GB618492A - Improvements in locks - Google Patents

Abstract

618,492. Door latches. MITCHELL, A. R. March 10, 1947, Nos. 6648 and 18299. Divided out of 618,490. [Class 44] In a door-latch, the spring actuated bolt 9, is retractable by an outside key lock and an inside handle, and there is provided a safety device to dead-lock the inside handle, manually operable by means located on the inner-side or on the edge of the door and restorable to the inoperative position by retraction of the bolt by the outside key lock, or from the inner side by use of a key which is preferably that of the lock itself. The device comprises a pawl 17 pivoted at 16 and adapted to engage the latch actuating cams 11 and 13 associated with the inside handle and the outside lock respectively. That part of the pawl 17. engaging the cam 11 is of dovetail shape and engages in a similar shaped recess. That part engaging the cam 13 is of V-shape and engages in a V-shaped recess. Another arm of the pawl has two notches co-operating with a spring loaded pin 19 which retains the pawl in either the operative or inoperative position. The pawl is moved into operative position by finger pressure on a sliding rod 18 whose end is in an inaccessible position on the edge of the door, covered by the staple casing when the door is shut to prevent inadvertent locking. The end is further protected by a thin spring strip 20. In this position, the cam 11 on the inside handle is locked by the dovetailed end of the pawl but the cam on the outside lock may still be turned and will force the pawl into the inoperative position shown. The pawl may be released from the inside by a sliding. bar 21 operable by a button but normally locked by two springs loaded gated tumblers 22 disposed in slots in the bar 21 which are released when the key is inserted in the hole 25. A single spring 24 loads both tumblers and urges the bar 21 outwardly. Specification 618,490 is referredto.