Abstract: A pintle hook type tractor-trailer coupling component for heavy duty use. Multiple detent and safety hook means are provided for maintaining it securely, but releasably, in its operative position, coupled to the eye component of a pulling truck or tractor. Automatic take-up means assure a snug fit between the hook and the eye, irrespective of wear.

Abstract: In a trailer train combination having a tractor, lead trailer and one or two more following trailers, an adjustable dolly under the front end of each following trailer provides for close coupling of the multiple trailers in end to end contact. Then the multiple trailers are lifted to inclined position causing the upper trailer or trailers to discharge its flowable contents out through the lower trailer in a self unloading operation. The dolly has a slidable fifth wheel assembly and self steering ground wheels which may be locked in straight forward positions. A cab controlled electric and pneumatic control system controls these and other functions in the dolly. The trailers may be equipped with walking floors for self unloading in level positions.

Abstract: In a trailer train combination having a tractor, lead trailer and one or two more following trailers, an adjustable dolly under the front end of each following trailer provides for close coupling of the multiple trailers in end to end contact. Then the multiple trailers are lifted to inclined position causing the upper trailer or trailers to discharge its flowable contents out through the lower trailer in a self unloading operation. The dolly has a slidable fifth wheel assembly and self steering ground wheels which may be locked in straight forward positions. A cab controlled electric and pneumatic control system controls these and other functions in the dolly. The trailers may be equipped with walking floors for self unloading in level positions.