Patent GB-280057-A (GB)
Title: Improvements in or relating to locking devices
IPC: E05B65/00
Filed: 1926-12-20
Abstract: 280,057. Express Lift Co., Ltd., and Arnold, D. L. N. Dec. 20, 1926. Fastenings for hinged doors; latches, sliding; striking.plates for latches.- A latch described as for swinging doors for lifts, but applicable to railway-carriage &c. doors, and when suitably modified, to sliding doors is of the kind in which unlocking is made dependent upon the lift being in predetermined position, as at a landing, to co-operate with a fixed ramp or stop device. To avoid noise and wear due to impacts with the stop device, the stop is placed so as normally to be clear of the co-operating lock member and does not itself operate the lock member, but serves as an abutment to give a reaction necessary to releasing the lock by hand operation. The stop 2 is normally clear of a roller 22 carried by a co-operating arm 5 secured to a spindle 7 mounted on bearings in a striking-plate case 9 secured to a door post. Loosely mounted on the spindle 7 is an arm 6 urged in anticlockwise direction, Fig. 1 by a spring 17, Fig. 2 surrounding and secured at one end to the spindle, relative movement being limited by abutment shoulders 18 held in contact by the spring. A latch bolt 28 slidably mounted in a casing carried by the door is shot by a spring 36 into engagement with a recess or aperture 50 in casing 9, outward movement of the bolt being limited by an adjustable stop 41, 42. Depending from the bolt is a pivoted arm 4 the lower end of which is held by spring 31 in engagement with the end of a follower 33 secured to a handleoperated spindle 34. The bolt is normally retained in the shot position by detent 43 rotatable on spindle 34 co-operating with a projection 46 on arm 4. Detent 43 is urged in clockwise direction by spring 72 against a stop 44 on follower 33 so that when the follower is rotated anti-clockwise to release the latch detent 43 moves therewith, the arrangement being such that projection 46 is not released until the permissible movement of the follower is almost completed. Pivoted to arm 4 is a slidable member 47 with a terminal roller 48 adapted to project through openings in the latch casing and casing 9 into 'contact with the upper end of arm 6. When spindle 34 is operated by handle 23 to release the latch, bolt 28 is at first retained against withdrawal by detent 43. Follower 33 thus moves arm 4 about its pivot 29 to project slider 47, 48 and rotate arm 6 clockwise against the action of a spring 24. As movement of spindle 7 is prevented by contact of roller 22 against stop 2, the, spring 17 becomes torsionally stressed. When detent 43 then clears projection 46., the action of springs 24, 17 returns arm 6 and slider 47, arm 4 being thereby rotated anticlockwise about its lower end as a fulcrum, its upper end withdrawing the bolt 28, the action being rapid on release of projection 46. In the absence of stop 2 spindle 7, being free to move, is rotated clockwise, spring 17 is not stressed, and spring 24 is not strong enough alone to effect withdrawal of the bolt against the action of spring 36. The pivotal mounting of detent 43 allows bolt 28 to be returned by spring 36 when the door is opened even if the handle 23 be held, and the end of the bolt is rounded so that the door may be slammed. Locks and fastenings operating electric switches.-The bolt 28 may be utilized when in position in aperture 50 to hold closed an electric switch, which, as described, opens, and is locked in the open position, when the door is opened, and may be used to prevent starting the lift until the door is closed and locked. The end of the bolt engages and moves to the right, Fig. 1, the end 51 of a. switch arm 52 pivoted at 53 in the casing 9 and carrying an insulated contact 54 which bridges contacts 55, 56 pivotally mounted to yield against the action of springs 58, movement bv the springs being limited by the tailpieces 59. Arm 52 is suitably biassed so that when the, bolt 28 is withdrawn .the switch is opened. To prevent tampering when the door is open switch arm 52 is held in open position by a pivoted spring-actuated detent 65 within casing 9 engaging an aperture in the lower end 51 of the arm. The. detent is released when the door is closed by a hook-shaped projection 69 on the latch casing entering a slot 67 in casing 9 and engaging a projection 70 on the detent.