For driving instructors or those thinking about becoming a driving instructor.
DorWey
Driving School - The Engine
Below you will find a simple explanation of how the engine works. It is not essential that you understand how it works but as the theory is quite simple and knowledge is power I recommend that you take a look at it.
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The way an engine works is surprisingly simple. Imagine that you have two tin cans. One is smaller than the other and will fit snugly inside the larger can. Now imagine that you have some way of introducing an explosive mixture of petrol and air into the space between the two cans and then a way of igniting it. The smaller can would be ejected fairly quickly out of the bigger can. An engine works by harnessing this action. In an engine we would call: 'Can 1', The Cylinder 'Can 2', The Piston. |
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We now need to harness this power. It's all very well having cans flying about all over the place but they could have someone's eye out! To harness this power we use a Connecting Rod to connect 'Can 2' (i.e. The Piston) to a Crankshaft. This not only allows us to use the energy but also to convert the up and down motion into a much more useful circular motion. |
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OK, now we nearly have an engine - only four things are missing.
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A method to get fuel into the cylinder.
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A way of igniting it.
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A way of getting rid of the smoke after the explosion.
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Finally a way of connecting and disconnecting the engine to the car's wheels.
To get fuel into the cylinder and the smoke out, we use valves. To ignite the fuel we use a spark plug. But these three components have to operate at specific times. The answer is the 4-stroke cycle, otherwise known as SUCK - SQUEEZE - BANG - BLOW.
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The Four-stroke Cycle The first stroke or 'Suck'. This is a downwards stroke of the piston. As the piston descends a valve opens and fuel is sucked in. The second stroke or 'Squeeze'. This is the upwards stroke where the valve shuts and the fuel/air mixture is compressed at the top of the airtight cylinder. (Compressed fuel/air gets you a larger explosion for your money. A larger explosion = more power.) The third stroke or 'Bang'. At the top of the the second stroke a spark is triggered across the spark plug which ignites the fuel. The resulting explosion forces the piston back down the cylinder. This is the power stroke. The fourth stroke or 'Blow'. As the piston rises back up the cylinder another valve opens allowing all the gasses to be ejected from the cylinder and then closes again.
When you use the dipstick this is the oil level you are reading.
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The Flywheel |
The Flywheel Attached to the end of the crankshaft is a circular plate called The Flywheel. As this revolves with the crankshaft we can use it to drive the car forwards. To understand how this operates look at the section on how The Clutch works. |
After lubricating the moving parts the oil drains to the bottom of the
engine where it is sucked up and pumped around the system again.
So there we have it, a fully working single cylinder engine. A single cylinder would be OK for a smaller vehicle like a motorbike but we need more power for larger vehicles. The average car has four cylinders with the pistons connected to the same crankshaft. The power strokes (the 'Bang' strokes) are delivered in a way which causes less stress to the engine. (The firing order, if you are interested, is 1-2-4-3 or 1-3-4-2, counting from the cylinder nearest to the flywheel.)
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So that is how the engine works. If you want to see how the engine is connected to the wheels, via the clutch, then click on the link below.
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Copyright Information - January 2002. The copyright of this web site and the downloads found within (apart from third party material) belongs to its author, Paul Pearson ADI - DorWey Driving School. Material may not be reproduced or used in any form or by any means, in whole or in part, without prior written permission from the author. The diagrams and information found on this page are for the exclusive use of DorWey Driving School clients. If any driving instructor or driving school wishes to use any of the material found on this page they must first contact DorWey Driving School.
If anyone finds that this material is being used elsewhere please e-mail DorWey Driving School. E-mail here------> Report