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 agricultural equipment.

Agriculture and horse-drawn vehicles

Agricultural equipment is hauled by a tractor-mounted drawbar. Specialist agricultural tools such as

plough A plough or ( US) plow (both pronounced ) is a farm tool for loosening or turning the soil before sowing seed or planting. Ploughs were traditionally drawn by oxen and horses but modern ploughs are drawn by tractors. A plough may have a wooden ...

s 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 A wagon (or waggon) is a heavy four-wheeled vehicle pulled by Working animal#Draft animals, draft animals or on occasion by humans, used for transporting goods, commodities, agricultural materials, supplies and sometimes people. Wagons are i ...

, cart,

chariot A chariot is a type of vehicle similar to a cart, driven by a charioteer, usually using horses to provide rapid Propulsion, motive power. The oldest known chariots have been found in burials of the Sintashta culture in modern-day Chelyabinsk O ...

or other

horse-drawn vehicle A horse-drawn vehicle is a piece of equipment pulled by one or more horses. These vehicles typically have two or four wheels and were used to carry passengers or a load. They were once common worldwide, but they have mostly been replaced by auto ...

s to between the

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 mi ...

s. A steel drawbar attaches a three-point hitch or other farm implement to a

tractor A tractor is an engineering vehicle specifically designed to deliver a high tractive effort (or torque) at slow speeds, for the purposes of hauling a Trailer (vehicle), trailer or machinery such as that used in agriculture, mining or constructio ...

Road

A drawbar is a towing or pushing connection between a tractive vehicle and its load.

Light vehicles

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.

Heavy vehicles

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). By contrast, the fifth wheel is designed to transmit a proportion of the load's weight to the hauling vehicle. Drawbar configuration is mostly seen on hydraulic modular trailer and ballast tractor combination to haul oversize loads which require special trailer and tractor.

Drawbar eye

A drawbar eye, also called tow eye, is a mechanical part to connect an independent trailer/ dolly via a drawbar coupling to a

. They are made from high tension material to bear heavy loads while being pulled by the tractor. The eye is made in the shape of an "i" with a hole at top which is locked in the drawbar coupling and the lower part is mounted to the drawbar making it an essential connector between the drawbar and drawbar coupling. The drawbar eye is used in many heavy transport operations around the world. It is mostly used for

agriculture Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created ...

equipment,

construction Construction are processes involved in delivering buildings, infrastructure, industrial facilities, and associated activities through to the end of their life. It typically starts with planning, financing, and design that continues until the a ...

equipment, road trains, dolly trailers, full trailer and hydraulic modular trailers.

Rail

Two or more

passenger A passenger is a person who travels in a vehicle, but does not bear any responsibility for the tasks required for that vehicle to arrive at its destination or otherwise operate the vehicle, and is not a steward. The vehicles may be bicycles, ...

or freight cars may be attached by means of a drawbar rather than a coupler. At each end of the permanently coupled vehicles there is a regular coupler, such as the North American Janney coupler or the Russian SA3 coupler. The use of a drawbar eliminates slack action.

Rail applications

* MR-90 * MR-63 * MR-73 * MPM-10 * Drawgear

References

External links

* * * {{Railway coupling Agricultural machinery Couplers Trucks Transport operations Articulated vehicles Heavy equipment