Types of dump trucks

Dump trucks come in a variety of configurations each specified to accomplish a specific task in the construction material supply chain.

Standard dump truck

Another kind of 8x4 dump truck: three rear (two powered) axles

A standard dump truck is a full truck chassis with a dump body mounted to the frame. The dump body is raised by a hydraulic ram mounted forward of the front bulkhead, between the truck cab (traction unit) and the dump body (semi-trailer). The tailgate can be configured to swing on hinges or it can be configured in the "High Lift Tailgate" format wherein pneumatic rams lift the gate open and up above the dump body.

A standard dump truck has one front axle, and one or more rear axles which typically have dual wheels on each side. Common configurations for a standard dump truck include the six wheeler which has one rear axle, the ten wheeler with two rear axles, and the tri-axle with three rear axles. These are mainly found in inner cities and in the deep south.

The short wheelbase of a standard dump truck makes it more maneuverable than the higher capacity semi-trailer dump trucks.

Articulated dump truck

Articulated dump truck or dumper

An articulated dump truck has a hinge between the cab and the dump box, but is distinct from semi trailer trucks in that the cab is a permanent fixture, not a separable vehicle. Steering is accomplished via hydraulic rams that pivot the entire cab, rather than rack and pinion steering on the front axle. This vehicle is highly adaptable to rough terrain. In line with its use in rough terrain longer distances and overly flat surfaces tend to cause driveline troubles, and failures. Articulated trucks are often referred to as the modern scraper, in the sense that they carry a much higher maintenance burden than most trucks. See the first mass produced articulated dump truck (articulated hauler):

Transfer dump truck

Example of a transfer truck and trailer

A transfer dump (colloquially referred to as a "Slam-Bang!" because of the noise made when transferring) is a standard dump truck which pulls a separate trailer which can also be loaded with aggregate (gravel, sand, asphalt, klinker, snow, wood chips, triple mix, etc.)

The second aggregate container, (B box) on the trailer which is powered by either an electric, pneumatic motor or hydraulic line from a PTO (power take off) mounted on the transmission of the tractor, rides on small wheels and rolls on rails off of the trailer frame and into the empty main dump (A) box. The key advantage of this configuration is to maximize payload capacity without sacrificing the maneuverability of the short and nimble standard dump truck. Transfer dumps are typically seen in the western United States because of the peculiar weight restrictions on western highways.

Another configuration seen is called a Triple Transfer Train, which consists of a B and C box. These are common on Nevada and Utah Highways but not in California. Depending on the axle arrangement, a Triple Transfer can haul up to 129,000 with a special permit in certain US states. The Triple Transfer usually costs a contactor about $105 an hour while a A/B config usually runs about $85 per hour (2007 stats).

Truck and pup

A truck and pup is very similar to a transfer dump. It consists of a standard dump truck pulling a dump trailer. The pup trailer, unlike the transfer, has its own hydraulic ram and is capable of self-unloading.

Example of a Pup trailer

Superdump truck

A Superdump is a straight dump truck equipped with a Strong Arm trailing axle, a liftable, load-bearing axle rated as high as 13,000 pounds. Trailing 11 to 13 feet behind the rear tandem, the Strong Arm axle stretches the outer "bridge" measurement—the distance between the first and last axles—to the maximum overall length allowed. This increases the gross weight allowed under the federal bridge formula, which sets standards for truck size and weight. Depending on the vehicle length and axle configuration, Superdumps can be rated as high as 80,000 pounds GVW and carry 26 tons of payload or more. When the truck is empty or ready to offload, the Strong Arm toggles up off the road surface on two hydraulic arms to clear the rear of the vehicle. Strong Arm axles are built by Strong Industries Inc., of Houston, Texas. Truck owners call their Strong Arm-equipped trucks Superdumps because they far exceed the payload, productivity, and return on investment of a conventional dump truck.

The superdump with the Strong arm is said to be safer with the fact that every axle has brakes. They have recently added a new secondary lateral suspension system that has added much more stability to the truck also. They have also added an out of level system if you get a flat tire that will release the pressure on the axle to help with handling even if the tire is low on air it will release the pressure.

Semi trailer end dump truck

End dump trailer.

A semi end dump is a tractor-trailer combination wherein the trailer itself contains the hydraulic hoist. A typical semi end dump has a 3-axle tractor pulling a 2-axle semi-trailer. The key advantage of a semi end dump is rapid unloading. A key disadvantage is that they are very unstable when raised in the dumping position limiting their use in many applications where the dumping location is uneven or off level.

Semi trailer bottom dump truck

Bottom dump trailer.

A semi bottom dump (or "belly dump") is a 3-axle tractor pulling a 2-axle trailer with a clam shell type dump gate in the belly of the trailer. The key advantage of a semi bottom dump is its ability to lay material in a wind row (a linear heap). In addition, a semi bottom dump is maneuverable in reverse, unlike the double and triple trailer configurations described below. These trailers may be found either of the windrow type shown in the photo, or may be of the 'cross spread' type with the gates opening front to rear instead of left and right. The cross spread gates will actually spread gravel fairly evenly the width of the trailer. by comparison, the windrow gates leave a pile in the middle. The cross spreads jam and do not work well with larger materials. Likewise they are not suitable for use where spreading is not desired such as when hot asphalt paving material is being dumped in front of a paving machine.

Double and triple trailer bottom dump truck

Double and triple bottom dumps consist of a 2-axle tractor pulling one single-axle semi-trailer and an additional full trailer (or two full trailers in the case of triples). These dump trucks allow the driver to lay material in wind rows without ever leaving the cab or even stopping the truck. The main disadvantage is the difficulty in backing double and triple units in reverse.

The specific type of dump truck used in any specific country is likely to be closely keyed to the weight and axle limitations of that jurisdiction. Rock, dirt and other types of materials commonly hauled in trucks of this type are quite heavy, and almost any style of truck can be easily overloaded. Because of this, this type of truck is frequently configured to take advantage of local weight limitations so as to maximize the allowed weight. For example, within the United States, a maximum weight limit of 40 tons is mandated throughout the country except for specific bridges that may not be safe with that weight, however, individual states in some instances are allowed to authorize trucks up to 52.5 tons, however, most states that do so, require that the trucks be very long so as to spread the weight out over more distance. It is in this context that you see the double and triple bottoms within the United States.

Side dump truck

A side dump truck consists of a 3-axle tractor pulling a 2-axle semi-trailer. It has hydraulic rams which tilt the dump body onto its side, spilling the material to either the left or right side of the trailer. The key advantages of the side dump are that it allows rapid unloading and can carry more weight in western United States. In addition, it is almost immune to upset (tipping over) while dumping unlike the semi end dumps which are very prone to tipping over. It is, however, highly likely that a side dump trailer will tip over if dumping is stopped prematurely. A disadvantage occurs when dumping lose materials or cobble sized stone, the side dump will often get stuck in its own pile.

Off-road dump truck

Liebherr T 282B mining truck.

Hitachi mining truck.

Off-road dump trucks more closely resemble heavy construction equipment or engineering vehicles than they do highway dump trucks. They are used strictly off-road for mining and heavy dirt hauling jobs.

The term ‘Dump’ Truck is not generally used by the mining industry, or by the manufacturers that build these machines. The more appropriate US term for this strictly off road vehicle is, ‘Haul’ truck. The classification bottom and side for example, describes how the loaded material is discharged once loaded. In the case of the Haul truck illustrated, a Liebherr T 282B the load is discharged to the rear, designating this particular vehicle as an end dump. Bottom dump normally describes a trailer that discharges its load by opening two clam shell doors under the load space, in some examples several trailers (road train) are pulled by one truck mainly these are on road machines. The only remaining example of what is described as a unitized bottom dump coal hauler is manufactured by Kress Corporation. This large capacity truck is used for the transportation of coal from a loading device (shovel) directly to a power station or bulk storage area.

Winter service vehicles

Many winter service vehicle units are based on dump trucks, to allow the placement of ballast to weigh the truck down or to hold salt for spreading on the road.

Dangers

Potentially flying goods must be covered (i.e. using a canvas, straps or a rope) to prevent loose material from flying outside the bed when the truck is moving, and to keep the goods from damaging other vehicles. Also heavier items loaded over the edge of the truck must be secured to prevent them from dropping off the truck in turns, on bad roads or when braking the vehicle.

Trucks are normally built for some amount of off road driving or construction site driving, which means that bumpers are either placed high or not even there because the chassis and height of the drivers seat protects the driver fairly. The disadvantage is that in a collision with a family car, the entire motor section or luggage compartment goes under the truck bumper and only the roof and window section makes mentionable contact to the truck. This means that passengers in the car could be cut off at chest height instead of having minor damage in the lower leg region which would be the part the car is protecting through its design. Several countries have made rules that new trucks should have bumpers approximately 40 cm above ground in order to protect other drivers better. There are also rules about how long the load or construction of the truck can go beyond the rear bumper to prevent cars that rear-end the truck from being cut off. Several pictures on the internet show one such case, a Corvette sticking out 50 cm from the edge of a semi trailer