A tractor unit , also known as a truck unit , lorry unit , power unit , prime mover , ten-wheeler , semi-tractor , semi-truck , semi-lorry , tractor cab , truck cab , lorry cab , big rig tractor , big rig truck or big rig lorry or simply a tractor , truck , lorry , semi , big rig or rig , is a characteristically heavy-duty towing engine that provides motive power for hauling a towed or trailered load. These fall into two categories: heavy- and medium-duty military and commercial rear-wheel-drive semi-tractors used for hauling semi-trailers , and very heavy-duty typically off-road -capable, often 6×6 , military and commercial tractor units, including ballast tractors .
55-661: The Bedford TK was a truck manufactured by Bedford . Launched in 1960 to replace the Bedford S type , the TK was scheduled to be replaced by the Bedford TL in 1981, but manufacturing of the TK continued as a cheaper alternative. A military 4x4 version, the Bedford MK (later MJ ), was also produced. After Bedford's Dunstable factory was sold in 1987 to AWD , the TK restarted production for military only use until 1992 when AWD
110-406: A fifth wheel hitch. Box trucks have walls and a roof, making an enclosed load space. The rear has doors for unloading; a side door is sometimes fitted. Chassis cab trucks have a fully enclosed cab at the front, with bare chassis frame-rails behind, suitable for subsequent permanent attachment of a specialized payload, like a fire-truck or ambulance body. Concrete mixers have
165-453: A gross combination mass of up to 3.5 t (3.4 long tons; 3.9 short tons) are defined as light commercial vehicles , and those over as large goods vehicles . Trucks and cars have a common ancestor: the steam-powered fardier Nicolas-Joseph Cugnot built in 1769. However, steam wagons were not common until the mid-19th century. The roads of the time, built for horse and carriages, limited these vehicles to very short hauls, usually from
220-456: A tractor unit describes only the tractor portion. Tractor units typically have large-displacement diesel engines for power, durability, and economy; several axles ; and a multi-ratio transmission (10, 13, or 18 gears) for maximum flexibility in gearing. The tractor–trailer combination distributes a load across multiple axles while being more maneuverable than an equivalently sized rigid truck . The most common trailer attachment system
275-485: A 25 mph (40 km/h) speed governor as they are classified as low-speed vehicles. These vehicles have found uses in construction, large campuses (government, university, and industrial), agriculture, cattle ranches, amusement parks, and replacements for golf carts. Major mini-truck manufacturers and their brands include: Daihatsu Hijet , Honda Acty , Tata Ace , Mazda Scrum , Mitsubishi Minicab , Subaru Sambar , and Suzuki Carry . Light trucks are car-sized (in
330-430: A cabin that is independent of the payload portion of the vehicle. Smaller varieties may be mechanically similar to some automobiles . Commercial trucks can be very large and powerful and may be configured to be mounted with specialized equipment, such as in the case of refuse trucks , fire trucks , concrete mixers , and suction excavators . In American English, a commercial vehicle without a trailer or other articulation
385-401: A common construction: they are made of a chassis , a cab , an area for placing cargo or equipment, axles , suspension and roadwheels , an engine and a drivetrain . Pneumatic , hydraulic , water , and electrical systems may also be present. Many also tow one or more trailers or semi-trailers. The "cab", or "cabin" is an enclosed space where the driver is seated. A " sleeper " is
440-711: A compartment attached to or integral with the cab where the driver can rest while not driving, sometimes seen in semi-trailer trucks. There are several cab configurations: A further step from this is the side loading forklift that can be described as a specially fabricated vehicle with the same properties as a truck of this type, in addition to the ability to pick up its own load. Most small trucks such as sport utility vehicles (SUVs), vans or pickups , and even light medium-duty trucks in North America, China, and Russia use gasoline engines (petrol engines), but many diesel engined models are now being produced. Most of
495-580: A factory to the nearest railway station. The first semi-trailer appeared in 1881, towed by a steam tractor manufactured by De Dion-Bouton . Steam-powered wagons were sold in France and the United States until the eve of World War I , and 1935 in the United Kingdom, when a change in road tax rules made them uneconomic against the new diesel lorries. In 1895, Karl Benz designed and built
550-406: A ladder if tipped on end. The rails consist of a tall vertical section (two if boxed) and two shorter horizontal flanges. The height of the vertical section provides opposition to vertical flex when weight is applied to the top of the frame (beam resistance). Though typically flat the whole length on heavy-duty trucks, the rails may sometimes be tapered or arched for clearance around the engine or over
605-420: A manual transmission with synchromesh (synchronizers). Bigger trucks often use manual transmissions without synchronizers, saving bulk and weight, although synchromesh transmissions are used in larger trucks as well. Transmissions without synchronizers, known as "crash boxes", require double-clutching for each shift, (which can lead to repetitive motion injuries), or a technique known colloquially as "floating",
SECTION 10
#1732798559327660-545: A manual transmission, while conventional automatic or automated manual transmissions would have anything from 5 to 12 gears. Almost all heavy truck transmissions are of the "range and split" (double H shift pattern) type, where range change and so‑called half gears or splits are air operated and always preselected before the main gear selection. A truck frame consists of two parallel boxed (tubular) or C‑shaped rails, or beams, held together by crossmembers . These frames are referred to as ladder frames due to their resemblance to
715-407: A method of changing gears which does not use the clutch, except for starts and stops, due to the physical effort of double-clutching, especially with non-power-assisted clutches, faster shifts, and less clutch wear. Double-clutching allows the driver to control the engine and transmission revolutions to synchronize so that a smooth shift can be made; for example, when upshifting, the accelerator pedal
770-510: A more uncertain origin, but probably has its roots in the rail transport industry, where the word is known to have been used in 1838 to refer to a type of truck (a goods wagon as in British usage, not a bogie as in the American), specifically a large flat wagon. It might derive from the verb lurry (to carry or drag along, or to lug) which was in use as early as 1664, but that association
825-401: A roof and floor, used for transporting fresh and frozen cargo such as ice cream, food, vegetables, and prescription drugs. They are mostly equipped with double-wing rear doors, but a side door is sometimes fitted. Refuse trucks have a specialized body for collecting and, often, compacting trash collected from municipal, commercial, and industrial sites. This application has the widest use of
880-547: A rotating drum on an inclined axis, rotating in one direction to mix, and in the other to discharge the concrete down chutes. Because of the weight and power requirements of the drum body and rough construction sites, mixers have to be very heavy duty. Dual drive/Steer trucks are vehicles used to steer the rear of trailers . Dump trucks ("tippers" in the UK) transport loose material such as sand, gravel, or dirt for construction. A typical dump truck has an open-box bed, which
935-709: A six-axle truck may have a maximum weight of 44 t (97,000 lb) or more. Off-road trucks include standard, extra heavy-duty highway-legal trucks, typically outfitted with off-road features such as a front driving axle and special tires for applications such as logging and construction, and purpose-built off-road vehicles unconstrained by weight limits, such as the Liebherr T 282B mining truck. Australia has complex regulations over weight and length, including axle spacing, type of axle/axle group, rear overhang, kingpin to rear of trailer, drawbar length, ground clearance, as well as height and width laws. These limits are some of
990-411: A truck, of a trailer, from axle to hitch point, kingpin to rear of trailer, and turning radius are all regulated. In additions, there are special rules for carrying containers, and countries can set their own rules for local traffic. The United States Federal Bridge Law deals with the relation between the gross weight of the truck, the number of axles, the weight on and the spacing between the axles that
1045-622: A version of their Xebra electric tricycle (licensable in the U.S. as a motorcycle). Popular in Europe and Asia, many mini-trucks are factory redesigns of light automobiles, usually with monocoque bodies. Specialized designs with substantial frames such as the Italian Piaggio shown here are based upon Japanese designs (in this case by Daihatsu ) and are popular for use in "old town" sections of European cities that often have very narrow alleyways. Regardless of name, these small trucks serve
1100-573: A wide range of uses. In Japan, they are regulated under the Kei car laws, which allow vehicle owners a break in taxes for buying a smaller and less-powerful vehicle (currently, the engine is limited to 660 cc displacement). These vehicles are used as on-road utility vehicles in Japan. These Japanese-made mini-trucks that were manufactured for on-road use are competing with off-road ATVs in the United States, and import regulations require that these mini-trucks have
1155-519: Is a fifth-wheel coupling , allowing a rapid shift between trailers performing different functions, such as a bulk tipper and box trailer . Trailers containing differing cargos can be rapidly swapped between tractors, eliminating downtime while a trailer is unloaded or loaded. Drawbar couplings are also found, particularly in dedicated exceptionally heavy-duty ballast tractors and as a means to connect intermediate fifth-wheel dollies for pulling multiple semi-trailers. Most tractor units are based on
SECTION 20
#17327985593271210-578: Is formally a "straight truck" while one designed specifically to pull a trailer is not a truck but a " tractor ". The majority of trucks currently in use are powered by diesel engines , although small- to medium-size trucks with gasoline engines exist in North America . Electrically powered trucks are more popular in China and Europe than elsewhere. In the European Union , vehicles with
1265-427: Is hinged at the rear and lifts at the front, allowing the material in the bed to be unloaded ("dumped") on the ground behind the truck. Flatbed trucks have an entirely flat, level platform body. This allows for quick and easy loading but has no protection for the load. Hanging or removable sides are sometimes fitted, often in the form of a stakebody . Refrigerator trucks have insulated panels as walls and
1320-422: Is in neutral, it allows the engine speed to drop and synchronize engine and transmission revolutions relative to the road speed. Downshifting is performed in a similar fashion, except the engine speed is now required to increase (while the transmission is in neutral) just the right amount in order to achieve the synchronization for a smooth, non-collision gear change. "Skip changing" is also widely used; in principle,
1375-573: Is most often made as vans. Medium trucks are larger than light but smaller than heavy trucks. In the US, they are defined as weighing between 13,000 and 33,000 lb (5.9 and 15.0 t). For the UK and the EU the weight is between 3.5 and 7.5 t (7,700 and 16,500 lb). Local delivery and public service ( dump trucks , garbage trucks and fire-fighting trucks ) are normally around this size. Heavy trucks are
1430-461: Is mostly reserved for larger vehicles. In Australia and New Zealand, a pickup truck is frequently called a ute (short for "utility" vehicle), while in South Africa it is called a bakkie ( Afrikaans : "small open container"). In the United Kingdom, India, Malaysia, Singapore, Ireland, and Hong Kong lorry is used instead of truck , but only for the medium and heavy types, while truck
1485-469: Is not definitive. The expanded meaning of lorry , "self-propelled vehicle for carrying goods", has been in usage since 1911. In the United States, Canada, and the Philippines, "truck" is usually reserved for commercial vehicles larger than regular passenger cars, but includes large SUVs, pickups, and other vehicles with an open load bed. In Australia, New Zealand and South Africa, the word "truck"
1540-412: Is released and the clutch pedal is depressed while the gear lever is moved into neutral, the clutch pedal is then released and quickly pushed down again while the gear lever is moved to the next higher gear. Finally, the clutch pedal is released and the accelerator pedal pushed down to obtain the required engine speed. Although this is a relatively fast movement, perhaps a second or so while the transmission
1595-516: Is used almost exclusively to refer to pickups . Often produced as variations of golf cars , with internal combustion or battery electric drive , these are used typically for off-highway use on estates, golf courses, and parks. While not suitable for highway use some variations may be licensed as slow speed vehicles for operation on streets, generally as a body variation of a neighborhood electric vehicle . A few manufactures produce specialized chassis for this type of vehicle, while Zap Motors markets
1650-786: The British Armed Forces and others. The Bedford MK was introduced in 1970 to replace the Bedford RL . It was very successful with over 50,000 produced. The MK/MJ was produced in many variants. From April 1981, Bedford changed the designation of the MK to MJ as the K multi-fuel engine was superseded by the J diesel engine. It was confirmed in March 2014 that, with the exception of a handful of light recovery vehicles, all British Army Bedford MK/MJ trucks had been disposed of, replaced by RMMV HX60 4x4 trucks. After Bedford's Dunstable factory
1705-434: The cab-over configuration in North America, to provide better maneuverability in tight situations. They are also among the most severe-duty and highest GVWR trucks on public roads. Semi-tractors ("artics" in the UK) have a fifth wheel for towing a semi-trailer instead of a body. Tractor unit It should not be confused with a tractor-trailer which is a combination of a tractor unit and semi-trailer , whereas
Bedford TK - Misplaced Pages Continue
1760-422: The diesel engine did not appear in production trucks until Benz introduced it in 1923. The diesel engine was not common in trucks in Europe until the 1930s. In the United States, Autocar introduced diesel engines for heavy applications in the mid-1930s. Demand was high enough that Autocar launched the "DC" model (diesel conventional) in 1939. However, it took much longer for diesel engines to be broadly accepted in
1815-461: The phase-out of fossil fuel vehicles includes trucks. According to The Economist magazine "Electric lorries will probably run on hydrogen, not batteries, which are too expensive." Other researchers say that once faster chargers are available batteries will become competitive against diesel for all, except perhaps the heaviest, trucks. Small trucks use the same type of transmissions as almost all cars, having either an automatic transmission or
1870-617: The TK was the quintessential light truck in the United Kingdom through most of the 1960s and 1970s, competing with the similar Ford D series . It was available in rigid form, and also as a light tractor unit normally using the Scammell coupling form of semi-trailer attachment. In 1981, Bedford introduced turbocharging to the "Red Series" 3.6-litre and 5.4-litre diesel engines, now producing 72 bhp and 102 bhp respectively. TKs were assembled for many years by General Motors New Zealand (GMNZ) at its Petone truck plant. The model
1925-545: The US, no more than 13,900 lb (6.3 t)) and are used by individuals and businesses alike. In the EU they may not weigh more than 3.5 t (7,700 lb) and are allowed to be driven with a driving licence for cars. Pickup trucks , called utes in Australia and New Zealand, are common in North America and some regions of Latin America, Asia, and Africa, but not so in Europe, where this size of commercial vehicle
1980-558: The US: gasoline engines were still in use on heavy trucks in the 1970s. Electrically powered trucks predate internal combustion ones and have been continuously available since the mid-19th-century. In the 1920s Autocar Trucks was the first of the major truck manufacturers to offer a range of electric trucks for sale. Electric trucks were successful for urban delivery roles and as specialized work vehicles like forklifts and pushback tugs . The higher energy density of liquid fuels soon led to
2035-403: The axles. The holes in rails are used either for mounting vehicle components and running wires and hoses or measuring and adjusting the orientation of the rails at the factory or repair shop. The frame is usually made of steel , but can be made (whole or in part) of aluminum for a lighter weight. A tow bar may be found attached at one or both ends, but heavy tractors almost always make use of
2090-685: The chassis of a large truck (Class 8 in North America) minus the cargo body, with shorter frames used for cabovers and day-cab tractors, and longer frames used for Sleeper cab tractors, to accommodate the longer cabin. There have been three common cab configurations used in tractors, two are still widely used. A tractor unit can have many axles depending on axle load legislation . The most common varieties are those of 4×2, 6×2, and 6×4 types . However, some manufacturers offer 4×4, 6×6, 8x4, 8×6, 8×8, 10×8, and 10×10 axle configurations. A 6×4 has three axles, normally an undriven front steer axle and
2145-431: The decline of electric-powered trucks in favor of, first, gasoline, and then diesel and CNG-fueled engines until battery technology advanced in the 2000s when new chemistries and higher-volume production broadened the range of applicability of electric propulsion to trucks in many more roles. Today, manufacturers are electrifying all trucks ahead of national regulatory requirements, with long-range over-the-road trucks being
2200-405: The driven axle. The 6×6 units have three axles, all can be driven, and 8×6 units have four axles, with either the rear three driven and the front axle not, or the front and rear-most two axles powered and an unpowered lifting center axle to spread the load when needed. The 8×8 units also have four axles, but with all of them driven, and 10×8 units have five axles with the rear four usually driven and
2255-493: The first internal combustion truck. Later that year some of Benz's trucks were modified to become busses by Netphener . A year later, in 1896, another internal combustion engine truck was built by Gottlieb Daimler , the Daimler Motor Lastwagen . Other companies, such as Peugeot , Renault and Büssing , also built their own versions. The first truck in the United States was built by Autocar in 1899 and
Bedford TK - Misplaced Pages Continue
2310-440: The front axle for steering. All five axles of 10×10 units are driven. The front two axles are usually both steer axles. The axle configurations are usually based on axle load legislation, and maximum gross vehicle weight ratings (BDM). Heavier versions of tractor units, such as those used in heavy haulage and road trains , tend to have four or more axles, with more than two axles driven. In certain countries (such as Switzerland),
2365-443: The heavier trucks use four-stroke diesel engines with a turbocharger and intercooler . Huge off-highway trucks use locomotive-type engines such as a V12 Detroit Diesel two stroke engine. A large proportion of refuse trucks in the United States employ CNG (compressed natural gas) engines for their low fuel cost and reduced carbon emissions. A significant proportion of North American manufactured trucks use an engine built by
2420-440: The highest in the world, a B-double can weigh 62.5 t (61.5 long tons; 68.9 short tons) and be 25 m (82 ft) long, and road trains used in the outback can weigh 172 t (169.3 long tons; 189.6 short tons) and be 53.5 m (176 ft) long. The European Union also has complex regulations. The number and spacing of axles, steering, single or dual tires, and suspension type all affect maximum weights. Length of
2475-407: The largest on-road trucks, Class 8 . These include vocational applications such as heavy dump trucks, concrete pump trucks, and refuse hauling, as well as ubiquitous long-haul 4x2 and 6×4 tractor units . Road damage and wear increase very rapidly with the axle weight. The number of steering axles and the suspension type also influence the amount of the road wear. In many countries with good roads
2530-521: The last remaining major independent engine manufacturer ( Cummins ) but most global OEMs such as Volvo Trucks and Daimler AG promote their own "captive" engines. In the European Union, all new truck engines must comply with Euro VI emission regulations, and Euro 7 from the late 2020s has stricter exhaust limits and also limits air pollution from brakes and tires . As of 2019 several alternative technologies are competing to displace
2585-662: The most challenging. Truck is used in American English ; the British English equivalent is lorry. The first known usage of "truck" was in 1611 when it referred to the small strong wheels on ships' cannon carriages, and comes from "Trokhos" (Greek) = "wheel". In its extended usage, it came to refer to carts for carrying heavy loads, a meaning known since 1771. Its expanded application to "motor-powered load carrier" has been in usage since 1930, shortened from "motor truck", which dates back to 1901. "Lorry" has
2640-424: The operation is the same as double-clutching, but it requires neutral be held slightly longer than a single-gear change. Common North American setups include 9, 10, 13, 15, and 18 speeds. Automatic and automated manual transmissions for heavy trucks are becoming more and more common, due to advances both in transmission and engine power. In Europe, 8, 10, 12, and 16 gears are common on larger trucks with
2695-592: The truck can have on the Interstate highway system. Each State determines the maximum permissible vehicle , combination , and axle weight on state and local roads. Uniquely, the State of Michigan has a gross vehicle weight limit of 164,000 lb (74 t), which is twice the U.S. federal limit. A measure to change the law was defeated in the Michigan Senate in 2019. Almost all trucks share
2750-479: The two rear axles driven. 6×4 units are more common in long-distance haulage in larger countries such as the United States and Australia. In Europe , the 4×2 and 6×2 variants are more commonplace. Tractors with three axles or more can have more than one steering axle, which can also be driven. Most 6×2 units allow the undriven rear axle to be raised when lightly loaded, or running without a trailer, to save tire wear, save toll road fees, and increase traction on
2805-405: The use of diesel engines in heavy trucks. CNG engines are widely used in the US refuse industry and in concrete mixers, among other short-range vocations, but range limitations have prevented their broader uptake in freight hauling applications. Heavy electric trucks and hydrogen-powered trucks are new to the market in 2021, but major freight haulers are interested. Although cars will be first
SECTION 50
#17327985593272860-635: Was available with 5 or 8 horsepower (4 or 6 kW) engines. Another early American truck was built by George Eldridge of Des Moines, Iowa, in 1903. It was powered by an engine with two opposed cylinders, and had a chain drive A 1903 Eldridge truck is displayed at the Iowa 80 Trucking Museum, Walcott, Iowa. Trucks of the era mostly used two-cylinder engines and had a carrying capacity of 1.5 to 2 t (3,300 to 4,400 lb). After World War I, several advances were made: electric starters , and 4, 6, and 8 cylinder engines. Although it had been invented in 1897,
2915-558: Was placed in receivership. The TK range replaced the Bedford S type in 1960, and served as the basis for a variety of derivatives, including fire engines , military , horse carriers , tippers , flatbed trucks , and other specialist utilities. A General Post Office (later British Telecom ) version used for installing telegraph poles was known as the Pole King. Available with inline four or inline six cylinder petrol and diesel engines from Bedford, Leyland and Perkins ,
2970-403: Was sold in 1987 to AWD , the MK restarted production for military only use until 1992 when AWD was placed in receivership. Truck A truck or lorry is a motor vehicle designed to transport freight , carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construction, with
3025-448: Was very popular and competed with the like of the also locally assembled Ford D series. It was succeeded by the TM series and GMNZ later switched source to launch a range of Bedford-by- Isuzu models assembled locally from kits shipped from Japan. Over 500,000 were produced. They were also assembled by Holden in Australia. The Bedford MK/MJ was a 4x4 variant of the TK used in large numbers by
#326673