Dump Trucks

What is Dump Truck ?

A dump truck (dumper truck) is a truck used for transporting loose material (such as sand, gravel, or dirt) for construction. A typical dump truck is equipped with a hydraulically operated open-box bed hinged at the rear, the front of which can be lifted up to allow the contents to be deposited on the ground behind the truck at the site of delivery. In the UK and Australia the term applies to off-road construction plant only, and the road vehicle is known as a tipper, tipper lorry or tip truck.

Types of Dump Truck

 

A standard dump truck is a truck chassis with a dump body mounted to the frame. The bed is raised by a hydraulic ram mounted under the front of the dumper body between the frames, and the back of the bed is hinged at the back to the truck. 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.

Common configurations for a standard dump truck include the six wheeler which has one powered rear axle, the ten wheeler with two powered rear axles, the tri-axle with one lift axle and two powered axles, and the quad with two lift axles and two powered axles.. The largest of the standard dump trucks is commonly called a "centipede" and has seven axles. The rear two axles are powered, the front axle is the steering axle, and the remaining four are lift axles. The intermediate axles are present to support the weigh over the length of the chassis and sometimes to provide additional braking power. In the European Union, the dump truck configurations are 2, 3 and 4 axles. The 4 axle eight wheeler has 2 axles at the front and 2 at the rear and is limited to 32 tonnes gross weight in most EU countries

An articulated dump truck, or "Yuke" in the construction world, 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).

A transfer dump is a standard dump truck which pulls a separate trailer which can also be loaded with aggregate (gravel, sand, asphalt, klinkers, snow, wood chips, triple mix, etc.) The second aggregate container, (B box) on the trailer, is powered by either an electric, pneumatic motor or hydraulic line. It rolls on small wheels, riding on rails from the trailer's frame, into the empty main dump (A) box. This maximizes payload capacity without sacrificing the maneuverability of the 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 kilograms with a special permit in certain US states. The Triple Transfer usually costs a contractor about $105 an hour while a A/B config usually runs about $85 per hour (2007 stats). Transfer dump trucks typically haul between 26 and 27 tons of aggregate per load, each truck is capable of 3-5 loads per day, generally speaking.

Off-road dump trucks more closely resemble heavy construction equipment or engineering vehicles than they do highway dump trucks. Off-road 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'. The classifications bottom and side for example, describes how loaded material is discharged from the dump body. 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 instances, one tractor may pull several trailers (road train). They are manufactured by Kador Engineering, Kress Corporation, Maxter-Atlas and Rimpull. 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.

The current largest off road haul trucks are the Liebherr T 282B, the Bucyrus MT6300AC and the Caterpillar 797F, which each have payload capacities of up to 400 short tons (363 t). Most 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 in this class because it employs a diesel engine to power a mechanical powertrain typical of most road going vehicles. Other major manufacturers of haul trucks include Hitachi, Komatsu, DAC, Terex and Belaz.

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