The crank gear (A) is exactly half the size of the cam gear (B). The cam turns only one revolution for every two revolutions of the crank. This is so the exhaust and intake valves will open and dose ...

'It seems pretty simple, one shaft turning another, and with gears, chains, or belts, there are a variety of devices for getting the job done. We're talking about the camshaft, and there are a variety ...