Patent GB-493768-A (GB)
Title: Improvements in lock mechanism
IPC: E05B65/22
Filed: 1937-04-10
Abstract: 493,768. Latch mechanism. SLEIGH, H. L., CHESTON, A. S., and BOOTH, J. H. April 10, 1937, No. 10258. [Class 44] A latch mechanism has a bolt capable of sliding movement to retract it from its projected position and also capable of pivotal movement about an axis transverse to the direction of sliding movement. The bolt 13 of an automobile door latch, Figs. 1, 2, is guided by a pin 15 in the casing engaging a slot 14 in the bolt. The casing comprises an L-shaped plate 11, of which the shorter limb 12, which has a slot 16 for the bolt, is disposed on the edge of the door, and a diecast plate 10, riveted to the plate 11. The slot 16 is wider than the bolt 13 and an integral part 17 of the plate 10 projects into the slot to stiffen the casing. The slot 16 is also deeper than the bolt 13 to allow the bolt to execute pivotal movements about the pin 15. The keeper 39, Figs. 2 and 4, has a main catch face 41 and a safety catch face 40, the bottom edges of which are joined by an incline 38, and the bolt has a bevelled under-surface 37 as well as a bevelled end so that as the door closes the bolt is first pressed inwards until it engages the face 40, and then pivoted upwards by the incline 38 until it reaches the face 41. The bolt may be retracted by a follower 20 operated by the outside handle or by a follower 24 operated by the inside handle. The bolt is projected and the handles are held in their normal positions by a spring 31 stretched between a vertically disposed lever 32, pivoted to the casing at 33 and having its free end in contact with the tail of the bolt, and an horizontally disposed lever 29, pivoted to the casing at 30, the free end 28 of this lever engaging a notch 26 on the boss of the follower 24. A spring 36 engages a notch 35 on the follower 20 to keep it in place when the bolt is operated by the inside handle. A buffer 43 consisting of a spring-pressed sheet metal cap mounted in a bore 44 in the casing urges the bolt downwards to prevent rattle when the door is closed. The latch may be blocked against operation by the outside handle by turning the inside handle in the reverse direction so that its follower 24 engages a notch 34 on the follower 20, the end 28 of the lever 29 riding, during this movement, over the projection 27 on the follower 24. A remote inside handle, connected to its follower spindle by a link, may be used. The periphery of the boss of the follower 24, over which the end 28 of the lever 29 travels during retraction of the bolt by the inside handle, may be formed as a cam so as to vary the tension of the spring 31 according to the position of the bolt. The cam may be arranged to increase the tension of the spring when the bolt is in the retracted position. In a modification, Fig. 5, the bolt 50 has a slot 51 by which it is mounted for sliding and pivotal movement relative to the follower boss 52. The follower 54 engages a vertical face 55 on the bolt to retract it, the spindle 53 carrying a handle on one or each side of the door. A tension spring 56, connected between a lug on the bolt and a lug fixed to the casing, projects the bolt and urges the follower to its normal position in which it rests against a stop 59. A second spring 57 takes the place of the spring pressed buffer of the first modification. A projection 60 on the lower edge of the bolt co-operates with a lug 61 in the casing to deflect the bolt upwards as it is being retracted. The positions of the operating spindles may be varied and the casing may be modified for use as a mortise lock on the doors of buildings.