Security device for trailer coupling pin

Claim 1

A security device adapted for locking engagement over the coupling pin of the trailer of a tractor-trailer rig comprising: a truncated conical housing having a solid base at its tapered end; a sleeve secured to the inside surface of said base and extending therefrom for substantially the height of said housing, said sleeve having an inside diameter larger than the outside diameter of the coupling pin to be covered to provide a sliding fit between the sleeve and the coupling pin, said sleeve having a pair of opposed horizontal slots intermediate its length; a pair of jaw elements adapted to fit within said slots and providing opposed locking surfaces on their lower faces when fully inserted into said slots, said jaw elements having upper cam surfaces for engaging the coupling pin as it is inserted into said sleeve for camming the jaw elements outwardly during such insertion; means for biasing said jaw elements into said slots comprising pivotally mounted jaw carriers substantially surrounding said sleeve and secured to said jaw elements and resilient means for urging said jaw carriers inwardly; a lock recessed in the sidewall of said housing and having rotatable cam elements operable to engage mating surfaces on said jaw carriers to urge said jaw carriers outwardly against the bias of said resilient means; and a cover plate detachably secured to the larger end of said conical housing and having a central opening for passing the coupling pin.