Patent GB-502369-A (GB)
Title: Improvements relating to door and like fastenings
IPC: E05B57/00
Filed: 1937-09-30
Abstract: 502,369. Door latches. LINES, A. Sept. 30, 1937, Nos. 26479/37 and 4563/38. [Class 44] A spring-shot door latch is retractable by a slidable spindle operated by handle levers engaging projections on the spindle, and the spindle is rotatable to move the projections out of engagement with the levers which are thus made inoperative, a further projection on the spindle serving at the same time to block the latch member. As shown, the latch has a casing 2 received in a notch in the door edge, the casing. having an apertured end plate secured to the edge of the door 1 by screws as in a mortise lock, a plate 7, Fig. 1, rigid with the casing and abutting against one face of the door, and a plate 8 adjustable on the casing to abut against the other face of the door. Plates 7, 8 may extend to serve as finger plates and are secured to the door by screws. To allow adjustment, plate 8 is recessed to embrace the casing and has projections 8<1>, Fig. 3, which can be passed into and moved along grooves 2<1>. The latch 12 is pivotally mounted at 13 to swing into engagement with an apartured striking- plate 14 under the action of a spring 15, Fig. 5, and is withdrawn by a sliding spindle 17 operated by Rever handles 18, 19 pivoted on the casing, their short arms 18<1>, 19<1> respectively engaging radial projections 22, 23 on the spindle. Another projection. 16 on the spindle engages and serves to retract the latch. The handles are held in normal position by springs 24, 25. Spindle 17 is in the form of a split tube having radial flanges 17<1>, 17<2> and is slidably mounted on a spindle 26 pivoted in the casing, spindle 26 also being a split tube with flanges 26<2>, 26<1>, more closely arranged than flanges 17<1>, 17<2>, to allow limited lost-motion angular movement as between the spindles. Spindle 26 is rotatable by a suitable key inserted at either end. Locking levers 30 are provided to co-operate with flanges 17<1>, 17<2>, each lever being biassed to locking position by a spring 33. Each lever is of channel form, Fig. 10, one limb 30<1> having a notch to provide shoulders co-operating with the flanges and a projection 30<4> adapted to co-operate with a radial web 17<3> on spindle 17 to hold the spindle locked if a lever be rocked too far by use of an incorrect key. The other limb 30<2> is formed to co-operate with the key bit and has a foot 30‹ by which the lever is rockably mounted. The lost motion between members 17, 26 allows the levers to he disengaged before spindle 17 is rotated. When spindle 17 is rotated from the position shown in Fig. 5 projections 16, 22, 23 are respectively moved out of engagement with latch 12, and arms 18<1>, 19<1>. At the same time a projection 27 on spindle 17 is moved into place between the latch and a fixed abutment 28 to block the latch. The steps on the key-bit are symmetrically arranged to allow use from either side of the door. According to the first Provisional Specification, the latch is blocked by a spring-urged lever released when the spindle is rotated to locking position. According to the second Provisional Specification the locking mechanism comprises segmental transverse plates carried by the spindle, each provided with an arcuate rib which must register with a gap in a corresponding locking lever before the spindle can be rotated, the requisite registration being effected by the action of the proper key on the levers.