Abstract: An automatic decompression system for an internal combustion engine, especially a one-cylinder diesel engine, with at least one outlet and one inlet valve, which are activated by a camshaft (20) with at least one cam (1), wherein the outlet valve is lifted during starting to reduce the cranking resistance, wherein there is provided for lifting the outlet valve at speeds below a switching speed for changeover from decompression to compression a fully automatic lifting device, which engages in the cam (1) of the outlet valve and effects lifting of the outlet valve from the valve seat, wherein the lifting device is equipped with a bow-shaped member (22), pivoted in articulated relationship, disposed between cam (1) and a cam disk (2), which bow-shaped member has two articulated arms (11) and a crosspiece (14) joining them, and which at speeds below the switching speed occupies in the cam plane an engaged decompression position, in which it projects beyond the cam base circle, and which can be disengaged into a n