METHOD FOR PROTECTION OF LEVER LOCK WITH PROTECTIVE BUSHING AGAINST UNAUTHORISED OPENING AND LEVER LOCK FOR ITS REALISATION Russian patent published in 2013 - IPC E05B15/00 

FIELD: construction.

SUBSTANCE: in process of the first half-turn a protective bushing 9 interacts with a key, turns and closes the space of the key hole (see dwg. 3 and dwg. 6). Only the space in the centre of the key hole providing for guaranteed operation of a key in the lock remains uncovered. Simultaneously with the turn the protective bushing 9 interacts with its cut 10 with an adjacent spring-loaded plate 12, raising it into the upper position. Raising to the upper position happens in process of transition from a cut plane 10 to a circumferential surface of the protective bushing 9. The spring-loaded plate 12 in process of crossbar 4 plate movement is fixed on the ledge 5 and remains in the upper position until the last half-turn is made. In process of raising of the plate 12, it synchronously interacts via a bend 14 with a plate 16, which covers a key hole - excluding a hole providing for guaranteed operation of the key in the lock (see dwg. 2-8). When raising to the upper position, the plate 16 remains in the upper position until the last half-turn is made. The key hole remains continuously covered with the plate 16, at least in positions of the key 45-315° (in locks with one full rotation of the key - 360°) and 45-675° (in locks with two full rotations of the key 720°).

EFFECT: guaranteed protection against most master keys currently existing.

4 cl, 8 dwg