Abstract: The invention relates to a possibility for the relative rotation of two camshafts for the control of internal combustion engines, more particularly to reduce the gas exchange losses of reciprocating 4-stroke engines. The invention more particularly enables very large adjustment angles of up to 220.degree. crank angle to be obtained.

Abstract: Two camshafts 1 and 2 have cams which act through levers 3 and 5 and followers 7 and 8 on one or more valves 4 spring-loaded in the closing direction. One of the two camshafts determines the opening function and the other camshaft the closing function of the valve, so that through a phase shift of the camshafts with respect to one another, the stroke and the timing of the valve or valves can be varied in a wide range. The first camshaft (1) acts upon a drag lever (5) and the second camshaft (2) acts on a rocker lever (3) whose fulcrum is fixed to the drag lever. The axis of rotation of one of the camshafts is at least approximately in the extension of the longitudinal axis of the valve, and the frame-fixed fulcrum (P1) of the drag lever 5 and the fulcrum (P2) for the rocker lever (3) are disposed on opposite sides of the longitudinal axis of the valve. This makes it possible to create an especially compact, light and rigid construction of the valve gear.