Patent GB-328681-A (GB)
Title: Improvements in or relating to combination locks
IPC: E05B37/16
Filed: 1929-02-04
Abstract: 328,681. Bishop, F. C. Feb. 4, 1929. Locks, permutation.-A lock of the kind having a number of bolts selectively operative and released only by correct selective operation of corresponding press buttons comprises bolts 6 carried by one part of the lock and urged towards shot position by springs 22. When shot, bolts 6 enter apertures in the other part of the lock housing positively operable bolts 2. Bolts 2 are of equal lengths and each is screwed into a slidably mounted nut 3. Bolts 2 axe urged towards the left by the corresponding bolts 6, so as normally to hold the nuts in alignment against an apertured plate 1. The extent to which each bolt 2 is screwed into its nut 3 determines whether, and to what extent, the corresponding bolt 6 can effect locking engagement. As shown bolt 2<a> is screwed in to full permissible extent, its inner end 4<a> projecting through plate 1, allowing full engagement of corresponding bolt 6, and bolt 2b is screwed in to half the extent allowing correspondingly limited engagement by its bolt 6. The remaining bolts are adjusted so that the meeting nuts are flush with the meeting faces 7 of the two parts of the lock. To release the lock, plate 1 is moved to the right to full extent, thus moving all the nuts 3 and bolts 2. This brings the outer end of bolt 2a flush with faces 7 and causes the remaining bolts 2 to push in their bolts 6 and make locking engagement with the recesses in the right-hand part of the lock. At the same time the nuts are brought under a series of corresponding push-buttons, not shown. The inner end of each button, when operated, is adapted to engage one or other of two recesses 8, 8<a> in the corresponding nut 3 and so retain its bolt 2 against return when plate 1 is returned to the left. In this position the button corresponding with bolt 2<a> is operated to enter recess 8 and retain the bolt 2<a> in released position. Plate 1 is then returned half-way, thus bringing bolt 2<b> to release position, where it is retained by operating its push-button to enter recess 8<a>. Plate 1 is then completely returned, allowing the remaining bolts to return to unlocked position. If, when plate 1 is displaced to the right, a wrong push-button is operated, the corresponding bolt 2 is retained in locking engagement with the right-hand part of the lock. Operation of plate 1 is effected by a cam on a knob-operated shaft rotatable to predetermined positions in which it is retained by ratchet-shaped projections on a spring-pressed plate engaged by a pin on the shaft, to leave both hands of the operator free. Release is effected by a press-button which depresses the plate clear of the pin. To enable the lock to be released when desired without operation of the push-buttons, a latch plate 12 is provided normally urged to the left by a spring 15 and movable to the right by a handle, not shown. When moved, the plate acts on the ends 4<a>, 4<b> of the operative bolts to move them to unlocked position, but leaves the remaining bolts in the released position shown. This device may be rendered inoperative when desired by means of a screw, not shown, accessible only when the lock has been released, adapted to project into engagement with plate 12 and prevent its movement. Each bolt 2 is provided near its end with a groove 31 adapted to be engaged by a spring- catch, not shown, to retain the bolt with its end flush with face 7 when the lock is open. This prevents detection of the bolts to be selectively operated by pressing on the exposed ends of the bolts. The catches are automatically released when the two parts of the lock are brought together on closing the door &c. to which the lock is applied. The Specification describes in detail the arrangement and operation of the catches, and the use of a strip of paper pasted over the catches and visible through an inspection window to show when any catch has been tampered with. A latch plate 16 urged to the left by a spring 24 has an extension 17 with bevelled nose 20 adapted to engage a projection (not shown) as the door &c. is being opened and move plate 16 to the right. The plate engages cotter pins 23 or caps on the inner ends of spring-bolts 6 and retains them in unlocked position by a spring-catch, not shown, engaging an aperture 21 in extension 17. This catch is automatically released on closing the door &c. Specification 293,607 is referred to.