Anti-theft device having a cylinder lock

Claim 1

An anti-theft device comprising a lock body, a cylindrical barrel rotatably mounted in said body and including an axial passage for insertion of a key, locking means in said barrel engaging said body to prevent rotation of said barrel, said locking means being operable by insertion of a correctly coded key to free the barrel for rotation within the body, said barrel being axially slidable within said body between an outer, locked position and inner, operative position, closure means disposed at an entrance end of said axial passage and movable between a first position in which said means is effective to prevent insertion of a key into said passage in said outer position of said barrel and second position to allow insertion of the key into said passage in the inner, operative position of said barrel, and means biasing said closure means towards said first position, pressure applied to said closure means against the action of said biasing means by the leading end of the key, moving said barrel to said operative position and thereafter moving said closure means to said second position to allow insertion of said key into said passage, said barrel including an operating part rotatable therewith and cooperating with a bolt element to move that element between locking and releasing positions, said barrel being formed at that end thereof from which a key is inserted therein, with a T-sectioned slot, said closure means being guided for axial radial movement therein, a thrust ring disposed between opposed surfaces of said body and barrel and rotatable with said barrel, said ring including elements projecting into said slot and cooperating with said closure means, means biasing said barrel towards said outer position, and wherein a cap is rotatably mounted at that end of the barrel from which said key is inserted and between the thrust ring and a ring protecting said body, said cap being coupled to rotate with the barrel by lugs positively engaged in the T-shaped groove, said lugs being radially and axially contiguous with free ends of said parts of the thrust ring.