GB797775A - Locks or latches for doors - Google Patents

Abstract

797,775. Latches. PARKES & SONS. Ltd., J., and BUTTER, F. J. Oct. 1, 1956 [April 25, 1956], No. 12615/56. Class 44 Relates to tubular mortice latches operable by a spring-loaded retractor which can be actuated by either of two roll backs associated with knobs on opposite sides of a door and in which, when a push button on the inside knob is operated, prevents the outside knob from being turned, the outside knob being releasable by turning the inside knob or by pushing on the latch bolt. According to the invention, in such a latch in which normal operation of the retractor by either knob-actuated roll back directly. withdraws the bolt against the combined load of bolt and retractor springs, but direct forcing in of the bolt as by riding over the usual striking plate when slamming the door, does not impose the spring loading of the retractor upon the bolt, such permitted inward movement of the latch bolt independently of the retractor, is utilized in the event of the outside knob being locked against turning by pressing the button in the inside knob, to operate a spring-loaded catch so as to release the outside knob for turning, the catch being carried by the retractor whereby the knob-locking mechanism may also be released by turning the inside knob and thereby operating the retractor to retract the latch bolt. As shown, a spring-loaded retractor 10, which is actuatable by either of two roll backs 11, 12 associated with outside and inside knobs 13 and 14 respectively, is formed with claws 20 which engage a bolt tail 21 of a forwardly spring-loaded latch bolt. A push-button 23 in the knob 14 is fixed to one end of a slidable spindle 24, the other end of which carries a non- circular block 25 engaged in a non-circular hole in a fixed stop plate 26. An extension of the block 25 engages a non-circular hole in the roll back 11 when the push button is pressed inwardly against spring-loading to lock the knob 13 against turning. When so locked, a notch 27 on the spindle 24 is engaged by a spring-loaded catch 28, slidably mounted in the retractor 10 to retain the spindle in the locking position. In operation the catch 28 may be released by turning knob 14 or by pressing the bolt 21 inwardly either of which causes the bolt 21 to disengage the catch from the notch 27, thus freeing the knob 13. In an emergency the catch 28 may be disengaged by a spring-loaded bar 29 engaged by an instrument inserted through an aperture in the knob 13.