Rotary cylinder lock flat key profile variation - involves extra rear side key groove and holed disc in cylinder slit

摘要

Lengthways ribs and/or grooves on the side provide variation in profile for flat keys for rotary cylinder locks. There is at least one additional lengthways groove in the rear of the key (13), acting in conjunction with a circular-section disc (21) in a cross slit (22) in the cylinder (11). The disc has a hole (25), running out from its edge (24), fitting the key rear profile. At the bottom (26) of the hole there is a protrusion (27), corresponding to the key rear groove. The rear side of the key may be slightly widened.