GB1440943A - Locking devices - Google Patents

Abstract

1440943 Locks LOWE & FLETCHER Ltd 25 Jan 1974 [1 Feb 1973] 5016/73 Heading E2A In an anti-theft lock of the kind in which outward axial movement of the lock-barrel 16 controls movement of the bolt 15 to its fastening position, this is prevented, until the key 22 is withdrawn, by a roller 39 protruding into the keyway 23 and acting on a follower 40 engaging an abutment 41 on the lock casing. Insertion of the key moves or retains the roller in its displaced position. Fig. 2. Rotation of the key and barrel by 30‹ causes the follower 40 to clear the abutment 41 to permit inward axial movement of the barrel under the influence of cam surfaces (45 and 46, not visible) on the barrel and housing respectively. The axial movement of the barrel is complete at 50‹, at which angle the bolt 15 has been completely withdrawn by a cam 26 driven by the barrel. The inward axial movement of the barrel causes a flange 38 on the barrel to allow similar axial movement of a spring-loaded detent 31 which engages under a ledge 33 on the bolt to hold it up against return springs 34. Axial movement of the barrel allows a spring-loaded pin 47 to engage in a circumferential groove 49 in the barrel to prevent its return movement. Further angular movement of the barrel actuates the contacts of switch 13 (not shown) in the usual sequence. When the barrel is returned by the key to its initial position, a ramp 50 is presented to the pin 47 so that it may be forced up clear of the groove 49 by barrel return spring 44. However, the barrel cannot move back because the follower is held against the abutment 41, as shown in Fig. 3, by the presence of the key in its slot. When the key is withdrawn, Fig. 4, the follower may pass over the abutment. Axial movement of the barrel causes flange 38 to draw back the detent 31, thus allowing descent of the bolt.