Theft prevention system for vehicle number plate - uses locking components behind plate for screws with concealed heads

摘要

The anti-theft system for a vehicle number plate (1) uses nuts and bolts with the heads (8) of the nuts concealed. The number plate is mounted on a stainless steel plate (2) with its edges flanged over (3a) to grip the number plate. This backing plate incorporates recesses (5) which retain the screw heads behind the number plate. Each screw passes through the sheeting of the vehicle (6) and a locking disc (11), being square in section over this region. The remainder is threaded for a lock nut (7). The nut has a toothed inner face which locks against the toothed surface of the locking disc. The proportions of the teeth are specified, the nut being of hardened steel, the screw head diameter being at least 20 mm and the thickness of the backing plate being about 1mm. The locking disc is of spring steel.