Schraubbefestigung fuer Kraftfahrzeugraeder

摘要

This thief-proof device comprises a lockable protective cover surrounding a securing element This screw device has reduced overall dimensions, is easy to manufacture and is very reliable as a security and securing element. A plurality of annular grooves (4) are provided in the hexagonal head of the securing element which cooperate with a retaining ring (5) arranged in the inside of the cylindrical surface of the protective cover (3). The protective cover comprises an axial pin (7) cooperating with the retaining rings (5), and between these rings are arranged spacing rings (20). The retaining rings (5) have a centre (8) upset with respect to the axes (9) of the securing element and have an inner diameter which is equal or bigger than the diameter or the circle circumscribed to the hexagonal head. A first branch (12) of each ring extends from the pin (7) to a stop surface (13) which may have various shapes and against which bears a key when introduced in a slot (22) arranged diametrically facing the pin (7) and made in the peripheral part of the protective cover. A second branch (15) of each ring is longer than one of the six flats of the hexagonal head and may be inserted into the corresponding groove (4). A spring (17) bears against the innercylindrical surface (10) of the cover (3) and exercises a force on the first branch (12), which forces it into the corresponding groove (4).