KEY HOLE PROTECTIVE DEVICE Russian patent published in 1999 - IPC

FIELD: hardware, in particular, construction of top secrecy locks. SUBSTANCE: device has rotary washer positioned in lock body and provided with key opening arranged concentrically to washer axis. Upon rotation of washer, key opening may be aligned with key hole and key opening in outer surface of lock body. Both key openings are shaped in accordance with key hole. Opening in lock body is positioned in symmetry with key hole with respect to plane extending through washer axis and has arced slot joined with opening. One end of slot coincides with key rod receiving portion of opening and other end coincides with key rod receiving opening. Slot curvature radius corresponds to eccentricity radius of opening in washer. EFFECT: simplified construction, provision for using the device for different widely used locks having one or two drifts. 3 cl, 2 dwg