Key hole fitting in door lock plate - has hole non vertically aligned, for secure key retention

摘要

The protective metalwork is for locks on doors. There is a special arrangement of the opening for insertion of a key to operate the lock component. This opening (9a) in the long plate or protective plate (9), and in the lock component (6)- or only in one of the two latter-is formed at an angle deviating conspicuously from the vertical. It can be in any position but pref. lying horizontally, at 90 deg. to the usual keyhole angle. After being passed through the first aperture (9a) the key must be turned before it will pass through the second aperture (7). Simple structural measures ensure that there is no danger of the key falling out of the plate when the door is banged, nor of it being easily pushed out from the other side.