GB483874A - Improvements in or relating to locks - Google Patents

Abstract

483,874. Door locks. VIRANY, G. Feb. 22, 1937, No. 5312. Convention date, Feb. 21, 1936. Addition to 458,341. [Class 44] A latch handle becomes freely rotatable upon its spindle when turned in a direction opposite to its usual opening movement and can only be recoupled to its spindle by a key. A handle 1 has a sleeve 3 containing a tumbler lock 4 enclosed in a cylinder 5 which is capable of axial movement along the lock. The cylinder 5 is held in place by four lock tumblers in openings 11, and is guided axially by a tongue 8. When the key is inserted, the tumblers are withdrawn thus releasing cylinder 5 which moves axially under the action of spring 9, and tooth 14 engages tooth 13 on the spindle so that movement of the handle will actuate the lock spindle. If the handle is turned in the opposite direction to its usual opening movement, the cylinder 5 is raised by one tooth 13 riding over the other 14, until at the outmost point the tumblers of the lock 4 snap into the corresponding openings 11. The latch cannot be retracted again until the key is reinserted and the cylinder 5 released. A pin 7 and slot 6 are provided to locate the cylinder 5 relative to the lock 4. The slots 15 opposite to slots 11 are so arranged that the lock tumblers may enter them whatever the position of the cylinder 5 so as to allow of their displacement as the key is withdrawn. One of the tumblers may be made conical so that shortly before the extreme point of contact of teeth 13 and 14 is reached, it moves the cylinder 5 still further away from the spindle of the handle. If for any reason it is required to make the movement of the cylinder 5 more than the distance between the tumblers, the latter and their openings are given different cross sections or positions such that the outer tumblers may slide over the openings they must first pass.