Abstract: In controlling valve motions of an internal combustion engine, after determining that engine braking operation has been initiated, a deactivation mechanism disposed within a main valve train is activated thereby disabling conveyance of main valve events from a main valve motion source to a valve via the main valve train. Engine braking valve events are enabled for the valve, which may include two-stroke engine braking. Coupling mechanisms, including one-way coupling mechanisms, between adjacent rocker arms may be used in this manner.

Abstract: An engine valve actuation system is disclosed, which is capable providing compression release engine braking in combination with exhaust gas recirculation while maintaining main exhaust and main intake valve events of constant magnitude during both positive power and engine braking. The system is also capable of providing a constant level of desired overlap between main exhaust and main intake valve events during both positive power and engine braking. The system may provide the foregoing functions by using first and second valve actuation subsystems to provide the full spectrum of exhaust valve motions. Both the first and second subsystems may receive an input motion from a valve train element. The first subsystem operates only when the engine braking system is enabled. The second subsystem operates both during positive power and during engine braking.