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The engine is a unique part of the car that moves the car. A mixture of fuel and air is compressed by a piston and is ignited by an electric spark. The fuel and air mixture then explodes and forces the piston down. The other end of the piston is connected to a shaft which rotates and moves the wheels. | |
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A gear box contains two sets of gear wheels. The input and output shafts are on top and the “layshaft” is underneath. When the gear lever is moved the selector rods push certain gear wheels together. If reverse gear is selected, an idler wheel slides between the layshaft and the output shaft.
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Single-seat racing cars and some specialized sports cars have the engine mounted behind the driver. In this position, the engine’s weight is over the wheels it drives, increasing tire grip. It also allows the front of the car to be thinner and lower to reduce air resistance.
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Solid metal wheels were strong but too heavy. Wheels made from steel rims and hubs, linked by wire spokes were tried but were easily damaged. Eventually wheels made from alloys were used and are still used. The wheels are fitted with tires made by mixtures of different rubbers, called the tire compound. Compounds behave differently, some compounds are better on dry roads some are better on wet surfaces.
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In a drum a rough lining material is fixed to the surface of two curved "shoes" inside the drum. Pressing the shoes outward and against the spinning drum slowing it down. In a disk brake, flat friction pads grip a disk that spins with the wheel. The disk can sometimes get so hot that it glows red. |
| If the car was connected to its wheels by rigid shafts and struts it would be uncontrollable at high speeds. The whole car would bounce around over every little bump in the road surface. Every car is therefore linked to its wheels with a system of levers, springs, and pistons called its suspension. This allows the car to absorb the bumps giving the car a smoother ride. |
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