $15 isn't working correctly. So what, they'll do their lives? Store more than one, sometimes up to three on, they'll rely on a voting system to see if the sensor is working correctly. Wanna say voting? I mean, if we have free sensors, then we'll call this A to out off three voting system to the sensors have to agree in order for something to be true. So if we have one sense of that, says a boiler is running too hot and the other to say, No, it isn't. Then we'll go with the majority vote and say, No isn't And then we'll try to repair that sense of its faulty as soon as possible. That's what The caller to our three Voting logic On an engine, you may have to sensors, and it might be that unless both senses of grief, then the engine won't shut down. Instead, you might get some sort of alarm, so keep in mind that you won't always have just one sensor that might be, too. That might even be three, especially for boilers on them or critical. The machinery item is, the more senses you're likely to have installed in, the more complicated the protection becomes around that machine, 46. High Jacket Water Temperature: have a look at the jacket water system or the water jacket. Water doctor Water cooled engines can overheat if the cooling water system fails to remove waste Heat. Removal of the waste heat prevents the engine from seizing due to excessive expansion of the components under a high temperature condition. The cooler water Jackie is commonly where the sensor for the cooler water system is located . The water jacket temperature sensors provide early warning of abnormal engine temperature, usually an alarm function. Only the set point is set such that if the condition is corrected in a timely manner, significant engine damage will be avoided. But continued engine operation at the alarm temperature or higher temperatures will lead to engine damage. So here we have a high temperature alarm for the jacket water system or the cooling water system. Typically, this is only going to be one sensor, and usually the sensor will connect to the monitor. In equipment on, you should be able to see what the temperature is, for example, 80 degrees a degree Celsius on. Then you use software to calculate a high temperature along, and then a high high temperature alarm. It might be the one high temperature is theological on one high high temperature is the shutdown. This principle off low, low, low and high, high high is normally used for out the engineering industry, and it gives you a quick reference to how hot or how cold, or how low a temperature or level is etcetera. It's important to keep a close eye on the jacket water temperature, because if it starts to get very high, then you will have to shut down the engine or slow it down significantly in order to avoid any damage to the engine. If the engine does sees, then you haven't got much else to do over them. Wait for it to cool down on hope that actually restarts again. If the jacket water temperature starts to get above 100 degrees Celsius, then it's going to start flashing off to steam. The jacket were system is gonna be on the pressure maybe three or 3.5 bar, and if you increase the pressure, then the evaporation temperature off the water also increases. Or what I should say is the boiling point of the water increases. So if we've got a system that tend bar pressure, then the water is not going to evaporate at 100 degrees Celsius or probably know even a 110 degrees Celsius. If we take out presser downtown atmospheric pressure, then the water will evaporate at 100 degrees Celsius on. If we take a pressure down to a vacuum, then the water's gonna evaporate at a much lower temperature, maybe even 60 or 70 degrees Celsius. But most engines have a pressure off three or 3.5 bar and their cooling water system. And that means if you start to get above 100 degrees Celsius or going towards 110 degrees Celsius, then you're gonna get some of that water flashing off on. Then you will get a problem because you're gonna get pockets of vapor throughout the engine . On this means the areas that should be called down by the cooler water and no longer called down as much because the vapor does not absorb as much he as water does. And then you're going to get localized overheating. Not only that, but if the pump is centrifugal, which is unlikely, but it may be, then it's not gonna be able to pump the vapor. The pump is entirely be gas bound, and that means you're not going to get any cooler awards circulating through your engine whatsoever. So it's quite serious if you have an over temperature condition. But generally, if you keep in Iowa around the engine for leakage off, cooling water from the Cold War system, usually the cooler water or have a red dye in it or a blue dye that makes it really easy to see if it's leaking on, providing you not get in loads and loads of cool water forming a pod. London If the engine you should be OK, because the loss of cooling water is a reason for overheating of the engine, your often gonna have level alarms fitted to the cooling water head a tank. This means that if cooler water drains from the cooling water tank will get a low level along and then you get a chance to top up the cooling water system in order to avoid an overheat situation or a leech goatee. Engine inspector on, Look for leakage and try and ascertain where that cooling water is gone. Slow leakages over time and normal. But if you're topping up the cooling water system every couple of days, and you definitely do have a leak somewhere in the system on. You'll need to find that as soon as possible. 47. Exhaust Gas Temperature: exhaust temperatures in a diesel engine. Exhaust temperatures are very important and provide a vast amount of information regarding the operation of the engine. Hi exhaust temperature can indicate an overloading of the engine or possible poor performance due to inadequate scavenging. The cooling effect in the engine extended operation with high exhaust temperatures can result in damage to the exhaust valves piston on cylinders. The exhaust temperature usually provides only an alarm function, so this is true. The exhaust temperature is usually an alarm function. There's nothing more annoying than having an exhaust temperature alarm that keeps randomly going off every 10 or 15 minutes. The reason it's annoying is because when you reset the alarm, it'll golf again 10 minutes later when you're not expecting it. And then eventually what will usually happen is people will tag the alarm, which means they'll disable it on. Then it won't go off every 10 minutes. If they don't do that, what they'll do is raise the exhaust temperature alarm limit so it's 20 degrees higher than previously. Waas on this will stop the along going off. Unfortunately, this hasn't really solved the issue. Whatever was causing the high temperature alarm in the first place has not been found. All we've done really is raised the exhaust temperature alarm set point in order that the alarm doesn't go off. So in other words, it's more or less a useless along. However, this practice is no unusual. I've actually personally done it a couple of times. It was a big issue. Sometimes on a boat. We have liquid flowing from one side of the boat to the other, and that often meant when the boat was rolling very slowly from the starboard side on the right to the port side. On the left, the liquid was role so slowly that it would set off all our high level alarms. And then, once it had set them all off, it would roll back the other way and settle for the high level alarms in the tanks on the opposite side of the ship. So you can imagine this was very frustrating. Even with the delay of 30 seconds until the alarm went off, we were still saying off the alarms and alarms for exhaust temperatures are much the same, although slightly more constant if you get serious issues with exhaust temperatures on the exhaust gas manifold, you'll start to notice that the paint on the exhaust gas manifold will lose its color. It will start to go brown as it gets heated up on. In very severe cases, the paint will actually start to blister on. It will literally flake off the metal. But that's obviously not good. And it's a sure sign that whatever is happening in the exhaust gas manifold, it must be very, very hot. I've also seen it that the exhaust gas manifold runs so hot that the metal starts to change color and takes on a bluey ready tinge on. If the metal starts to take on a blue tinge, then you really have heated up that manifold to its limit. We were actually using a wet exhaust gas Manafort. So we were spraying seawater into the exhaust gas manifold in order to keep it cool and to separate the dust particles from the exhausts before it was ejected from the ship. But unfortunately, the valve that allowed to see water to go to the exhaust was actually closed, so there was no cooling happening in the exhaust manifold whatsoever on the metal got very , very hot. The paint blistered on war less fell off the exhaust gas lagging, which is used to insulate the piping cooked to such a degree that it started to give off a very weird smell and became very, very hard, even though usually it's quite soft, and it was actually the smell that alerted us to the problem. Other problems followed after that, such as the valves that were further down the line in the exhaust gas system. They all got cooked and expanded lot, and they couldn't be closed anymore. The seals around the valve hadel cooked as well, and that meant that became incredibly hard because so made of a night troll rubber type of material so they would no longer seal correctly on became very, very brittle. So all of this occur because we had very high exhaust gas temperatures. 48. Low Lubrication Oil Pressure: lo lube Oil pressure, low oil pressure or loss of oil pressure, surrender and engine totally inoperable within a very short space of time. Therefore, most medium to larger engines will stop upon low or loss of oil pressure. Loss of oil pressure can result in the engine seizing due to lack of lubrication. Engines with mechanical hydraulic governors will also stop due to lack of oil to the governor. Low oil pressure scenario will usually shut down the engine. The oil pressure sensors on larger engines usually have to low pressure set points. One set point provides early warning of abnormal or pressure on alarm function. Only the second set point can be set to shut down the engine before permanent damage is done. Lo Lukoil pressure alarms and set points etcetera are, in my opinion, the most important alarms on the engine. If you get a Lowell pressure or no oil pressure, then you're really in trouble. You have a very limited amount of time before the engine seizes. As soon as the oil pressure drops, all of those metal components of our operating literally hundreds of different components, all operating and working in unison together, a gonna suddenly start to rub on each other as they rub on each other, you're gonna get friction on. As you get more and more friction, you're going to get elevated temperatures. After that, you're gonna get micro welding on. Eventually you're going to get seizure, and this happens in a very short space of time. So I remember that the oil is not just lubricating. It's also removing the heat. So without the oil, you're neither lubricating nor removing the heat on. This is going to give you a big problem. It's because the problem is so large, with a low oil pressure or very low or pressure that it has an alarm and a trip function. We come back here to our lower pressure and low oil pressure set points. That's why the engine will be set up with a lower pressure set point on a low, low oil pressure set point. And that will be an alarm on, then a shot down. So it's a very important alarm, and things that might cause this alarm to trip would be things such as a very dirty oil filter or several dirty or filters on. For this reason, normally on the side of the engine. There'll be an option to change over from one oil filter to another, so you'll be changing over from an in service oil filter toe, one that's not in service. And hopefully the one that's not in service is a new clean oil filter that's primed and ready to go. I have never person seen the oil pressure rapidly drop off last, and engineers and operation. I think the only time this is going to occur is if you have a severe oil leak on. The oil is literally running out the side of the engine. Maybe the oil pan under the engine is cracked and the all is leaking directly out of the sump. And if this happens, then year, you're going to be in a lot of trouble very quickly, cause he always gonna leak through the oil pan and you're gonna have no will left in your son, and that's gonna happen very quickly. But other than that, I can't imagine how this would occur. Suddenly, I think generally it's a problem that you can identify over time, such as 30 oil filter or maybe all that's being burned off in the combustion space over time, and you've got more than enough time to dip the engine, check the oil level, check the filters and ensure that everything is operating correctly. In addition to that, it's important to realize that the sensor that is measuring the lower pressure on possibly another sensor that is also measuring the oil pressure. Both of these sensors need to be tested and calibrated. Sometimes they'll be fitted on a small man, a fall to the side of the main lubrication oil pipeline. And if that's the case, then you might want to remove the sensor and just check that this small pipe is clear and not clogged up. Sometimes this small pipe that connects the manifold might get blocked. And if it does, then your sense is not gonna work correctly, just going to record the last pressure that it had. And as the pressure in the engine or system changes, there's gonna be a delay between when the sense of recognizes that, or maybe the sense of where, recognize that will measure it whatsoever. 49. High Crankcase Pressure: my crankcase pressure. Hi. Crankcase pressure is usually caused by excessive blow by gas pressure in the cylinder, blowing by the piston rings in into the crankcase. The high pressure condition indicates the engine is in poor condition. The high crankcase pressure is usually used only as an alarm function. I just read the tip quickly before we talk about the high crankcase pressure, because then the lesson is complete. The terms Ellen Hey, change. Refer to low, low and high high alarms of trips. For example, educational system for an engine may have a Lowell pressure alarm on a low, low oil pressure shut down. So we talked about that earlier in the lesson. So let's return to high crankcase pressure. Higher crankcase pressure for smaller, medium sized these engines is not such a big deal. In some respects, you'll recognize that you have a positive pressure in the crankcase, and you'll notice that you'll need to replace some piston rings in order that the exhaust gases in the combustion space don't blow by the piston rings and into the crankcase. Normally, if you change the piston rings, this problem will go away on small and medium sized diesel engines. You'll also normally have a crankcase breather. Filter on this breather filter allows you to separate the oil vapor from the air within the crankcase on the, or vapor will usually be returned back to your sump on the air, where you should be fed into the turbocharger. So that's a crankcase breather filter. Often these be manufactured by someone such as John Deere or Parker Hannifin. I believe he's also manufacturer. They're called recall Filters on these types of filters are relatively new in comparison to the older types, such as fuel filters and oil filters, etcetera on larger marine diesel engines, Crankcase pressure is a big deal. The reason that crankcase pressure is a big deal is because in the past they had crankcase explosions. The crime cases on large diesel engines are so big that you can literally walk around inside them. They're incredibly sleepy because everything's coated in oil. So when you get inside, your climb through one of the doors opens up beneath one of the pistons and you can go into the crankcase and you built to walk around, always holding onto something. Zittel ladders inside the crankcase and you'll hold onto something say Don't sleep over or fall over too much Andi. Below the main crank webs, there'll be a lot of oil that's not the main or something. But it just accumulates there anyway, sort of probably several tons of lubrication all on. Then you have all the all coaching, all of the parts as well. So what happened in the past within this crankcase is we would have a bearing, and this might be a crankshaft bearing or a bottom, and bearing on it would become incredibly hot due to poor lubrication as it became hot cause UAL to flash off and it would become a oil mist vapor. Now, this oil, Miss Vapor would then create an all miss cloud above the bearing, or it would accumulate within the crankcase on eventually would become so large that this oil mist cloud would touch upon the hot bearing on the whole bearing would heat up more or less again on it would cause it to combust on what followed after that would be a huge explosion. It would blow off all of the crankcase doors on. Then, after that, it would suck low to very into the crankcase. On another explosion would follow afterwards. So that's what I call the crankcase explosion. It is definitely something that you don't ever want to see in your lifetime, and you definitely don't want to be an injury and when it happens. But in the past, people have died because of these crankcase explosions, so measuring of crankcase pressure is important in this respect. Although what they actually do to protect against crankcase explosions is they sample the air within the crankcase on. If there is a high level of oil mist within the crankcase, then you will get an alarm and if it continues to rise and you can shut down the engine before you run the risk of a crankcase explosion. 50. Engine Protection Final Thoughts: So I hope that gives you a brief overview of some of the protection devices that you are likely to see on a diesel engine levels. Temperatures, pressures, flow rates. Not so much, but sometimes all of these air gonna be used to protect an engine. If you remember everything you've learned in the past few lessons concerning protection a guarantee that you can apply it to pretty much every engineering industry wherever you may be working. The concept of measuring flow rates on temperatures, on pressures on levels and even using things such a centrifugal force or centripetal force to actually overspeed trips, etcetera all of those concepts, but just copied and pasted all over the engineering world. If you look in the electrical transformer, one of the big ones that using power stations, they use a lot off level trips. If the oil level within the transformer gets too low, a little trip and shut down the transformer. If you look at a very large boiler such as that for a power station, they will always use a two out of three voting logic, and they will use that to measure stuff such as the water level within the boiler. If the water level gets too low, that is going to cause a catastrophic failure. And so something that is measured by three independent sensors on they use a vote in logically in to assess if one of the senses is faulty or if the boiler really does have a low level. So the logic is just copy and paste it into many different industries. And I hope now you understand how that all works and how you can apply it to different machines, or at least perhaps analyzing machine in your own head and think about how you would protect it. What devices you would install on how you could get all those devices to work together to ensure your machine is adequately protected. Let's have a quick summary in the next lesson. 51. Engine Protection Summary: most meat to large size diesel engines have as a minimum the following protective alarms and trips. Engine overspeed alarm trip, high water jacket temperature along high exhaust temperature along low lube or pressure alarm and trip my crankcase pressure along. So those are the alarms and trips that you're most likely to see on a diesel engine or as a minimum. Other things that you may see are things such as battery voltage low. That's going to be very important because you need a healthy battery in order to start the engine. Charging current low for the batteries. Also, very important fuel pressure alarms. You may also have those differential pressure alarms measuring across your filters and fuel filters, etcetera. You'll be able to see the differential pressure across the oil filters and the fuel filters on if it becomes too large. It's a good sign then, that you'll need to change the filters that may also be connected to the main alarm system . A differential pressure indicator will usually also be fitted onto the air filters. Sometimes we'll actually happen is they'll be a small type of float in a way on as the differential pressure becomes quite large, this float is gonna be sucked downwards or pressed upwards. Andi that's going to reveal a red bile on this gives you an indication that the air filter needs to be changed. Other signs of the air filter's dirty would also include the exhaust gas temperatures becoming elevated because you're not getting the air in there during the scavenging period to cool the combustion space down. So it's also a good indicator. I know at the moment, for very large diesel engines they're installing in excess off. 3000 different sensors on all of these sensors work together to protect the engine and to feed data to a computer on a medium sized or small size diesel engine. You're more likely to have less than 10 main sensors on most of those we've already talked about. Level sensors are very useful. You'll be able to use them for oil tanks or for oil. Some. You'll also be able to use them for an external fuel tank, for example, and in for the jacket water cooling system to measure the water level there as well. They're normally very reliable, very easy to test on there, just another cheap way to protect the engine, but could also save you a lot of money in the future. So that's a brief overview off engine protection. Have you found that useful and interesting? In the next section, we're going to look at the engine starting circuit. 52. Starter Circuit Introduction: this section of the course is quite sure we're going to look at the start and circuits associating with these legends, particularly electrical circuits and compressed air, etcetera on. Also gonna look at some other little things that were installed onto the engine that allow us to start it when the engineers, for example, very, very cold on this cool glow plucks. So getting to this section now, it's quite a simple and straightforward section on. After that, we'll look at some governors. 53. Starting Circuits: starting circuits. These legends have as many different types of starting circuits as there are types, sizes and manufacturers of diesel engines. Commonly, it could be started by air motors, electric motors, hydraulic motors on manually. To start circuit can be a simple manual start, push button or a complex auto start circuit. But in almost all cases, the following events must occur for the starting engine. To start. One to start signal is sent to the starting motor. The air electrical hydraulic motor will engage the engine's flywheel to starting motor. Will crank turned the engine. The starting motor will spin the engine out high enough rpm to allow the engines compression to ignite the fuel and start the engine running free. The engine will then accelerate toe idle speed. When the starter motor is over, driven by the running motor, it will disengage from the flywheel. So, essentially, how we start an engine. We send a signal to the starter. It engages with the fire wheel. It rotates. The fly will. Which road takes the engine on? Then the engine will start. It will goto idling. Speed starter motor will disengage on. Then we have an operating engine And that's the starting sequence off the engine finished very important that the starter motor does disengage. If you have any problem with the solenoid valve or anything like that, actually engages the starter motor with the flywheel, then there's a chance to start. A motor might stick if it sticks for more than, say, 30 seconds, and the starter motor most likely is going to be damaged Beyond repair. The teeth off the starter motor often get eaten up by the main flywheel or the motor will burn out. Having a spare starting motor available along with the associated gearing for the beauty Etcetera is always good practice and definitely recommended on very large engines. You won't actually use a starter motor in this respect. What you're actually going to use is compressed there on your use, compressed there to literally push a huge piston down, which is gonna weigh several tons on. You'll push all of the pistons down in sequence until you achieve a good momentum were good speed on. Then you will inject fuel on the engine will be able to run on its own. If you didn't use compressed air, it would be very difficult to use a starter motor that is large enough to rotate an engine that weighs several 100 tons, and that's why compressed there is used and you'll need a lot of it. 54. Glow Plugs: Because of these, Laingen relies on compression heat to ignite the fuel. The cold engine can rob enough heat from the gases that the compressed air falls below the ignition temperature of the fuel. To help overcome this condition, Some engines, usually small to medium sized engines, have glow plugs. Glow plugs are located in the cylinder, head of the combustion chamber and use electricity to he. An electrode at the top of the globe bug, he added, by the glow plug is sufficient to help ignite fuel in the cold engine. Once the engine is running, the glow plugs are turned off in the heat of combustion is sufficient to heat the block and keep the engine running. Larger engines usually heat the block. Onda will have powerful starting motors that are able to spin the engine long enough to allow the compression heat to fire the engine. Some large engine Jews air start manifolds to inject compressed air into the cylinders, which rotates the engine during the start sequence. So compressed air large marine engines are going to use this starting method and even some quite large medium sized engines. If an engine is very cold, then you're going to need glow plugs to heat the cylinder heads up on this. That makes it easier for the fuel to combust. You might have a high pressure ratio, but essentially it's the high temperature develop when you compress the gases within the combustion space, which causes them to ignite. If you can't get this high temperature than the fuel, simply will not ignite. And in order to get around this problem when you're starting a cold engine, you have glow plugs and their heat up in order that you can get the desired temperature you need for combustion. Once the engine is running and generating its own, he then you won't need to close plugs anymore. The glow plugs themselves are essentially just resistors will draw electrical current from a battery. Normally, on this electrical current passes for a resistor on generates heat, and that's what heats up, sealing the head off the engine 55. Engine Control and Governors Introduction: in this section, we're going to look at centrifugal governors on also electrical hydraulic governors ongoing explain to exactly how they work on. We'll use some images. There is a bit of carry over here for the previous diesel engines course, so if you know a centrifuge government works already, you can skip that section. However, the electrical hydraulic governors and the general means that we used to control the engine speed are discussed in this section on if possible, it's best to work through every lesson. 56. Engine Control: engine control. The control of the diesel engine is accomplished through several components that camp chef , the fuel injector on the governor. The camshaft provides the timing needed to properly inject the fuel. The fewer injector provides a component that meters and injects the fuel on. The governor regulates the amount of fuel that the injector is to inject together, these three major components ensure that the engine runs at the desired speed. My next few lessons. What it's gonna do is have a look at each of these components were not gonna have a look at the camp chef because that was covered in a different course. We will have a brief read about the fuel injector. The lesson associate with fuel injector is quite long, but I'm actually gonna trim it down and just try and explain the most important aspects as quickly as possible on we'll have a look. A governor will have a look at the traditional type on. Then we'll have a look at the type they slightly more modern 57. Fuel Injectors: fuel injectors. Each cylinder has a fuel injector designed to meet her and inject fuel into the cylinder at the proper instant to accomplish dysfunction. The injectors are actuated by the engines camshaft. The can chef provides the timing and pumping action used by the injector to inject the fuel . The injectors me to the amount of fuel injected into the cylinder on each stroke. The amount of fuel to be injected by each injector is set by a mechanical linkage called the fuel rack, or by using a solid noise valve. Common rail engines, if you're at position, is controlled by the engines governor. The government determines the amount of fuel required to maintain the desired engine speed and adjust the amount to be injected by adjusting the position off the fuel rack. So we have a can shaft, which controls when the injector opens and closes. Or we will have a solenoid valve, which controls the opening and closing off the fuel injector. If we using a solenoid valve which is in the electromagnetic valve, then we will send an electrical signal to the solenoid valve, which is normally mounted on top of the injector. Can actually see it. This section here on the electrical connection will connect there. Electrical signal will come in on the solar noise receives this electrical signal. He creates an electromagnetic field which pulls up a piece of metal, which is then going to open a valve or opener fuel injector. So we're overcoming the spring pressure within the fuel injector in order to inject the fuel. And that's how a common rail diesel engine works. Or a common rail fuel injector with the mechanical type will simply use the camshaft. And the camshaft will push up a push rod or similar on this war, then pushed down on a part of the fuel injector which will open the fuel injector on when the camps after rotates past this point, then the push rod will be released again. It will lower down, which takes the pressure off the fuel injector spring on the fuel injector spring, then closes three injector again. So that's how the mechanical version works. I'm not gonna go into much more detail about fuel injectors right now, because essentially, they're just vows that are opened mechanically or by using a solenoid valve, which is electronic common rail diesel engines are more and more common now days because they are more efficient than there, purely mechanical counterparts. Let's kind of look now at the governor. 58. Governors: governor. But these legends speed is controlled solely by the amount fuel injected into the engine by the injectors because of these legs and is not self speed limiting it requires not only a means of changing engine speed or throttle control, but also means of maintaining the desired speed. The government provides the ancient with feedback mechanism to change speed as needed and to maintain a speed. Once reached, the governor is essentially a speed sensitive device designed to maintain a constant engine speed regardless of load variation. Since all governors used on diesel engines control engine speed through the regulation of the quantity of fuel delivered to the cylinders, these governors may be classified a speed regulating governors. As with the engines themselves, there are many types of variations of governors in this course. The common mechanical hydraulic type governor will be reviewed on the older style mechanical centrifugal governor. The major function off the governor is determined by the application of the engine. In an engine, it's required to come up and running only a single speed. Regardless of load. The governor is called a constant speed type governor. If the engine is manually controlled or controlled by an outside device with engines be being controlled over a range. The governor is called a variable speed up governor. If the engine governor is designed to keep the engine speed above a minimum on below maximum, then the governor is a speed limiting type. The last category of governor is a load limiting type. This type of governor limits fuel to ensure that the engine is not loaded above a specified limit. I know that many governors act to perform several of these functions simultaneously. Example. One A. C. Electrical generators use constant speed engines to maintain a specific frequency. For example, 50 Hertz example to a diesel engine in an automobile operates over a variable specified range in order to change your mobile speed. So different types off Governor here. This one year is used for electrical power generation. Generators fired by diesel engine are gonna operate a specified speed, so we're gonna have a constant speed type governor. The idea is to match the speed to the hurts. Typically, a 50 Hertz generator will operate a 1500 rpm. Another common speed is 1800 rpm, but it depends how many poles the generator has a number of polls within the generator or the alternator dictates the speed required in order to obtain the hurts desired. Can see underneath that a typical diesel engine automobile would be a variable speed type governor, because we're gonna manually change the speed of the engine by, for example, putting our foot down on the accelerator pedal. So there are different types of Governor. The old type of governor that you will likely see in a museum is a centrifugal governor. Very simple concept, but still very interesting, Andi, one that we're gonna look at in this course in more detail. In fact, we look at both types, but this one in more detail is a mechanical hydraulic type governor on this same or modern type of governor. For those who did the original diesel engines course, then you will already know something about centrifugal governors. So the short lesson conservers a bit of a refresher, or you can skip it if you really want to 59. Operation Of A Governor: operation of the governor. The following is an explanation of the operation of a constant speed hydraulically compensated governor using the Woodward brand governor as an example, Principles involved a common in any mechanical and hydraulic governor. The wood would speak of no operates a diesel engine fuel racks to ensure a constant engine speed is maintained Any load the governor is a mechanical hydraulic type. Governor on receives its supply of oil from the engine lubricating system. This means that a loss of Lubell pressure will cut off the supply of all to the governor and caused The government has shut down the engine. This provides engine with a built in shutdown device to protect the engine in the event of loss of lubricating or pressure. So we're actually going back to the type of protection used for the engine. And we can see here that the governor actually has a protection system in built into it. And if the engine duplication or pressure drops and the governor will move to a position that isolates the fuel to the engine on, then the angel stop on in this way we can ensure that we're not operating the engine when there is no lubrication or pressure or very low lubrication or pressure, would would is actually a manufacturer off. Governors there used a lot with these Lane Jing's. You'll see them a lot if you're working on small and medium sized diesel engines. Would put its entire business model is built around the fact that they produce governors and control units for governors on ways to synchronize generators with a power network, etcetera. So they're heavily involved in the electronics industry. And if you do work on a diesel engine, it's highly likely that you're going to see something manufactured from Woodward. 60. Simplified Operation Of A Governor: in this lesson, we're going to look a simplified operation of a governor on. We'll look a strictly mechanical governor on. Then we will look a hydraulic, mechanical governor simplified operation of the governor, mechanical governor at the start of the Industrial Revolution, It soon became parent that some form of automatic controllers required in order to operate steam engines constantly and reliably. The first humans were used to control steam engines and their associated output. But this often lead to human error with catastrophic consequences. For example, engines over speeding will result in failure. Victorian engineers soon developed a simple device which could be used to regulate the speed of steam aging consistently and reliably, the device became known as the centrifugal governor. We conceive it more of us in few, Governor, in this video or after this lesson. But essentially as a speed increases or as the engine speed increases, these fly balls are gonna get thrown outwards to decide due to centrifugal force. Andi, they're gonna pull up this plunger, but is lever on that is going to slow down the engine on. As the engines be decreases, the fly ball is gonna fall back down again. towards the centre rod on this, Gonna increase the fuel on the engines, going to speed up on the fly ball is going to be thrown out mawr horizontally again and it continues like that. So that's how they used to control the speed off an engine, sent fewer governors and no longer used today. But the concept could still be used and applied to control the fuel supply to an engine and consequently control the engine speed click on the image below CIA working animated model with the associative video. So if you wanted to review click here on, we would be able to access interactive three D model We can actually see. The governor here has moved its fly balls out to the side, which means the engine is now running quite fast. We can see it pull the plunger upwards, and as the engine slows down again, the fly ball is going to come in words and the plunge of will drop back down again 61. How Centrifugal Governors Work: today, we're gonna look a centrifugal governor on. I'm going to talk you through some of the components, explain how it works and what it was actually used for. Now, the word governor actually means boss in English for chief on. The reason has that name is because it was used for control applications and it would control, for example, the speed often engine, that the term governor is still used today. Although obviously things have moved on the last 150 years on, we don't really have mechanical governors. Or especially not like this. We have more Elektronik governors, although there are some mechanical governors available, but it's not as common as it used to be. So it's diving now and have a look at some of the components we can see below the governor . We have a bevel gear arrangement. That's these two gears here. One is vertical wanted horizontal as a bevel gear. We can see the drive shaft coming in along these horizontal actually hear through the wall on the drive Chef will be coming from, for example, and engine on it will be fed from some sort of gear or pulley arrangement, so as it comes through, it's going to drive the gear on the top, the one that's horizontally orientated that's going to spin on. Then we're gonna come up here to ah, centrifugal Governor Centerview. Governor is the whole piece of apparatus that we're looking at now at the middle or in the middle with actually spindle on the lower section. We have a sleeve for sliding sleeve on the outside, the two round object you looking at. These are waits. Refer to his fly balls, and then we got to linkages and to arms. Now what's gonna happen is as the centrifugal governor accelerate. So as the whole thing spins, you're going to see the sleeve. The low piece moving up and down on as it moves up and down, is going to move this link each. This whole arrangement here on that is going to then open, or at least change the position off this valve in there. So I've talked you through how it works, but I probably should have just showed you would be a lot easier. So let's check it out. So now it's spinning and it's been quite slowly now it's increased in speed, so the spindle has moved up slightly, reaches back that up again. I can show you again, spinning slowly, increasing speed to fly balls move out. And now they're at their for this position. Notice that the fly balls now are extended further out from the sleeve. Then they were originally So what's happening is an engine, for example, will be rotating at a certain speed. Let's say 100 rpm and it's gonna rotate the horizontal shaft at 100 rpm, assuming that the horizontal shaft is geared directly. So we got 100 rpm on the horizontal shaft on. We're going to transfer 100 rpm through the bevel gear here and to the centrifugal governor . If we back up now, we can have a look at 100 rpm. Should start off. There would be, Oh, so you know it's the arms are no particularly far away from sliding sleeve. But as we increase speed, let's increase now to 200 r p in the arms have moved further away. They're getting thrown further away by centrifugal force. Now, if we speed it up even further, we can see the arms now really quite far away from the main stem or the spindle. So as we increase in speed, the weights or the fireballs are gonna get thrown further and further away from the central stem on as they do this, they are going to put up this sliding sleeve, which is this section here. Concede the linkages only allow them to travel so far. And as they move out the weights, they're gonna pull this interest, leave upwards. So we've got three different speeds there. 100 rpm, 200 rpm of 300 r p en. On. We know that as a increase in speed, the bulls will get thrown further and further outwards until they reach their maximum limit . So all we do really is taking the speed of the engine on were sort of representing that by this this governor. But the governor has been connected to this leave a type arrangement, can see it's jumping from there to there, and then it's jumping down on if we spin around using coming along here to their to their on Finally, you can see gotta control shaft coming through comes through the wall through the point on . We have here a vows. I said you got here valve looks a bit like a butterfly valve. Very old one. Onda we can do first again. I'll try. Get the government into the picture at the same time, we can see the valve. So seven look. Okay, so the governor has slowed down. Now we're 200 off again on this valve now is only, say, halfway open. So that's something we call throttling. And if we go again, is now pretty much fully open. When we can see the governor and see the arms have come down again, see if it come down further. That's a slow is we go OK, so soon? I can't let's from through that again. Just live with more. Okay, change position. Now it's throttled because it's run a 200 up in on now it's running 300. Let's imagine that's it very, very fast on the valve. He is now closed. So why would we set up that centrifugal governor like that? What's it actually doing? Well, the reason we set it up like that, it's imagine that in this pipe here is a lot of steam. So you're I'm a bit of steam coming along here on it gets stopped by the vowels, which play right. The vowel now is throttled. It's half open, which we know is 200 rpm on. The steam can flow through again. So what's gonna happen now? So look, you go backwards. It's flowing through. However, maybe the engine or whatever is the steam that's coming through there has not taken effect yet, so the engine has not accelerated yet. Imagine we gotta steam injure so we'll keep playing it. Now it's fully open, and if we're allowing all of that steamed, passed through the valves and go to a steam engine, then the steam engine should start to accelerate again. And that's exactly what happens. Look, see, now it's accelerated on now is a brain and maximum speed or near maximum speed. So we want to close the steam inlet valve, and using this arrangement, we can control them out, steam fed to the steam engine. And then if we control amounts thing going to steam engine, we can control the speed off the engine on this is really cool is a very simple way to control the speed of the engine. It means we don't have to have somebody there constantly opening and closing a valve, and it does it'll fully automatically. And that is essentially what centrifugal governor does again. Now we're fully open. One, the engine to increase in speed engines increased. So close the valve it. Now it's going too fast, and we've completely closed a valve. That's it. And it will toggle between these sort of three different positions, and you can set them up so they're a lot more accurate. So the tolerances are sort of a lot finer. For example, imagine you wanted it to operate between 1300 rpm and 1500 rpm in. Then you can set the valve up on the governor to operate like that accordingly. It's a very old design, but very simple. The Victorians really didn't know what they were doing concerning mechanical engineering, and first thing, I find it quite a wonderful piece of machinery. 62. Mechancial Hydraulic Governors: mechanical hydraulic governor. The government controls the fuel ranked position through a combined action of the hydraulic piston on a set of mechanical fly weights, which are driven by the engine blow a chef. The blow image provides an illustration of a functional diagram of the mechanical hydraulic governor. The position of the flyways is determined by the speed of the engine. As the engine increases or decreases speed, the weights move in or out. The movement of the fly waste, due to a change in engine speed, moves a small piston or pilot valve, in the government's hydraulic system. This motion is just flow of hydraulic fluid to a large hydraulic piston or server motor piston. The large hydraulic piston is linked to the fuel rack on its motion resets. If you write for increased or decreased fuel, so let's have a diagram. See it? It looks like this quite a lot going on, but I can assure you it's actually quite simple. You can see here that we've got an engine operating at normal speed. On the most important parts of this diagram are simply the flyways, a pointing upwards on the high pressure. All flow his blocks so always coming in here on its flowing down here. But we have a blockage, and we can see here that the piston is held in position by the oil, which is within the space when we an overspeed condition, the fly weights are thrown outwards. To decide on this motion is gonna pull up this pistol. We're gonna uncover this area year so we can see the channel is now on blocks on all of that oil is going to drain away or a lot of the always going to drain away as the spring pushes the piston downwards. So what we've essentially done is here. We're using the oil to hold the piston up on the oil. Pressure is enough that is overcoming the spring pressure. So it's compressing the spring. Well, over here, you can see we've drained off the all on that means the spring pressures and pushing the piston downwards on. Then we will get a trip or an engine trip, which means it's going to stop the engine. We can also see further down here, though, that if we are under the desired speed, imagine we've got a fixed speed governor, so we want toe constantly maintain a speed of 1500 rpm, for example. And the old is gonna flow in here and it's gonna flow, and it's gonna push the piston upwards on that, then is going to connect to the fuel rack on. We're going to allow more fuel to go to the engine. So essentially were using this piston and the spring arrangement with a bit of oil to control the position off the fuel rack. On this way, we can regulate the amount of fuel going to the engine. So here, normal amount. So the oil is not flowing through here. We've just got a normal amount of oil. Within this space, it's enough to hold up the piston. But it's not so little that the spring pressure can push the piston down. So we're gonna maintain a speed of 1500 rpm, and we can see there to fly away to pointing upwards. If we overspeed flyways, get thrown out to the side that Paul's his piston upwards on, we're going to drain the oil out of this space. The spring pressure then exceeds the oil pressure, so it's gonna push the piston downwards, and that connects to our fuel rack and a sense she tells it to reduce him out. Fuel go into the engine under speed again. Oil coming in on flowing directly to the space underneath the piston, pushing the piston up, overcoming the spring pressure on its telling the fuel wreck, then to allow more fuel to go to the engine. And that's it. So that's essentially how a mechanical hydraulic governor works. Still, quite a simple arrangement. Nothing too dramatic. If you're not using a hydraulic mechanical governor, then you may be strictly using a Elektronik type Governor Elektronik type Governors have sensors normally fitted to fly will on what will actually happen is the sensor is mounted opposite a piece off magnetic material or similar on Every time this piece of magnetic material goes past, the censor is gonna record one revolution. So if the engine's working at 1500 rpm, that means this piece of metal will. This magnetic strip passes a sense of 1500 times a minute. The sense of records up on then sends that information off to the governor, and then the governor corrects a fuel rack. Based upon that information, the speed sensor is quite important And that's why you'll normally see minimum of one, but quite often also to very important, the magnetic material that tells a sensor how fast the engine is rotating is installed in the right position. If it's installed after a gearbox, then you are going to get the wrong speed. Indication. I actually found this out the hard way. Somebody had installed it after a gearbox, and that meant that the rotational speed we were seeing on the screen in the engine control room was only half of the true engine speed. These are problems that typically happen when you first start a brand new engine and you realize there's a lot of things have been installed that have perhaps not been installed correctly. 63. Control Summary: Let's just do a very brief mechanical hydraulic government. Recap. The mechanical or hydraulic governor controls engines. Be about balancing engine speed using mechanical fly weights against hydraulic pressure. As the engine speeds up or slows down the weights. Move the hydraulic plunger in or out. This in turn actuator hydraulic valve, which controls the hydraulic pressure to the buffet piston. The buffer piston is connected to the fuel rack. Therefore, an emotion of the buffet. Piston will control fuel to the cylinder by just in the position of the fuel rack, which regulates him out, fueling the injectors. So that is our summary for a mechanical hydraulic governor. Hopefully, you understand the concept now of how a mechanical hydraulic governor works and also have the old central fuel governors work. 64. End Of Course: Why? So it's nice to see you here at the end of the course. I hope you got a massive benefit out of this course and that you learn a lot. The biggest thing to me, though, is it actually enjoyed the course on as you're going through it. The pace was good on you were picking up a lot of new knowledge or perhaps reinforcing what you already knew. If you've got any questions, comments or feedback, please do shoot me a message. I'd be more than keen to hear what you've got to say. Thank you very much again for taking the time to complete this course. I really do appreciate it on our hope to see you on the course in the future. Thanks very much for your time.