Haul trucks are off-highway, rigid dump trucks specifically engineered for use in high-production mining and heavy-duty construction environments. Haul trucks are also used for transporting construction equipment from job site to job site. Some are multi-axle in order to support the equipment that is being hauled.
Most haul trucks have a two-axle design, but two well-known models from the 1970s, the 350T Terex Titan and 235T Wabco 3200/B, had three axles. Haul truck capacities range from to .
Large quarry-sized trucks range from . A good example of this is the Caterpillar 775 (rated at ). Quarry operations are typically smaller than, say, a gold/copper mine, and require smaller trucks.
As a rule, these dump trucks can be distinguished from other trucks (in particular, dump truck) by the following features:
the tipper body is made of very strong steel plate; its front is extended above the driver's cab to protect the cab; the entire bottom, or rear of it, points upward;
in some cases the driver's cab is only half the width of the truck;
no axle suspension;
powerful brakes;
limited speed and operating range;
special tires used for driving on the ground;
due to the robust design the ratio of dead weight to payload does not exceed 1:1.6
the body can be heated by exhaust gases to prevent the transported material from sticking or freezing.
Dump trucks are classified by:
type of unloading (inclined or forced);
the direction of discharge (side, rear);
type of body (hopper, platform, sliding hopper, sliding platform).
The largest, highest-payload-capacity haul trucks are referred to as ultra class trucks. The ultra class includes all haul trucks with a payload capacity of or greater. , the BelAZ 75710 has the highest payload capacity, .
A rear-eject configuration is an alternative haul truck body style. Instead of lifting the bed vertically, the hydraulic cylinder pushes a ram-face horizontally through the body to eject the hauled load.
Rear-eject dump vehicles were first introduced in the 1980s by LeRoy Hagenbuch, P.E.