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HOW WHEELS AND TYRES WORK
CarPoint looks beyond the jargon to understand why your car needs wheels and tyres.
WHAT'S A WHEEL FOR?
It might seem obvious, but a car's wheel needs to receive drive from the engine, other wise you a have a very pretty but expensive way of rolling down hills in comfort. So, starting from the wheel itself and working backwards, you need a hub which will spin freely and has bolts -- arranged in a number of patterns -- for attaching the wheel, or detaching it if the tyre goes flat. It will also have some sort of spinning disc or drum which can be grabbed by a high friction device called a brake. Very important, this bit.
The whole assembly has to be attached to the car, or located, and that's done by a variety of metal arms collectively called suspension, which also have to move as the wheel bounces over bumps, or the car changes direction and leans in any number of ways. There will also be some sort of spring to absorb shock, and a damper to restrict uncontrolled bouncing. Running straight into the centre will be a rotating drive shaft that takes engine power from the gearbox via some sort of differential that allows the wheels to rotate at different speeds when the car turns a corner.
Funnily enough, most cars only have two wheels that are driven by the engine, and they can be either at the front or back, while the other pair just tag along for the ride. How do you tell whether a car has front or rear-wheel drive? Well, you can't without either prior knowledge, a look underneath for drive shafts, or an intimate knowledge of the driving characteristics of the two systems.
If you have no idea whether you're car is front or rear-wheel drive, it might be worth asking someone because it can affect how the car should be driven in extreme or emergency manoeuvres, and to which end snow chains should be fitted for added traction.
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