2. Camshaftless engines

2.1 Evolution of distribution kinematics for a reciprocating engine

The opening and closing of an internal combustion engine's valves has been controlled for ages by a camshaft, with a system that has evolved over time, but is still based on the same logic. Initially, each cam actuated a rod which controlled a rocker arm, opening and closing one of the valves by means of a rocking movement. By integrating the camshaft into the cylinder head, automakers succeeded in doing away with this rod, bringing the camshaft closer to the rocker arm. Later, the rocker arm was eliminated thanks to direct-attack cams, which then actuate the valves themselves.