Patent ID: 7984705

Claim:
Apparatus for converting an internal combustion engine from a normal engine operation to an engine braking operation, the engine having an exhaust valve train comprising two valves, a valve bridge and a cam for cyclically opening and closing the two valves, said apparatus comprising: (a) an actuator comprising two braking pistons slidably disposed in said valve bridge between an inoperative position and an operative position; in said inoperative position, a gap being formed between said valve bridge and each of the two valves for skipping the motion from the lower portion of the cam, and in said operative position, a linkage being formed between said valve bridge and each of the two valves so that the motion from the whole cam can be transmitted to the two valves; (b) a flow control valve for supplying control fluid with two levels of pressure to said actuator, said two levels of pressure comprising a first level pressure and a second level pressure, and said first level pressure being lower than said second level pressure; and a supporting mechanism for preventing said exhaust valve train from having no-follow, said supporting mechanism comprising a supporting spring and a spring seat; said supporting spring biasing said spring seat to a spring retainer so that the two braking pistons are not loaded by said supporting spring, and said spring seat holding said valve bridge so that said gap can be formed between said valve bridge and the two valves.