Ballast tractor
Encyclopedia
A ballast tractor is a heavy haulage
road vehicle designed to pull or push heavy or exceptionally large loads. Unlike the tractor unit from an articulated trailer
, the ballast tractor is designed or adapted to pull or push loads from a drawbar
. By contrast an articulated tractor unit pulls from a "fifth wheel"
, and only pushes when reversing its load.
The name ballast is derived from the nautical term (see sailing ballast
) describing heavy material added to a vessel to improve stability. For a ballast tractor, ballast is added over the driving wheels to increase the available tractive effort
. The additional weight increases the friction between the tyres and the road surface. Without such ballast, the tractor would be unable to overcome the inertia and friction of rolling of a heavy trailed load, and its wheels would rotate without generating forward motion (termed wheelspin
). With a semi-trailer, the weight of the trailer presses down through the fifth wheel and adds ballast. In the case of a ballast tractor, the load is supported separately and its weight provides no ballast: the drawbar only transmits a horizontal force to the load.
High inertia
is encountered when starting to move a heavy load. To overcome this, ballast tractors tend to have high power engines and engines that provide lots of torque
, especially at low speeds. Ballast tractors are often fitted with heavy duty hub reduction axle
s, or high reductive gear boxes to increase torque at the wheel, therefore heavy duty ballast tractors tend to have low maximum speeds.
A strong chassis
is required, to support the extra weight of the ballast and the pulling forces imposed by the drawbar. A reinforced chassis allows multiple tractors to be coupled together to increase the total power and traction available. Heavy-duty versions of commercial tractor units may be fitted with a ballast box and suitable drawgear, alternatively, a ballast tractor may be purpose-built for the role. The ballast is located above the driving axle, and tractors often have multiple driving axles to reduce the axle load, with the ballast distributed to avoid overloading a particular axle.
A ballast tractor that is built as a ballast tractor tends to be the heaviest class of on-highway trucks. In some cases, the weight of the chassis alone of these trucks (the kerb weight) can be even greater than their axle configuration legal Gross Vehicle Weight
(GVW) permits, so require special permission to use the roads.
Another specialized use for ballast tractors is in showman vehicles. The ballast tractor used in this case may be a typical tractor unit fitted with a ballast box used to tow one or more specialized trailers that contain fairground rides which may not fit onto a standard fifth wheel connecting trailer. The overall weight of showman's vehicles tends to be much less than those used for heavy haulage to comply with vehicle weight legislation, particularly axle loads. Sometimes, one or more generator sets for powering the rides could act as the ballast; a more economical solution than having dead-weight as ballast on a tractor and providing a separate vehicle for the generators. Modern generators tend to be smaller and can fit between the cab and the fifth wheel of a conventional tractor unit, reducing the need for fairground use of ballast tractors. A vehicle used for towing fairground rides may also be called a "showman's diesel road locomotive", reflecting back to the steam-powered showman's road locomotive
s that originally provided this function.
A ballast tractor is somewhat limited in its use in modern day road freight because tractor-trailer combinations are more flexible and practical to move normal heavy loads. A heavy duty tractor unit equipped with a temporary ballast box may also be used as a normal fifth wheel -based tractor-unit, but its curb weight is often high thus reducing the payload of the entire vehicle, compared to a lighter-weight unit.
Built-to-order machines tend to be the heaviest and most powerful machines designed for one company for a specific purpose. Nicolas Tractomas (France) for example, currently builds 8x8 and 10x10 ultra-heavy-duty tractors for Rotran in South Africa.
Belgium
Canada
Czech Republic
France
Germany
Italy
Netherlands
Spain
Switzerland
UK
USA
Apart from being used by fairgrounds as a direct replacement for the steam-powered showman's engine, specialist moving and haulage companies use ballast tractors. These include:
(SPMT) and modular low loaders, pure ballast tractors are not as common, with most being a heavy duty tractor unit with a removable "Ballast" box fixed in place of the fifth wheel unit. Ultra heavy loads of 200 ton plus generally are only moved short distances and SPMT's are more manuverable. Items commonly moved include: oil rig modules, bridge sections, buildings, sections of ships, industrial machinery.
Haulage
Haulage may refer to:* The business of being a haulier or hauler , also called haulage contractor, common carrier, contract carrier, or private carrier, in other words of transporting goods by road or rail for other companies or one's own company.* The horizontal transport of ore, coal, supplies,...
road vehicle designed to pull or push heavy or exceptionally large loads. Unlike the tractor unit from an articulated trailer
Semi-trailer
A semi-trailer is a trailer without a front axle. A large proportion of its weight is supported by a road tractor, a detachable front axle assembly known as a dolly, or the tail of another trailer...
, the ballast tractor is designed or adapted to pull or push loads from a drawbar
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.-Agriculture:...
. By contrast an articulated tractor unit pulls from a "fifth wheel"
Fifth wheel coupling
The fifth wheel coupling provides the link between a semi-trailer and the towing truck, tractor unit, leading trailer or dolly. Some recreational vehicles use a fifth wheel configuration, requiring the coupling to be installed in the bed of a pickup truck as a towing vehicle...
, and only pushes when reversing its load.
Description
Sailing ballast
Ballast is used in sailboats to provide moment to resist the lateral forces on the sail. Insufficiently ballasted boats will tend to tip, or heel, excessively in high winds. Too much heel may result in the boat capsizing. If a sailing vessel should need to voyage without cargo then ballast of...
) describing heavy material added to a vessel to improve stability. For a ballast tractor, ballast is added over the driving wheels to increase the available tractive effort
Tractive effort
As used in mechanical engineering, the term tractive force is the pulling or pushing force exerted by a vehicle on another vehicle or object. The term tractive effort is synonymous with tractive force, and is often used in railway engineering to describe the pulling or pushing capability of a...
. The additional weight increases the friction between the tyres and the road surface. Without such ballast, the tractor would be unable to overcome the inertia and friction of rolling of a heavy trailed load, and its wheels would rotate without generating forward motion (termed wheelspin
Wheelspin
A wheelspin, occurs when the force delivered to the tire tread exceeds that of available tread-to-surface friction and one or more tires lose traction.Standard differentials always apply equal torque to each wheel...
). With a semi-trailer, the weight of the trailer presses down through the fifth wheel and adds ballast. In the case of a ballast tractor, the load is supported separately and its weight provides no ballast: the drawbar only transmits a horizontal force to the load.
High inertia
Inertia
Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass. The principle of inertia is one of the fundamental principles of classical physics which are used to...
is encountered when starting to move a heavy load. To overcome this, ballast tractors tend to have high power engines and engines that provide lots of torque
Torque
Torque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....
, especially at low speeds. Ballast tractors are often fitted with heavy duty hub reduction axle
Axle
An axle is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to its surroundings, with the wheels rotating around the axle. In the former case, bearings or bushings are provided at the mounting points where the axle...
s, or high reductive gear boxes to increase torque at the wheel, therefore heavy duty ballast tractors tend to have low maximum speeds.
A strong chassis
Chassis
A chassis consists of an internal framework that supports a man-made object. It is analogous to an animal's skeleton. An example of a chassis is the underpart of a motor vehicle, consisting of the frame with the wheels and machinery.- Vehicles :In the case of vehicles, the term chassis means the...
is required, to support the extra weight of the ballast and the pulling forces imposed by the drawbar. A reinforced chassis allows multiple tractors to be coupled together to increase the total power and traction available. Heavy-duty versions of commercial tractor units may be fitted with a ballast box and suitable drawgear, alternatively, a ballast tractor may be purpose-built for the role. The ballast is located above the driving axle, and tractors often have multiple driving axles to reduce the axle load, with the ballast distributed to avoid overloading a particular axle.
A ballast tractor that is built as a ballast tractor tends to be the heaviest class of on-highway trucks. In some cases, the weight of the chassis alone of these trucks (the kerb weight) can be even greater than their axle configuration legal Gross Vehicle Weight
Gross vehicle weight rating
A gross vehicle weight rating is the maximum allowable total weight of a road vehicle or trailer when loaded - i.e., including the weight of the vehicle itself plus passengers, and cargo....
(GVW) permits, so require special permission to use the roads.
Uses
The main use of ballast tractors is to move heavy and abnormal loads using an independent drawbar trailer, modular wheel-trailer units, or a dolly trailer. An advantage of using ballast tractors is that one can be used to push-steer a trailer around a corner. A girder trailer, for example, is double-articulated so the front tractor can pull the load around a corner whilst the rear tractor can push the rear end (at an angle) around the same corner. Therefore a push/pull combination can make an abnormal load more manoeuvrable than a rigid solution pulled by several tractors. Use of a following tractor can increase the control and brake force available when descending a hill.Another specialized use for ballast tractors is in showman vehicles. The ballast tractor used in this case may be a typical tractor unit fitted with a ballast box used to tow one or more specialized trailers that contain fairground rides which may not fit onto a standard fifth wheel connecting trailer. The overall weight of showman's vehicles tends to be much less than those used for heavy haulage to comply with vehicle weight legislation, particularly axle loads. Sometimes, one or more generator sets for powering the rides could act as the ballast; a more economical solution than having dead-weight as ballast on a tractor and providing a separate vehicle for the generators. Modern generators tend to be smaller and can fit between the cab and the fifth wheel of a conventional tractor unit, reducing the need for fairground use of ballast tractors. A vehicle used for towing fairground rides may also be called a "showman's diesel road locomotive", reflecting back to the steam-powered showman's road locomotive
Showman's road locomotive
A Showman's road locomotive or showman's engine is a steam-powered road-going 'locomotive' designed to provide power and transport for a travelling fair or circus...
s that originally provided this function.
A ballast tractor is somewhat limited in its use in modern day road freight because tractor-trailer combinations are more flexible and practical to move normal heavy loads. A heavy duty tractor unit equipped with a temporary ballast box may also be used as a normal fifth wheel -based tractor-unit, but its curb weight is often high thus reducing the payload of the entire vehicle, compared to a lighter-weight unit.
Manufacturers
Few well-known manufactures produce purpose-built ballast tractors. Most high-volume manufacturers offer heavy duty chassis versions of certain tractor units which enable a ballast box to be fitted. In Europe, manufacturers tend to send some of their products to another company (owned by the parent) to be converted into a special heavy duty version.Built-to-order machines tend to be the heaviest and most powerful machines designed for one company for a specific purpose. Nicolas Tractomas (France) for example, currently builds 8x8 and 10x10 ultra-heavy-duty tractors for Rotran in South Africa.
Belgium
- MOLMol-Places:* City Municipality of Ljubljana, known after the acronym MOL in Slovene language * Märkisch-Oderland, a rural district of Brandenburg, Germany* Mol, Belgium, a municipality in Belgium* Mol, Serbia, a town in Serbia...
Canada
- HayesHayes TruckHayes Manufacturing Company Limited was a Vancouver-based Canadian manufacturer of heavy trucks famed for their durability and a revolving bunk system. Hayes built both highway and off road trucks, particularly for the logging industry....
- PacificPacific trucksPacific Truck & Trailer Limited was a Vancouver-based Canadian manufacturer of heavy trucks famed for their durability. Pacific built both highway and off road trucks, particularly for the logging industry, heavy haulers and fire trucks....
Czech Republic
- Tatra
France
- Nicolas Tractomas
- PRPPRPPRP may stand for:* Park Royal Partnership in London* Patriotic Renewal Party or Partido Renovación Patriótica, a political party in Honduras* Peel Regional Police* People's Reconciliation Party* People's Republic of Poland* Personnel Reliability Program...
- WillèmeWillème-History:Willème was founded in 1923 by Louis Willeme, after working for Automobiles Grégoire.Most were made with Deutz AG engines; some with in-house engines; some with AEC. In the 1960s, Willème also sold rebadged AEC and BMC trucks....
Germany
- Faun GmbHFaun GmbHFaun GmbH is a German engineering firm, based in Pegnitz, Bavaria and owned by the Japanese company Tadano. They make mobile cranes.-History:*1845: Justus Christian Braun founded a bronze casting company in Germany....
- MAN (OAF)
- Mercedes Benz (Titan)
Italy
- Astra-SIVI (Iveco)
Netherlands
- DAFDAF TrucksDAF Trucks NV is a Dutch truck manufacturing company and a division of PACCAR. Its headquarters and main plant are in Eindhoven. Cabs and axle assemblies are produced at its Westerlo plant in Belgium...
(GINAF)
Spain
- BTO Trabosa
- TMUTMUTMU can refer to:* Tambor Airport, in Costa Rica * TrackMania United, a combined arcade racing game* Texture mapping unit, a component in modern computer graphics processing units* Taipei Medical University, Taipei City, Taiwan...
Switzerland
- NAWSaurerAdolph Saurer AG was a Arbon, Switzerland , based manufacturer of trucks and buses, under the Saurer and Berna brand names, and active between 1903 and 1982....
UK
- Atkinson Vehicles Ltd
- Foden TrucksFoden TrucksFoden Trucks was a British truck and bus manufacturing company which has its origins in Sandbach, Cheshire in 1856. PACCAR acquired the company in 1980, and ceased to use the marque name in 2006.-History:...
- Rotinoff Motors Ltd, SloughSloughSlough is a borough and unitary authority within the ceremonial county of Royal Berkshire, England. The town straddles the A4 Bath Road and the Great Western Main Line, west of central London...
– 35 heavy haulage tractors were built by the company between 1952 and 1959, of which 11 are known to survive.http://tractors.wikia.com/wiki/Rotinoff - Scammell LorriesScammell LorriesScammell Lorries Limited was a British manufacturer of trucks, particularly specialist and military off-highway vehicles, from 1921 to 1988.-History:...
– Many early examples, now used and seen as showman's vehicles, originally served with the army. - ThornycroftThornycroft AntarThe Mighty Antar was a heavy-duty tractor unit built by Thornycroft from the 1940s onwards. For some decades it was the standard tank transporter of the British Army and was also used by other nations.- History :- Origins :...
- UnipowerUnipowerThe Unipower GT was a British specialist sports car first shown at the January 1966 Racing Car Show, and produced by truck maker Universal Power Drives Ltd in Perivale, Middlesex and later by U.W.F...
USA
- Diamond TDiamond TThe Diamond T was an American automobile manufactured in Chicago from 1905 until 1911 by the Diamond T Motor Car Company. It was a powerful touring car . The company later became known for its trucks...
- Ex-army tank transports were popular post-warWorld War IIWorld War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
with heavy hauliers in the UK. - KenworthKenworthKenworth is an American manufacturer of medium and heavy-duty Class 8 trucks based in Kirkland, Washington, United States, a suburb of Seattle. It is a subsidiary of PACCAR, and is also a former manufacturer of transit buses and school buses.-History:...
- MackMack TrucksMack Trucks is an American truck-manufacturing company and a former manufacturer of buses and trolley buses. A wholly owned subsidiary of Renault Véhicules Industriels since 1990, Mack Trucks is currently a subsidiary of AB Volvo. The company's headquarters are located in Greensboro, North Carolina...
- WhiteWhite Motor CompanyWhite Motor Company was an American automobile and truck manufacturer from 1900 until 1980. The company also produced bicycles, roller skates, automatic lathes, and sewing machines. Before World War II, the company was based in Cleveland, Ohio.-History:...
- Oshkosh Corporation
Operators
Most heavy haulage and heavy lift engineering firms employ heavy duty tractor-unit models that can accommodate a ballast box. Countries where modernisation is taking place, such as regions of the Middle East and South Africa, operate larger number of ballast tractors due to the greater frequency of heavy loads (such as power station components).Apart from being used by fairgrounds as a direct replacement for the steam-powered showman's engine, specialist moving and haulage companies use ballast tractors. These include:
- Abnormal Load Engineering - specialist in moving transformers and turbines for power stations, from GEC at Stafford.
- AlstomAlstomAlstom is a large multinational conglomerate which holds interests in the power generation and transport markets. According to the company website, in the years 2010-2011 Alstom had annual sales of over €20.9 billion, and employed more than 85,000 people in 70 countries. Alstom's headquarters are...
- MammoetMammoetMammoet is a privately held Dutch company specializing in the hoisting and transporting of heavy objects.- History :Mammoet was founded in 1973, specialised in heavy transport over water and roads. In 2001 it was taken over by Van Seumeren transport. The name Mammoet became the name for the new...
- PickfordsPickfordsPickfords is a moving company based in the United Kingdom, part of the Moving Services Group UK Ltd.The business is believed to have been founded in the 17th century, making it one of the UK's oldest functioning companies. The earliest record is of a William Pickford, a carrier who worked south of...
Alternatives
With the increasing versatility of Self Propelled Modular TransporterSelf Propelled Modular Transporter
A Self Propelled Modular Transporter is a platform vehicle with a large array of wheels on the bottom. They are used for transporting massive objects such as bridges, oil refining equipment, huge motors, large bridge sections, and other objects that are too big or heavy for trucks but trucks can...
(SPMT) and modular low loaders, pure ballast tractors are not as common, with most being a heavy duty tractor unit with a removable "Ballast" box fixed in place of the fifth wheel unit. Ultra heavy loads of 200 ton plus generally are only moved short distances and SPMT's are more manuverable. Items commonly moved include: oil rig modules, bridge sections, buildings, sections of ships, industrial machinery.
See also
- Prime mover
- ToterToterA Toter, or Mobile Home Toter is a tractor specifically designed for the modular and manufactured housing industries. Some toters are highly adapted for purposes of delivering or removing mobile homes on smaller home sites...
- Tractor unitTractor unitA tractor unit, prime mover , road tractor, or traction unit is a heavy-duty commercial vehicle within the large goods vehicle category, usually with a large displacement diesel engine, and several axles. The tractor unit serves as a method of moving trailers...
- Heavy haulerHeavy haulerA heavy hauler is a very large transporter for moving oversize loads which are toolarge to go on a highway without an escort and special permit.-Types of vehicles:...
- Road locomotive – steam-powered fore-runner of the ballast tractor
External links
- Wiki with further information about heavy haulage specialist featuring photos of trucks
- Extremely large collection of heavy haulage photos