The smooth running of an engine is dependent on a camshaft which precisely manages the flow of energy that enters and leaves.
The flow of fuel and air through an engine is controlled by the opening and closing of valves.
The timing of this is crucial and is dictated by an object known as a camshaft. The technology behind the camshaft has been used for hundreds of years in a range of different devices, including water clocks, and it is the rotation of this important engine part that forces the valves open and shut at regular intervals.
A camshaft is mounted at the top of the engine. Along its length are lobes, which push on rocker arms as it rotates. At the other end of these are valves, which move up and down as the rocker arms push on them, opening and closing as they move.
The rotation and timing of a camshaft is in turn controlled by the rotation of the crankshaft, which is the main drive section at the bottom of the engine. A timing chain or belt stretches from the crank to the cam, so that the two move in unison.
Many cars have two sets of inlet and exhaust valves to get more air and fuel in and out of the engine. This requires double overhead cams; the main timing belt drives one cam, with a short intermediate chain connecting the second. (More Secrets Of Camshaft Power)