Patent ID: 8272654

Claim:
A bolt assembly for locking longitudinally extending members of a frame of a transport semi-trailer together with a trailer body movably arranged on the longitudinally extending members, each of the longitudinally extending members being provided with a locating hole, wherein: the bolt assembly comprises a bolt, an inner spring, a sliding sleeve, an outer spring and a bracket; the bolt comprises a thick axle portion and a thin axle portion; a step is formed at a position where the thick axle portion and the thin axle portion are joined, and a pin end-plate is fixed at a free end of the thin axle portion; the inner spring is put on the thin axle portion of the bolt; the thin axle portion and the inner spring are accommodated in the sliding sleeve, and an end of the sliding sleeve is provided with a sliding sleeve end-plate which abuts against the step; the outer spring is put on an outer circumference surface of the sliding sleeve; the sliding sleeve and the outer spring are accommodated in the bracket; two ends of the inner spring abut against the pin end-plate and the sliding sleeve end-plate, respectively; and two ends of the outer spring abut against the bracket and the sliding sleeve end-plate, respectively; the bracket is fixed on the trailer body; the sliding sleeve is pulled such that the sliding sleeve end-plate compresses the inner and outer springs to force the bolt to be pulled out from the locating hole under an action of an elastic force of the inner spring, and after the sliding sleeve is released, the bolt is inserted into the locating hole under the action the elastic force of the outer spring.