GB1120833A - Improvements relating to combination locks - Google Patents

Abstract

1,120,833. Combination I o c k s . SEAL SAFE CO. Ltd. 19 July, 1965 [17 April, 1964; 25 Aug., 1964], Nos. 16113/64 and 34834/64. Heading E2A. A combination lock comprises a slidable plate 16 for location in a position where it obstructs a keyhole to be safeguarded and having a projection 17 thereon, a series of coaxial rotatable wheels 13, 14, each having one or more notches 13b or 14b in its periphery and the wheels being rotatable to positions wherein the, or one of the, notches of each lies opposite the projection on the said plate, means for indexing the rotation of said wheels so that various angular positions of the notches can be determined and means for displacing said plate when the projection and the notches are in mutual register. The lock shown has a body part 11 adapted to be fixed to a door over its keyhole to prevent access to the keyhole and the body part 11 has a boss 12 extending outwardly and axially thereof on which is rotatably mounted the inner index wheel 13; rotatably mounted on the wheel 13 is the outer index wheel 14. Each wheel has an index plate 13a, 14a, disposed within the body part and the plates contain the notches 13b, 14b in the peripheries thereof. The outer index wheel is axially located on the inner wheel between a shoulder 13c and the outer periphery of the inner wheel and the index plate 13a and both wheels are axially positioned by the engagement of a radially inwardly directed flange 11a on the body part with a channel in the periphery of the outer index wheel which is between the index plate 14a and the flange 14c formed integrally with the wheel. Guided in the slot 12a in the base of the boss is the slidable plate 16 which is retained in place in the slot by a base plate 21 secured to the rear base of the body part. The plate 16 is formed with the keyhole slot 18 and the plate is normally biased by a spring 23 so that the keyhole slot 18 is out of alignment with a keyhole slot 21a in the base plate 21 and a keyhole slot 15 in the boss. The slots 15 and 21 a are normally in alignment with the keyhole in the door and when the plate 16 is moved so that its slot 18 is in alignment with the slots 15 and 21a, a key can be inserted into the keyhole in the door. Movement of the plate 16 is normally prevented by the projection 17 on the plate which only allows sliding of the plate when the notches in the index wheels are in alignment with it. The plate 16 is moved by the tip of the key engaging the surface of a ramp 19a, secured to the plate. The index plates are indexed by spring loaded detent members which engage shallow recesses 13d, 14d around the periphery of each plate. In a modification more than one notch for the projection 17 can be provided in each index plate. In a further modification instead of the key being used to move the plate 16, a push button is provided located centrally of the boss 12 and the keyholes 15, 18 and 21A are offset; this arrangement allows the combination lock to be used if the door keyhole is near the edge of the door.