The camshaft's an apparatus often used in piston engines to operate poppet valves. It consists of a cylindrical rod running the length of the cylinder bank with a number of oblong lobes or cams protruding from it, one for each valve. The cams force the valves open by pressing on the valve, or on some intermediate mechanism, as they rotate. History The first known cam and camshaft were invented in Iraq (Mesopotamia), described by Al-Jazari in 1206. The cam and camshaft later appeared in European… (More on Camshaft)