an apparatus for actuating at least one outlet valve of a valve - controlled internal combustion engine for motor vehicles , includes an actuating element which is driven by a camshaft . a first piston ; cylinder unit , preferably a hydraulically loaded piston / cylinder unit , is provided between a cam of the camshaft and at least one outlet valve . the piston / cylinder unit allows at least one outlet valve to be held in a non - closed intermediate position during an engine braking mode with exhaust - gas backpressure . a second piston / cylinder unit is provided which is configured as a valve - play compensation element , preferably as a hydraulic valve - play compensation element . at least one valve train - side device is provided between the cam and the at least one outlet valve , which valve train - side device exerts a force which is directed counter to the adjusting action of the hvc but is lower than the latter .