Abstract: A valve control apparatus particularly suited for a diesel engine brake. There is an hydraulic actuator having a piston which contacts the valve stem of an exhaust valve. The actuator is independent of the exhaust valve opening mechanism. There is a device, such as an electromagnetically activated valve, which can releasably shut off a flow of fluid from the hydraulic actuator after the exhaust valve is opened by the exhaust valve opening mechanism. The exhaust valve is prevented from closing until a flow of fluid from the hydraulic cylinder is permitted just before top dead center of the compression stroke.

Abstract: A method and apparatus for braking a multicylinder diesel engine. Some compressed gases are released from each engine cylinder near top dead center of each compression stroke on each cycle of the engine by forcing open the exhaust valve with a slave piston assembly of a two-stage master and slave cylinder combination. The slave piston assembly is moved by a master piston assembly which operatively engages an engine component which moves prior to top dead center of each compression stroke. The ratio of the area of the master piston assembly to the slave piston assembly is then increased and the exhaust valve is then opened to a preset fully cracked open position during a second stage of the master and slave cylinder combination. Loading on the engine component is reduced during the first stage and the rate of opening the exhaust valve is increased during the second stage when the force required to further open the exhaust valve has been reduced.

Abstract: A compression relieve type braking apparatus comprising a slave piston, a master piston, a housing defining a first passageway, and a pressure release mechanism. The first passageway interconnects the master piston and the slave piston. The master piston is responsive to the engine cycle in a manner to move between a first master piston position and a second master piston position. The pressure release means is responsive to positioning of the master piston in a manner to relieve pressure in the first passageway when the matter piston (in moving between the first and second master piston positions) reaches a predetermined relief location. The relief of the pressure acts to cause the exhaust valve to retract.