The camshaft is a rotating shaft (or shafts) in an engine that activates the intake and exhaust valves for each cylinder. As the shaft turns, cams along its length press down on the spring-loaded valves in synchronicity with the motion of the pistons and firing of the spark plugs. An engine may have one camshaft to operate all the valves or separate shafts for intake and exhaust valves. Overhead-camshaft engines have separate shafts for each cylinder bank, so a V-configuration engine like a V-6 or V-8 can have two or four camshafts.
