Abstract: Lost motion variable valve timing systems using hydraulic actuators controlled by a single control valve, preferably an electronically controlled solenoid valve, for actuating two or more valves on similar or identical timing and lift curves include prevention means that stop discharge pulses from one actuator being transmitted to and adversely affecting another actuator connected to the same control valve. Such prevention means may include one way check valves in the discharge lines connected with the control valve, non-aligned multiple inlet ports in the control valve and positioned to avoid transfer of pulses from one inlet port to another, or other return pulse preventing means.

Abstract: A lost motion hydraulic actuator for use between a cam and a valve of an internal combustion engine is provided with internal communication ports that are controlled by a piston to provide sequential closing of the ports during closing of the engine valve to reduce hydraulic shock and hammering noise as fluid is gradually directed exclusively through a damping orifice during valve seating.

Abstract: A damping mechanism for a lost motion hydraulic actuator utilizes a thin edge orifice in cooperation with a communication passageway between the upper and lower chambers controls the damping of the upper piston on closure. The upper piston is operatively connected to the engine valve of an internal combustion engine. A communication port from the upper chamber to the communication passageway is closed off as the upper piston returns to its normal position forcing the flow of the hydraulic fluid through the thin edge orifice. In this manner the viscosity of the hydraulic fluid does not control the damping of the actuator and the noise factor is substantially reduced.

Abstract: The O-ring seal at the tip end of a particular model of fuel injector is replaced by an adapter grommet which provides an axial seal. This makes the fuel injector interchangeable with another model of fuel injector that is specifically designed for an axial seal. The adapter grommet comprises a radially inner portion disposed in the injector tip's circular groove that was orignally intended for the O-ring seal, and a radially outer portion that axially overlaps both the groove and a portion of the tip that is distal to the groove. The radially outer portion of the adapter grommet provides the axial seal with the shoulder of a hole into which the tip is inserted.