Patent GB-510179-A (GB)
Title: Improvements in and relating to locks and keys, also applicable to electric switches
IPC: B61L11/04
Filed: 1938-02-01
Abstract: 510,179. Latches and locks. WOLLASTON, H. J. BUCHANAN-. Feb. 1, 1938, Nos. 3055, 31529 and 33145. [Class 44] A lock mechanism comprises fixed and moving parts 8, 7 (Fig. 4) and two rows of tumblers 12, housed partly in the fixed part and partly in the moving part, the tumblers being arranged in a plane parallel to the line of movement of the part 7 so as to be movable in this plane at right-angles to this line of movement; the divisions between corresponding tumblers in the two rows are out of line in the locked position, as shown, but may be brought into line with one another and with the edge of the movable part, to allow movement of the latter, by means of a flexible key with a stepped end introduced through a guide 15. In the arrangement shown ir. Fig. 4, the tumblers are housed in common spaces in the two members 7, 8, but in a modification each tumbler may lie in a separate bore in one or each member; the member 7 serves as the bolt in the form shown, and is actuated by a slotted arm 21 on the door-knob spindle 120 engaging a pin 23 on the bolt. The tumblers are heavy enough to return to the locked position by gravity, but if the lock is to be used in a horizontal position return springs for the tumblers are provided in the bolt; these springs are arranged on guide pins, which enter bores in the tumblers, and similar guide pins for the tumblers may be provided on the fixed part of the lock. The key is of very thin flexible material, such as fibre, celluloid or metal strip, and the guide 15 fits it closely to prevent the insertion of any larger article. The guide, shown in side view in Fig. 17, has an enlarged opening for insertion of the key (which may have a rigid rear portion and be attached to a handle) and may have its back portion cut out at 49, except for parts near the sides, which serve to guide the key, so that the lock cannot be picked by inserting narrow feelers; a guide 57 or 57a is provided in this case to ensure that the fingers of the key enter the lock casing 8 properly. The lock may be placed on the inside of the door so that the key can be inserted vertically from that side, or a double guide may be required. The projecting portions of the key end are made slightly narrower. than the tumblers to ensure that they do not engage adjacent tumblers. Instead of being stepped, the end of the key may be curved, the lower ends of the tumblers being pointed. The key has side shoulders engaging the lock casing to limit its insertion, and these shoulders may be at different levels one side of the casing being suitably notched. The tumblers normally rest on the edge of the back plate of the key guide 15, and may be slotted to engage this edge. The abutting ends of the tumblers may be slightly rounded to allow for slight errors in the key. The invention may be applied to a rotary lock member, the tumblers being arranged in a plane perpendicular to the axis of rotation and their division lines being curved to correspond to the circumference of the rotary member. In order to prevent any of the tumblers from falling to their locked position before the bolt is fully shot in the arrangement shown in Fig. 4, a pick-up member 26 (see also Fig. 5) is provided which has a flange 27 which engages slots 25 in the upper tumblers and a groove 32 in the bolt when the bolt is withdrawn; the pick-up rocks about a flange on its upper end, and is pressed towards the tumblers by a spring 28 stretched across it or by a leaf spring. The tumblers are released when the bolt is nearly fully shot by a part of the bolt engaging a bevelled end of the pick-up to press the latter back. The bevel may be of such an angle, and the strength of the bolt return' spring 24 so chosen, that the tumblers will not be released if the bolt is allowed to come forward gently against the pick-up, so that the key is not required to permit the bolt to be released again, but if the bolt is withdrawn and then allowed to shoot forward (as when a door is slammed), or is moved forward positively by the knob, the pick-up is actuated and the bolt becomes locked. Alternatively, a pivoted hook 40 may be provided to be engaged with the pin 23 to prevent the bolt from moving to the locking position so that it acts as an ordinary door latch. The pick-up may engage with the lower instead of the upper tumblers, and is then preferably disengaged by a ramp on the pin 23; the grooves in the lower tumblers may be shallow and V-shaped. The pick-up means may be dispensed with, the key being used for any movement of the bolt; the fully withdrawn position of the bolt is chosen so that one or more tumblers will move to the locked position and a V-spring is preferably provided to ensure that the bolt is in one or other extreme position. The bolt-operating lever 21 has a square aperture engaging a square portion of' the knob spindle 120; in order to allow free action of the bolt when closing the door by pulling or pushing the appropriate knob, the spindle 120 is made slidable against a spring to bring a round portion into the aperture of the lever. The lock may be adapted to secure an electric switch in any of a number of positions by providing more upper tumblers than lower ones, so that each lower tumbler will have a complementary upper one in several positions of the movable member. The lock may be adapted for master key operation by dividing the lower tumblers and arranged for the master key to align these divisions with the edge of the movable member. Alternatively, the lower tumblers may have stepped ends, as shown in Fig. 15, arranged so that the master key 43 can engage the inner steps and the ordinary key the ends. The arrangement may be modified for use with a pivoted latch member by providing square holes 61, Fig. 18, in the member 7 and the casing to engage a squared part of the spindle 59 of the latch 60; in the locked position the apertures 61 are out of alignment, as shown, but when the member 7 is unlocked it can be moved to bring its aperture into line with the others to allow rotation of the spindle 59. This arrangement involves slight lateral movement of the spindle 59, which may be avoided by making the left-hand borders of the apertures 61 arcuate. The spindle may be turned to a small diameter at one part to prevent the lock being strained by force, and means are provided to prevent it from being pushed endwise through the lock. For double doors the member 60 may be a long cross-bar engaging under hooks on both doors; it may have a second arm operating an ordinary sliding bolt. According to the first Provisional Specification the tumblers are slightly tapered towards their abutting ends to avoid any one engaging two of the opposite ones; the lower tumblers may have tapered lower ends to avoid engaging the wrong step on the key. The tumblers may be of any cross-section, and may be tubular. The ' tumblers may be held in the unlocked position by a thumb-nut and clamping plate when it is required to use the bolt as an ordinary latch. The bolt may be used simply as a detent for the locking member of a drawer in order to allow gravity tumblers to be used. In locks for stepped keys, the sizes of the steps may be in multiples of a unit (e.g., a millimetre) and the keys may be made from a strip of material graduated one way in step units and the other way in units of tumbler width. Instead of shoulders being provided on the key, one or more of the tumblers may be in the correct unlocked position when pushed up as far as possible. The lock may be adapted for the insertion of the key from one side, the key having one side stepped and being moved laterally to unlock the mechanism. The key may engage shoulders or studs on the tumblers instead of the ends thereof. The second Provisional Specification describes a master key (also referred to in the first) comprising a number of separate strips slidably adjustable in a holder to reproduce the stepped shape required for any particular lock, the positions required for each lock being noted, or marked on the key. The ends of the tumblers may be grooved to ensure correct central engagement by the key. A hook similar to the hook 40 in Fig. 5, but engaging the pin 23 from beneath, may be provided to hold the bolt out of the locking position for one operation only, for example to allow closing of the door after opening with the key. In the case of a bolt without a return spring, it may be arranged that the sets of tumblers are moved entirely clear of one another in the unlocked position so that the bolt may be shot by a rapid move - ment without requiring the use of the key. According to the third Provisional Specification, the lock having additional upper tumblers may be used in conjunction with an ordinary spring latch, being arranged to withdraw the latch in the last part of its own retraction movement but being lockable in an intermediate position in which the bolt is withdrawn but the latch is engaged and can only be withdrawn from inside. In the arrangement shown in Fig. 5 a key rotatable on a pin inside the door may be provided to unlock the door from the inside. The pick-up may be connected to the bolt instead of the lock casing, and may engage the lower ends of the upper tumblers instead of grooves in these. The tumblers may be weighted or made of heavy metal. A sliding bolt or latch or a lifting latch may be locked by a bolt sliding across behind or above the latch, this bolt passing through a circular hole in the lock member 7, which engages an annular groove in the bolt in the locked position; a key of the ordinary type may be locked in a slightly withdrawn position, in which it cannot be turned, in a similar manner.