GB1440253A - Cylindrical lock set - Google Patents

Abstract

1440253 Locks EMHART CORP 17 Sept 1973 [26 Sept 1972] 43470/73 Heading E2A A latch-bolt 20 is retracted by a followeroperated slider 44 sliding in plastics guides 57 against spring 86 when laterally projecting cams 80 are engaged by follower surfaces 92 cut from the hollow handle spindles 88, 89 (called 'rollbacks'), by rotation of handles 96, 97 in either direction. A locking arrangement 100, operable from inside the door, comprises an arm 121 lying a slot 28 in the casing and, when in the upward, locking position shown, also in a slot 91 in the handle spindle 89 to prevent its rotation. This arm is resiliently (124) secured to a strip 102 passing through slot (84) in the slider to a manually operable control knob 111 and biasing spring 118. Retraction of the latch bolt, even when locked thus from the inside, may be achieved by a barrel lock (not shown) in the open end of hollow spindle 89 operating an inner, auxiliary follower sleeve 126 also having cam surfaces acting on the slider cams 80. The slider is connected by a rod 74 and head 76 to a yoke 160 so as to be able to retract it. This yoke is connected to the bolt 20, with lost motion, by pin 156 acting in slot 158. If a picking tool 184 is inserted to retract the bolt when in its fastening position, this lost motion is taken up to cause a ramp depression 168 to displace a follower 178 down into notches 182 to block further retraction of the latch-bolt. An auxiliary bolt 142 is notched to allow passage of this follower when it is held in retracted position by keeper face 138, but prevents it blocking the normal latching operation.