Cam follower for the variable actuation of a gas-exchange valve of an internal combustion engine

The cam follower has a roller, which is movable, between a first axial position and a second axial position and which alternately transmits elevations, which are different from one another. The cam has a cylinder-piston unit, which has a pressure medium space for moving the roller from the first axial position into the second axial position, and a spring means for moving the roller from the second axial position into the first axial position. The piston of the cylinder-piston unit is the roller and the roller has an end wall, which delimits the pressure medium space, and an annular collar which extends from said end wall and whose outer lateral surface serves as a cam pick-off surface. The inner lateral surface of the annular collar surrounds an outer section of the cylinder of the cylinder-piston unit.