Drag chain

Claim 1

A chain comprising a plurality of longitudinally aligned Ushaped links each including a transverse cross bar having a bore therethrough and a pair of side arms extending substantially longitudinally of the chain from opposite ends of the cross bar, a keeper head at the free end of each said side arm, an outside bearing face at each end of said cross bar, the opposed surfaces of said keeper heads each provided with an inside bearing face, the spacing therebetween permitting straddling of said outside bearing faces of the next adjacent link cross arm, each said keeper head including a pocket communicating with an elongated opening through said inside bearing face on the one hand and an access opening through the outer side of said side arm on the other hand, each said pocket defined by a front wall on the forward portion of each said keeper head and an end wall extending rearwardly from the outermost edge of each said front wall, each said access opening defined by a rearwardly facing edge on said end wall and an inwardly offset and forwardly facing edge on said side arm, said offset relationship providing a forwardly facing approach to said pocket through said access opening the axis of said approach which when extended is disposed substantially laterally away from each said link side arm and said cross bar, the longitudinal distance between said pair of edges of both said side arms being no less than the diameter of said pin shank, and a lock pin insertable first through one of said access openings thence through the bore of a next adjacent link and finally into the pocket of the opposite said keeper head through the elongated opening thereof, said lock pin including a cylindrical shank having a forward curved surface of a length sufficient to extend from within one said pocket to a point within the other said pocket of each said link, whereby subsequent longitudinal displacement of the two links joined by said lock pin moves said lock pin forwardly through said elongated openings to entrap both ends of said lock pin within said keeper head pockets to preclude axial displacement of said lock pin as said end walls mask the two ends of said pin and said forward curved surface of said lock pin engages the interior of both said keeper head front walls, and an offset head radially projecting from one distal portion of said lock pin shank.