GB772414A - A new or improved door lock - Google Patents

Abstract

772,414. Master-key locks; barrel locks. BACKHOUSE, H. T. Nov. 15, 1955, No. 32693/55. Class 44. Relates to a door lock having a casing 10, a bolt 11 supported in the casing for sliding movement between a position in which it extends from the casing for engagement in a keeper or the like and a position in which it is at least partly withdrawn from the casing, handleoperated means for one side of the door for locking the bolt in its extended position and for unlocking the bolt, and independently operable bolt-withdrawing means for the other side of the door requiring a key for their operation. According to the invention, the withdrawing means are operable by one form of key (a guest key) provided that the bolt is not locked by the locking means and the two means are arranged for joint operation by a key (a master key) of a different form whereby the master key may be employed, when the bolt is locked, to unlock the locking means and to withdraw the bolt. As shown, the bolt is retractable against a spring 13 by a lever 12 attached to a handle spindle 14. A block 16 within the casing 10 carries, on a pivot 20, a lever 18 and a pawl 19. A cylinder 31 of a cylinder lock 28 rotatable by a key 32, carries a cam 33 which is arranged to rock the lever 18 to withdraw the bolt 11, and a cylindrical part 36 rotatable by means of a handle 37, carries a cam 38 which is arranged to move the pawl 19 from the position shown in Fig. 1 to that shown in Fig. 2, against a spring 40, whereby to lock the bolt 11. The pawl 19 is returned to the unlocked position by rotation of the handle 37 in the reverse direction or by master key 45 which engages the part 36 in addition to operating the cylinder lock 28. The bolt 11 may be held withdrawn by operation of the handle 37 to engage the pawl in front of an abutment 25 on the bolt.