Abstract: A tumbler pin-type cylinder lock wherein the lock cylinder is mounted for controlled axial or axial and radial movement relative to the lock cylinder housing characterized in that the cylinder is provided with a safety cover and the key and the cylinder have cooperating surfaces for axially shifting the cylinder toward a device actuating position. The cooperating surfaces may comprise the first tumbler and a cooperating portion of the key or the most inner end of the key and a cooperating surface on the cylinder. The assembly also includes a fixed pin in the lock housing which engages a track or groove on the cylinder to thereby control the axial and/or axial and radial positioning of the cylinder relative to the lock housing.