In order to enable a turning of a key of a lock cylinder onto a driven member (shaft 36) in the lock cylinder only when a proper key is inserted, yet to prohibit the turning in case of an overload, an overload lock is arranged therebetween. The driven member (shaft 36) should specifically actuate functions in the vehicle only if the correct key is used. A threshold rotation torque determines the change between the normal and the overload state. In order to improve the lock cylinder, it is furnished that a disengaging lever (40) is mounted in the cylinder housing (30) in a pivotable manner (42) and can be displaced between two pivot positions in a radial plane defined by the longitudinal axis (13) of the lock cylinder. A locking cam (41) belonging to the overload lock is arranged on the free end of the disengaging lever (40). When the disengaging lever pivots, a carrier (50) pivots in unison, the carrier having a coupling part which engages in a counter coupling part of the cylinder core (10) during normal function. The disengaging lever (40) and the carrier (50) form a common pivot unit. In case of overload, wherein a rotation of the cylinder core force, the carrier (50) is decoupled from the cylinder core (10).