Abstract: A device for assembling the upper ends of the lateral uprights of a transport or handling cart with the transverse tubular grip handle, with comprises a sheath fitting on the bent upper end of each upright and a lock key adapted to be inserted into the sheath cavity so as to interlock the sheath and the upright end. Each sheath has formed on its inner side a projecting stud engageable into the corresponding end of the tubular grip handle. A cam projecting from one or both sides of the lock key engages a registering aperture formed in the sheath walls, one of these members, key or sheath, having a certain elasticity to permit the insertion of the key into the sheath.