Drawbar (haulage)

A drawbar is a solid coupling between a hauling vehicle and its hauled load. Drawbars are in common use with rail transport, road trailers, both large and small, industrial and recreational, and with agricultural equipment. Agricultural equipment is hauled by a tractor-mounted drawbar. Specialist agricultural tools such as ploughs are attached to specialist drawbars which have functions in addition to transmitting tractive force. This was partly made redundant with Ferguson's development of the three-point linkage in his famous TE20. A wooden drawbar extends from the front of a wagon, cart, chariot or other horse-drawn vehicles to between the horses. A steel drawbar attaches a three-point hitch or other farm implement to a tractor. A drawbar is a towing or pushing connection between a tractive vehicle and its load. On light vehicles, the most common coupling is an A-frame drawbar coupled to a 1 7/8 inch or 50 mm tow ball. These drawbars transmit around 10% of the gross trailer weight through the coupling. The direction of haulage may be push or pull, though pushing tends to be for a pair of ballast tractors working together, one pulling and the other pushing an exceptional load on a specialist trailer. The most common drawbar configuration for heavy vehicles is an A-frame drawbar at the front of a full trailer that connects to a tow coupling on a hauling vehicle On heavy vehicles, the drawbar is coupled using a drawbar eye, typically of 40 mm or 50 mm diameter, connected to a bolt and pin coupling. Commonly seen brands include Ringfeder, V. Orlandi and Jost Rockinger. These drawbars transmit little or no downwards force through the coupling. The drawbar should not be confused with the fifth wheel coupling. The drawbar requires a trailer which either loads the drawbar lightly (for example a small boat trailer, or caravan, or the load is the weight of the coupling components only (larger trailers, usually but not always with a steerable hauled axle, front or rear).