A wheel and axle is really just a lever in 360 degrees. That’s why turning a doorknob is so easy.

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A screwdriver is a wheel and axle.

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Cams are in every gas engine. A cam is a mechanism that turns a variously shaped disk on an axel and a follower follows its edge. A cam has an eccentric cam, axle, follower and a bearing. The cam will lift the valve, and it lets gasoline in. The gas will explode. The other cam will go down and another cam will be timed to go up when the other goes down and it lets out exhaust and as the gas explodes it lifts the piston. It creates a system that happens overtime. This is how your engine runs in a car (except Tesla’s). ————————————————————————————————————————