Rawcliffe Ballast Tractor & Trannsformer

A drawbar is a solid

coupling A coupling is a device used to connect two shafts together at their ends for the purpose of transmitting power. The primary purpose of couplings is to join two pieces of rotating equipment while permitting some degree of misalignment or end mov ...

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 and horse-drawn vehicles

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

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

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 3 point linkage in his famous TE20. A wooden ''drawbar'' extends from the front of a wagon,

cart A cart or dray (Australia and New Zealand) is a vehicle designed for transport, using two wheels and normally pulled by one or a pair of draught animals. A handcart is pulled or pushed by one or more people. It is different from the flatbed tr ...

chariot A chariot is a type of cart driven by a charioteer, usually using horses to provide rapid motive power. The oldest known chariots have been found in burials of the Sintashta culture in modern-day Chelyabinsk Oblast, Russia, dated to c. 2000&nb ...

or other

horse-drawn vehicle A horse-drawn vehicle is a mechanized piece of equipment pulled by one horse or by a team of horses. These vehicles typically had two or four wheels and were used to carry passengers and/or a load. They were once common worldwide, but they have m ...

s to between the

horse The horse (''Equus ferus caballus'') is a Domestication, domesticated, odd-toed ungulate, one-toed, ungulate, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two Extant taxon, extant subspecies of wild horse, ''Equus fer ...

s. A steel ''drawbar'' attaches a

three-point hitch The three-point hitch (British English: three-point linkage) is a widely used type of hitch for attaching ploughs and other implements to an agricultural or industrial tractor. The three points resemble either a triangle, or the letter A. Three-p ...

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 or machinery such as that used in agriculture, mining or construction. Most common ...

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, 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 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 an ...

, 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 Fifth is the ordinal form of the number five. Fifth or The Fifth may refer to: * Fifth Amendment to the United States Constitution, as in the expression "pleading the Fifth" * Fifth column, a political term * Fifth disease, a contagious rash th ...

. The drawbar requires a trailer which either loads the drawbar lightly (for example a small

boat trailer A boat trailer is designed to launch, retrieve, carry and sometimes store boats. Commercial boat trailers Commercial hydraulic boat trailers are used by marinas, boat yards, boat haulers, boat dealers and boat builders. Generally this type of ...

, 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 Hydraulics (from Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counter ...

and ballast tractor combination to haul

oversize load In road transport, an oversize load (or overweight load) is a load that exceeds the standard or ordinary legal size and/or weight limits for a truck to convey on a specified portion of road, highway, or other transport infrastructure, such as a ...

s 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

. the eye is connected to the front end of a drawbar with bolt, flange-mounting or welding. Most 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 or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to ...

equipment, construction equipment,

road train A road train, land train or long combination vehicle (LCV) is a trucking vehicle used to move road freight more efficiently than semi-trailer trucks. It consists of two or more trailers or semi-trailers hauled by a prime mover. History Early ...

s, dolly trailers, full trailer and hydraulic modular trailers.

Rail

Two or more

passenger A passenger (also abbreviated as pax) 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. Th ...

freight car A railroad car, railcar ( American and Canadian English), railway wagon, railway carriage, railway truck, railwagon, railcarriage or railtruck (British English and UIC), also called a train car, train wagon, train carriage or train truck, is ...

s may be attached by means of a drawbar. At both extremes there is a regular coupler such as the North American

Janney coupler Janney couplers are a semi-automatic form of railway coupling that allow rail cars and locomotives to be securely linked together without rail workers having to get between the vehicles. They are also known as American, AAR, APT, ARA, MCB, knuckl ...

or the Russian

SA3 coupler SA3 couplers (also known as СА3 or СА-3 couplers per the typical foundry stamp on top of these couplers, meaning "Советская Автосцепка, 3" in Russian or "Soviet Auto-latch 3" in English) or Willison coupler and Russia ...

. This drawbar eliminates

slack action In railroading, slack action is the amount of free movement of one car before it transmits its motion to an adjoining coupled car. This free movement results from the fact that in railroad practice cars are loosely coupled, and the coupling is oft ...

Rail applications

MR-90 The MR-90 was a class of single-level electric multiple unit (EMU) railcars built in 1994-1995 by Bombardier Transportation for the Société de Transport de la Communauté Urbaine de Montreal (STCUM) and now operated by Exo. These cars were ord ...

MR-63 The MR-63 (''M''atériel ''r''oulant 19''63'') was the first generation of rubber-tyred rolling stock of the Montreal Metro in the city of Montreal, Quebec, Canada. Based on the MP 59 of the Paris Métro in France, the trains were in use on thr ...

MR-73 The MR-73 (''M''atériel ''r''oulant conçu en 19''73'') is the second generation of rubber-tired rolling stock used on the Montreal Metro. Since the retirement of the first generation MR-63s, the MR-73 trains are in use on three of Montreal's fo ...

MPM-10 The MPM-10 (Montréal Pneumatic Material 2010), commonly known as the Azur, is the third and newest generation of rubber-tired rolling stock used on the Montreal Metro in Canada, built by a consortium of Bombardier Transportation and Alstom. The ...

* Drawgear

References

External links

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