Patent GB-1302192-A (GB)
IPC: B60R25/021
Filed: 1969-03-11
Abstract: 1302192 Anti-theft devices WILMOTBREEDEN Ltd 10 March 1970 [11 March 1969 6 Jan 1970] 12813/69 and 618/70 Heading B7J [Also in Division E2] A cam-and-slide mechanism for an antitheft locking device for mounting on the steering column of a motor vehicle comprises a housing 1 which at the front is adapted to house a key operated lock structure 4 and which at the rear provides a mounting for a switch mechanism 5, an operating shaft 10 adapted to couple the lock structure and the switch mechanism when fitted which passes through a locking slide 13 which is arranged at intermediate position within the housing and a cam 11 which controls movement of the slide and which is mounted or formed on the shaft on the rear side of the slide. In the construction shown the lock structure 4 includes a non- rotatable lock body 8 and a lock cylinder 9 which is rotatable in the body 8 the structure 4 being depressable as a whole within the housing and the cylinder 9 being coupled to the shaft 10 via a member 17 which projects from the cylinder 9 and is slidable in and rotationally coupled to the shaft 10. The cam 11 is retained in the housing between a transverse wall 31 and a retaining ring 32 through which the shaft 10 passes, the ring 32 being peened in position within the housing 1 to withstand the rearward thrust of a spring 18 within the shaft 10 which urges the member 17 and thus the lock structure to a normal outward position. The cam 11 engages a projection 12 of the slide 13 to retract and hold off the slide against two side springs 14 urging it to the locking position. When the key is inserted into the lock cylinder 9 its tip enters a recess in the adjacent face of a member 16 and it is then positioned radially inwardly of a detent 23 which is radially slidable in a radial recess in a member 16 which is in the form of moulded plastics ring mounted on the inner end of the cylinder 9 so as to turn therewith. The tip of the key prevents the detent 23 moving inwardly against the spring 21 so that it is unable to clear a projection 25 of the housing and thus prevents the lock structure moving inwardly. The key can only be entered into the lock cylinder 9 in the locking position of the cylinder and from that position the cylinder can be turned to an "auxiliary" switch position and from thence to "ignition" and "start" switch positions. During the movement from the "locking" position to the "start" position the slide 13 is retracted by the cam 11. From the "start" position the lock cylinder can be turned back to the "ignition" position and from thence to the "auxiliary" position; in that position a tongue 19 of the member 16 fouls a member 26 which is slidably mounted in the housing so preventing further movement until the key is depressed with the lock structure sufficiently for the tongue 19 to clear the member 26 after which the key can be turned to the "locking" position in which until the key is withdrawn the vehicle is not locked since the tongue 19 in the depressed position of the lock structure is disposed underneath a face 20 of the slide to hold off the latter against the spring 14. The lock structure can only be depressed in the "auxiliary" switch position since in the other position the tongue 19 engages an annular abutment face 22 in the housing, the face 22 being cut away to allow passage of the tongue only in the "auxiliary" switch position. As the key is turned after depression towards the locking position the detent 23 moves behind and engages the housing projection 25 and as the tip of the key prevents inward movement of the detent 23, the lock structure is retained in the depressed position but the member 16 holding off the slide. On withdrawal of the key the detent 23 is free to move inwardly against the spring 21 sufficiently to clear the housing projection 25 and this allows movement of the lock structure to its outward position under the action of the spring 18. The detent 23 has a chamfered front face and the projection 25 has a chamfered back face to allow the detent to pass the projection. In a modification axial location and retention of the cam 11 against forward movement is again provided by an apertured transverse wall but the retaining ring is replaced by two internally projecting lugs moulded integrally with the housing 1, the cam 11 has a generally circular periphery over a rear portion which takes a bearing in the bore, the profile being peripherally notched in two diametrically opposed positions so that it can be inserted past the retaining lugs and then turn to a retained position. An aperture in the housing which allows the slide to be inserted is closed by a cover-plate 28 peened in place and this carries a terminal block 34 which supports an external terminal 35 and has an inwardly projecting contact plunger 36 which completes an electrical circuit from the terminal 35 to earth via the slide 13 whenever the slide is retracted.