Heavy Haulage drawbar hitch on a ballast tractor unit
English Dictionary definition[]
Noun[]
Drawbar (haulage) ({{{1}}})
- (rail transport) An open-mouthed bar at the end of a car, which receives a coupling link and pin by which the car is drawn. It is usually provided with a spring to give elasticity to the connection between the cars of a train.
- (rail transport) A bar of iron with an eye at each end, or a heavy link, for coupling a locomotive to a tender or car.
- (road transport) A device to couple a powered road vehicle to a load to transfer tractive effort to the load, either as a push or as a pull.
- A device invented originally by Hammond for installation in its organs
A device for changing the tools on milling machines
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This article is about haulage. For other uses, see Drawbar (disambiguation).
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.
Agriculture[]
This section requires expansion. Agricultural equipment is hauled from a tractor mounted drawbar. Specialist agricultural tools such as ploughs are attached to specialist drawbars which have functions in addition to transmitting tractive force.
Road[]
Ballast tractor unit pulling a 150 ton capacity modular trailer via a drawbar
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, where a load of up to ~50 kg is part of correct trailer loading practice), 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). By contrast, the fifth wheel is designed to transmit a major proportion of the load's weight to the hauling vehicle.
A drawbar is mounted or located on the tractive vehicle and is used to accept the coupling of the load. The direction of haulage may be push or pull, though pushing tends to be for a pair of ballast tractors working one pulling and the other pushing an exceptional load on a specialist trailer.
Rail[]
- Main article: Coupling (railway)
A rail locomotive hauls its load through a drawbar and hauling force is transmitted between rolling stock via drawbars between units. With rail transport the tractive effort is "cascaded" through the train of wagons. Each wagon, even though unpowered, may be considered the tractive vehicle for the wagon(s) further away in the chain.
See also[]
References[]
- Drawbar (haulage) in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913 - Wiktitionary
- US 6739402 Transport drawbar
- US 5096075 Slackless drawbar assembly with gravity responsive wedge (rail application)
- US 5598937 Slackless drawbar assembly (rail application)
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