Patent GB-443180-A (GB)
Title: Combination lock
IPC: E05B37/04
Filed: 1935-03-07
Abstract: 443,180. Permutation locks. BERGGREN, H. E., 6, Bõltgatan, Stockholm. March 7, 1935, No. 7169. Convention date, March 7, 1934. [Class 44] A permutation lock has a series of tumblers which are successively actuated by a member having two movements, one of which is automatic, so that a single unidirectional movement imparted manually to the member serves to actuate a tumbler and to initiate the setting of the member in position for actuating the next tumbler. A tail-piece 12 of a latch 13 slides between projections 15, on the cover plate of the lock, which also guide a plate 14 arranged between the tail-piece 12 and the cover plate. A projection 18 on the plate 14 projects across the lock and prevents withdrawal of the bolt from the outside by engaging the ends of tumblers 26 pivoted on a pin 16, slots 58 in the tumblers enabling the plate 14 to be moved when the lock is set to the correct combination. The tumblers are separated by washers 28 and each has a toothed end 29 co-operating with a pawl 31, these pawls being mounted on a second pin 30 and separated by washers 32. The tail-piece 12 has a slot 19 to enable it to move inwards relative to the plate 14 against a spring 20 either automatically when the door is shut or manually by means of a knob 21 having a flat shank working in a slot 22 in the cover plate. The slot 22 has a circular enlargement at each end so that by turning the knob 21 through 90‹ the latch can be locked in its shot or withdrawn positions. For actuating the tumblers, a helical cam 37, which can turn and slide on a pillar 35 extending through the door, is secured to a tube 39 having a sleeve 40 at its forward end also turning and sliding upon the pillar 35. A spring 51 connected to the pillar 35 and tube 39 tends to turn the tube 39 clockwise, as viewed from outside the door, and also to move it axially towards the cover plate of the lock. The tube 39 and sleeve 40 carry a pin 50 extending through a slot 49 in a sleeve 48 having a circular flange 45 fitted with finger holes 46 similar to those of an automatic telephone dial, the sleeve being held in position between a shoulder 47 on the pillar 35 and a fixed flange 41 bearing a series of numbers and a finger stop 42. The flange 41 is secured by a bolt 43 extending right through the lock. A spring detent 53 extending the full depth of the bank of tumblers holds the cam 57 in its initial position, prior to the actuation of each tumbler, by engaging the radial edge 37<1>, and an offset flange 52 engages the face of the tumbler as shown. To set the combination the flange 45 is turned counterclockwise by inserting a finger in the appropriate hole and moving it up to the finger stop 42. By the time the flange 52 is clear of the first tumbler the cam 37 can rest against the face of the next one, and as the cam is only slightly less in thickness than one tumbler plus one washer, continued movement causes the edge of the cam to raise the first tumbler which is held in its set position by its pawl 31. The spring 51 then returns the cam to its initial angular position and as its smallest diameter clears the face of the next tumbler the cam and tube 39 move inwards axially until the flange 52 engages the face of the next tumbler. When all the tumblers have been set, the radial edge 37<1> of the cam engages behind a projection 54 on the plate 14 and by turning the flange 45 clockwise the plate 14 and latch 13 can be moved to open the door. The slot 19 has an enlargement 191 to clear the projection 54 when acting as a latch. To reset the tumblers the cam is drawn forwards by means of the pin 50 until its edge 371 engages a corner of a plate 55, Fig. 4, set in front of the tumblers and guided by the pin 16 and a pin 56. This plate has a bent prong 57 extending across the lock to engage the tops of the pawls 31 so that a sliding movement of the plate 55 effected by the cam 37 releases all the pawls and the tumblers drop to their initial position. Since the projection 18 is always out of contact with the tumblers until after the last tumbler has been set the lock cannot be picked by feeling.