Eight-wheel drive, often notated as 8WD or 8×8, is a drivetrain configuration that allows all eight wheels of an eight-wheeled vehicle to be drive wheels (that is, to receive power from the engine) simultaneously. Unlike four-wheel drive drivetrains, the configuration is largely confined to heavy-duty off-road and military vehicles, such as all-terrain vehicles, armored vehicles, and prime movers. Other types of smaller 8x8 vehicles include such things as the Argocat.
When such a vehicle only has eight wheels by definition all are driven. When it has twelve – with two pairs of ganged "dual" wheels on each rear axle – all are also driven but the 8×8 designation remains. Very occasionally, on the Sterling T26 for example, the two front axles can be fitted with ganged "dual" wheels.For most military applications where traction/mobility are considered more important than payload capability, single wheels on each axle (often referred to as super singles) are the norm. On some vehicles, usually recovery trucks or heavy tractor units, the rear two axles will have wider single tires than the front two axles.
Heavy hauler and ballast tractor 8×8s have had a long history as prime movers both in the military (as tank transports and artillery tractors), and commercially in logging and heavy equipment hauling both on- and off-road. Most eight-wheel drive trucks have two forward axles and two at the rear, with only the front pair steering. Occasionally a single front axle and three rear (tridem) are seen, an example being the Oshkosh M1070 tank transporter. In such configurations, the front and rear axle usually steer.Other set ups include that of the ZIL-135.
Many wheeled armored vehicles have an 8x8 driveline, and on these the axles (which usually have independent suspension) are more evenly spaced. Latest generation 8x8 wheeled armored vehicles have steering on the rearmost (fourth) axle to improve mobility in urban and confined situations.
In the case of both truck and armored vehicle applications, drive may be limited to the rear two axles for on-road use, this reducing driveline stress and tire wear, and increasing fuel efficiency.
The Heavy Expanded Mobility Tactical Truck (HEMTT) is an eight-wheel drive, diesel-powered, 10-short-ton (9,100 kg), tactical truck used by the US military and others. In evolving configurations, it has been in continuous production since 1982. The M977 HEMTT entered service with the U.S. Army as a replacement for the M520 Goer.
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 the vehicle, with the wheels rotating around the axle. In the former case, bearings or bushings are provided at the mounting points where the axle is supported. In the latter case, a bearing or bushing sits inside a central hole in the wheel to allow the wheel or gear to rotate around the axle. Sometimes, especially on bicycles, the latter type axle is referred to as a spindle.
Four-wheel drive, also called 4x4 or 4WD, refers to a two-axled vehicle drivetrain capable of providing torque to all of its wheels simultaneously. It may be full-time or on-demand, and is typically linked via a transfer case providing an additional output drive shaft and, in many instances, additional gear ranges.
A half-track is a civilian or military vehicle with regular wheels at the front for steering and continuous tracks at the back to propel the vehicle and carry most of the load. The purpose of this combination is to produce a vehicle with the cross-country capabilities of a tank and the handling of a wheeled vehicle.
A locking differential is designed to overcome the chief limitation of a standard open differential by essentially "locking" both wheels on an axle together as if on a common shaft. This forces both wheels to turn in unison, regardless of the traction available to either wheel individually.
A dump truck, known also as a dumper truck or tipper truck, is used for taking dumps for construction as well as coal. A typical dump truck is equipped with an open-box bed, which is hinged at the rear and equipped with hydraulic rams to lift the front, allowing the material in the bed to be deposited ("dumped") on the ground behind the truck at the site of delivery. In the UK, Australia and India the term applies to off-road construction plant only, and the road vehicle is known as a tipper lorry, tip-truck, tip-trailer, tipper truck, or tipper.
Oshkosh Corporation, formerly Oshkosh Truck, is an American industrial company that designs and builds specialty trucks, military vehicles, truck bodies, airport fire apparatus and access equipment. The corporation also owns Pierce Manufacturing, a fire apparatus manufacturer in Appleton, Wisconsin. Based in Oshkosh, Wisconsin, the company employs approximately 16,000 people around the world. It is organized in four primary business groups: access equipment, defense, fire and emergency, and commercial.
The Medium Tactical Vehicle Replacement (MTVR) is a series of vehicles, based on a common chassis that vary by payload and mission requirements. The MTVR is a purpose-designed military vehicle, although a small number of vehicles have been sold commercially for specialized operations such as wildfire fighting.
Six-wheel drive is an all-wheel drive drivetrain configuration of three axles with at least two wheels on each axle capable of being driven simultaneously by the vehicle's engine. Unlike four-wheel drive drivetrains, the configuration is largely confined to heavy-duty off-road and military vehicles, such as all-terrain vehicles, armored vehicles, and prime movers.
The Palletized Load System (PLS) is a truck-based logistics system that entered service in the United States Army in 1993. It performs line haul, local haul, unit resupply, and other missions in the tactical environment to support modernized and highly mobile combat units. It provides rapid movement of combat configured loads of ammunition and all classes of supply, shelters and containers. It mirrors similar systems in use with the British and other armed forces.
A tractor unit 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.
The TatraT813 was a truck produced in Czechoslovakia by the Tatra company. It was produced from 1967 to 1982. The basic representative of this series was a military version of the 8×8 Kolos (Colossus), which was able to pull trailers up to a total weight of 100 tons. Tatra also produced a civilian version in either 6×6 or 4×4. After fifteen years of production, 11,751 vehicles were built in all modifications. Many units were exported to the USSR, East Germany, Romania and India.
The M520 "Truck, Cargo, 8-ton, 4x4", nicknamed Goer, truck series was formerly the US Army’s standard heavy tactical truck before its replacement by the Oshkosh HEMTT. As trucks go, the Caterpillar 'Goer' stands out, due to being articulated, much wider than other trucks, and lacking suspension on the wheels.
A tank transporter is a combination of a heavy tractor unit and a mating full trailer or semi-trailer, used for transporting tanks and other AFVs. Some also function as tank recovery vehicles, the tractors of which may be armored for protection in combat conditions.
Ten-wheel drive, 10WD or 10×10 is a drivetrain configuration of ten wheels, all of which are driven simultaneously by the engine. Unlike four-wheel drive drivetrains, this configuration is only used in extreme off-road and military uses, in particular heavy duty uses, such a heavy haulage and missile carriers. It is also used in lorries.
Twelve-wheel drive, 12WD or 12x12 is a drivetrain configuration of twelve wheels, all of which are driven simultaneously by the engine.
An H-drive drivetrain is a system used for heavy off-road vehicles with 6×6 or 8×8 drive to supply power to each wheel station.
A 6×4 drivetrain (six-by-four) is a vehicle with a drivetrain of three axles delivering power to two wheel ends on two of them. It is a form of four-wheel drive but not one of all-wheel drive.
The Oshkosh M1070 is a U.S. Army tank transporter tractor unit. In current service in A0 and A1 configurations, the M1070 is coupled to a DRS Technologies M1000 semi-trailer. The primary purpose of this combination is the transport of the M1 Abrams tank.
The Logistic Vehicle System Replacement (LVSR) is a family of vehicles, based on a common 5-axle ten-wheel drive (10x10) chassis, that vary in individual configuration by mission requirements. The LVSR was designed and is manufactured by Oshkosh Defense. LVSR is a purpose-designed military vehicle and there are currently three variants in service, a cargo, a wrecker and a tractor truck.
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