Back Motor de pistons sense arbre de lleves Catalan Motor sin árbol de levas Spanish Espeka-ardatz gabeko pistoi-motor Basque Moteur à piston camless French Motore a pistoni senza camme Italian Kamløs ventilteknologi (forbrenningsmotorer) NB System bezkrzywkowy Polish 无凸轮轴 Chinese
A camless or free-valve piston engine is an engine that has poppet valves operated by means of electromagnetic, hydraulic, or pneumatic actuators instead of conventional cams. Actuators can be used to both open and close valves, or to open valves closed by springs or other means. Camshafts normally have one lobe per valve, with a fixed valve duration and lift. Although many modern engines use camshaft phasing, adjusting the lift and valve duration in a working engine is more difficult. Some manufacturers use systems with more than one cam lobe, but this is still a compromise as only a few profiles can be in operation at once. This is not the case with the camless engine, where lift and valve timing can be adjusted freely from valve to valve and from cycle to cycle. It also allows multiple lift events per cycle and, indeed, no events per cycle—switching off the cylinder entirely.