Controllable valve tappet for use with dual ramp cam

摘要

A hydraulic tappet or lash adjuster of simplified design is disclosed for use in the valve train of an internal combustion engine equipped with dual ramp cams. In one embodiment, the disclosed tappet is designed to respond to the presence or absence of control pressure supplied through a single supply port to cause variation in the timed relationship of valve opening and piston movement whereby the internal combustion engine may be operated in a power mode or a braking mode. In another embodiment, a pressure relief outlet is provided in the tappet for cooperation with a pressure relief port to insure collapse of the tappet thereby to prevent the valve from being opened beyond a pre-determined fully open position.