Abstract: A method and apparatus for resetting a valve lift for use in an engine brake. A brake piston (160), and a hydraulic fluid passage (214) are arranged within a rocker arm (210) or a valve bridge (400) of an engine. A resetting valve arranged between the rocker arm (210) and the valve bridge (400) is driven by a change in the distance between the rocker arm (210) and the valve bridge (400). When the valve lift of an engine exhaust valve (300) reaches a maximum, a reset fluid passage (219) is opened, the hydraulic pressure within the hydraulic fluid passage is released, the brake piston (160) is reversed by one interval, the motion transmission between a cam (230) and the engine exhaust valve (300) is partially disengaged, and the valve lift of the engine exhaust valve (300) is reduced.

Abstract: A fixed chain engine braking device includes a brake box, a driving mechanism and a braking mechanism. One upright blind hole and one horizontal blind hole are placed in the brake box, and the upright blind hole intersects the horizontal blind hole orthogonally. The driving mechanism includes a rolling ball and/or a driving piston placed in the horizontal blind hole, the braking mechanism includes a braking plunger placed in the upright blind hole. A fluid passage is placed in the brake box, and the fluid passage is communicated with the entry of the horizontal blind hole.