Abstract

An internal combustion engine that has a camshaft having a plurality of cam lobes, a plurality of valves where each of the valves are actuated by a lifter actuated by the camshaft with a cam lobe. The lifter comprises a lifter body having an upper surface and a lower surface. A cam contact plate pivots on an axis on the upper surface of the lifter body. Opposed hydraulic actuators are present on either side of the axis of the cam contact plate, where each hydraulic actuators comprise a fluid chamber in the lifter body, a piston in the chamber, and a spring biasing the piston into contact with the cam contact plate. The lifter further comprises a line supplying hydraulic fluid to the fluid chambers of the hydraulic actuators and a control valve for controlling fluid flow from one hydraulic actuator to the other hydraulic actuator.