Off-highway dump trucks^[24] are heavy construction equipment and share little resemblance to highway dump trucks. Bigger off-highway dump trucks are used strictly off-road for mining and heavy dirt hauling jobs. There are two primary forms: rigid frame and articulating frame.

The term “dump” truck is not generally used by the mining industry, or by the manufacturers that build these machines. The more appropriate U.S. term for this strictly off-road vehicle is “haul truck” and the equivalent European term is “dumper”.

Haul truck[edit]

Main article: Haul truck

Small 200 Ton Caterpillar Haul truck.

Haul trucks are used in large surface mines and quarries. They have a rigid frame and conventional steering with drive at the rear wheel. As of late 2013, the largest ever production haul truck is the 450 metric ton BelAZ 75710, followed by the Liebherr T 282B, the Bucyrus MT6300AC and the Caterpillar 797F, which each have payload capacities of up to 400 short tons (363 t; 357 long tons). Most large-size haul trucks employ Diesel-electric powertrains, using the Diesel engine to drive an AC alternator or DC generator that sends electric power to electric motors at each rear wheel. The Caterpillar 797 is unique for its size, as it employs a Diesel engine to power a mechanical powertrain, typical of most road-going vehicles and intermediary size haul trucks. Other major manufacturers of haul trucks include SANY, XCMG, Hitachi, Komatsu, DAC, Terex, and BelAZ.

Articulated hauler[edit]

Main article: Articulated hauler

Articulated dump truck or dumper

An articulated dumper is an all-wheel-drive, off-road dump truck. It has a hinge between the cab and the dump box but is distinct from a semi-trailer truck in that the power unit is a permanent fixture, not a separable vehicle. Steering is accomplished via hydraulic cylinders that pivot the entire tractor in relation to the trailer, rather than rack and pinion steering on the front axle as in a conventional dump truck. By this way of steering, the trailer’s wheels follow the same path as the front wheels. Together with all-wheel drive and low center of gravity, it is highly adaptable to rough terrain. Major manufacturers include Volvo CE, Terex, John Deere, and Caterpillar.