Camshaft arrangement having a deactivatable cam

A camshaft arrangement having at least one deactivatable cam comprising a camshaft, a cam rotatably supported on the camshaft and having a coupling recess facing the camshaft with a pressure relief opening, a hydraulically actuatable coupling for selective establishment of a rotationally fixed connection between the cam and the camshaft including a transverse recess in the camshaft, a coupling pin displaceable in the transverse recess between a coupling position in which it engages the coupling recess in the cam to establish the rotationally fixed connection with the cam and a release position in which it is retracted from the coupling recess to disconnect the rotationally fixed connection, the coupling pin having a surface facing the bottom of the camshaft transverse recess which, together with the camshaft transverse recess, forms a pressure chamber, connecting passage means to supply hydraulic fluid to the pressure chamber, an axially displaceable control piston forming a variable-volume compression chamber communicating with the connecting passage means to control the pressure in the pressure chamber, and pressure relief passage means for relieving the hydraulic pressure in the compression chamber when the control piston has moved to a position reducing the volume of the compression chamber.