Abstract: An improved engine retarder of the compression release type in which the exhaust valves are opened near the end of the compression stroke of the engine by a slave piston hydraulically interconnected with a master piston driven by an existing pushtube is provided. The improved engine retarder includes a second master piston interconnected hydraulically in parallel with the first master piston and driven by a separate existing pushtube whereby the timing of the compression release event may be regulated and the stress on the engine pushtubes may be reduced.

Abstract: An improved method and apparatus for a compression release engine retarder is disclosed. The method and apparatus are used in conjuction with a supercharged internal combustion engine fitted with a compression release engine retarder and a supercharger employing a divided volute exhaust gas turbine. A diverter valve is located between the exhaust manifold of the engine and the exhaust gas turbine. Upon actuation of the compression release engine retarder, all of the exhaust gas (or air) passing through the exhaust manifold is diverted to the portion of the divided volute of the turbine which is closest to the turbine wheel flange and, within that portion to the divided volute, to the region closest to the center of rotation of the turbine wheel.

Abstract: An improved compression release engine braking system is provided for internal combustion engines having two exhaust valves associated with each cylinder. The slave piston of the compression release brake is relocated so as to register with one of the two exhaust valves and the crosshead assembly is modified so that actuation of the exhaust valve rocker arms will open both exhaust valves in the normal manner during the fueling mode of engine operation while the slave piston of the compression release brake will open only one of the exhaust valves during the engine braking mode of engine operation.

Abstract: An hydraulic slave piston return mechanism is provided for an engine retarder of the compression relief type. The mechanism senses the position of the slave piston at the time when the engine exhaust valve has been opened. At this point, the hydraulic pressure on the slave piston is equalized by opening a passageway through the slave piston to an accumulator whereupon the engine exhaust valve spring immediately closes the exhaust valve. Thereafter, the accumulator returns the hydraulic fluid to the hydraulic circuit. The mechanism assures that the exhaust valve opened near the end of the compression stroke to produce the desired engine retarding effect is closed prior to the end of the expansion stroke without affecting the retarding horsepower produced by the engine retarder or the normal functioning of the exhaust valve during the exhaust stroke of the engine.