GB233123A - Improvements relating to locks and latches - Google Patents

Abstract

233,123. Leitch, J. L. F. April 15, 1924. Locks, permutation.-A combination lock of the type in which the locking discs are set by setting discs, has a pair of superimposed discs normally connected by pins, but which can slide one on the other to release the bolt when the discs are set to align breaks in the pins with the surfaces of the block so that they can slide. The invention is shown applied to a night latch, the bolt of which is withdrawn by sliding the block 15 by means of the finger piece 15<b>, the rod 15<a> being connected to the bolt. Before the block 15 can be slid, the breaks between the pairs of pins 13, 10 must be aligned with the contacting surfaces of the sliding block 15 and the fixed block 12. The pins are correctly adjusted by turning wheels 7 which have irregular peripheries and are eccentrically pivoted on a shaft 8, a definite position of each wheel lifting each pin 10 the correct amount. The wheels 7 are normally held in a " zero " position by springs 24 coiled round the shaft 8. The wheels 7 are set by turning the milled discs 1 mounted on the shaft 2 and protruding through the casing 3, these discs and the wheels 7 each carrying a pulley over which travels the band 6 which bears the characters indicating the combination. The discs 1 are turned until certain characters on the bands are visible through gaps 9 in the casing. The wheels 7 have then each been rotated to the correct position for aligning the breaks in the pins 13, 10 for allowing the block 15 to slide to release the bolt. Pawls 20 pivoted on a shaft 22 engage ratchet wheels 21 on the wheels 7 to prevent these being brought to " zero " position by the springs 24 during setting. When the block 15 is moved to withdraw the bolt, an arm on the member 15a carrying cams 23 causes these cams to release the pawls 20 from the ratchet wheels 21 by engaging the tails 20a of the pawls, so allowing the springs 24 to return the wheels 7 to the " zero " position, scattering the combination. The block 12 can be removed for interchanging the pins 10 for changing the combination. These pins may be set so that the breaks of some of them are normally in correct position for sliding the block 15, so that if these are moved by an unauthorized person attempting to pick the lock re-locking is effected.