Self-retracting hydraulic engine brake system

摘要

An exhaust valve rocker arm assembly operable in a combustion engine mode and a decompression engine braking mode includes a rocker shaft 34 and a rocker arm 40. The rocker shaft defines a pressurized oil supply conduit 186 and the rocker arm is configured to rotate around the shaft. The rocker arm also has an oil supply passage 182. A valve bridge 42 engages a first 50 and second 52 exhaust valves. In a braking mode, pressurized oil is communicated through the oil supply conduit, through the rocker arm oil passage to an actuation capsule assembly disposed on the rocker arm and against an actuator such that a plunger acts on the valve bridge 42. During rotation of the rocker arm to a first angle opening the first valve 50 moves a predetermined distance while the second valve 52 remains closed. The assembly provides an advantage over the prior art because both valves are able to close correctly.