Manual (Gravity) tipping Edit
The earliest versions of trailer and lorry mounted dump bodies relied on the principle of gravity for dumping (emptying the load). The very first versions of a dump truck used to haul and dump material was nothing more than a simple dump body style cart drawn by horses. It would have consisted of a two-wheeled cart hinged to the axle with the centre of gravity, when loaded, just behind the axle. The loaded front body was hooked, and when unlatched, would dump. When loaded, the dump body’s centre of gravity would shift, thus it would tend to tip up and discharge the contents or Dump them on the floor. The dump body, when empty, remained locked in a the lowered (horizontal) position. These carts were used in open mines and pulled by horses along a railway track.
After 1900, a four-wheeled horse-drawn flatbed wagon with a rectangular body lifted with a hand operated hoist mechanism at the front was employed. Some of the first trucks with dump bodies designed on this principle appeared as early as 1904 when the Mann gravity dump was built in England.
Early mechanically dumped bodiesEdit
The first mechanical mechanism was the use of a threaded rood (screw) and Nut mounted on the body operated by a hand crank. This allowed less rear overhang and a better weight distribution, to the front axle. This was known as the Bristol dump body raised by a continuous screw in 1905. The first product built by JC Bamford founder of JCB was a simple tipping trailer built from war surplus components, with screw tipping, and the second had a hydraulic tipping mechanism.
Hydraulically operated Dumper bodiesEdit
Hydraulics were being incorporated into truck mounted dump bodies relatively early on (cira 1900). Records show that one of the first hydraulic dump bodies was the Robertson Steam Wagon with a hydraulic hoist that received power from the truck’s engine or an independent steam engine. Alley & McLellan of Glasgow developed another early hydraulic dump body in 1907 that was power-driven by steam.
A conventional dump body is mounted on a truck chassis and has an open body hydraulically operated and hinged at the rear of the truck usually by one or more hydraulic rams that raise the dump budy to unload contents at a delivery site,with off highway trucks rarely have tailgates unless moving saturated sand or sludge that will flow out on an incline.
The hydraulic tipping rams are either front mounted on the head board or underbody mounted and are driven from a gear box power take-off. with hydraulic rams mounted under the body the capability of the body to tip in a three-way basis, either to the left or right side or to the rear is possible by use of four pivot points in place of the usual two.
Dump truck bodies come in various sizes from four-wheelers for two to three tons payload on alight truck chassis to large, heavy-duty articulated and drawbar outfits grossing 30-ton payload capacities for on highway work. The type of dump truck body used will depend on the types of construction or mining material to be carried. For Muck away and demolition waste rugged steel lined bodies are prefered for durability, were as for Coal and grain lightweight "Bulker" bodies are used due to the lower density a much bigger body is required for a given payload.
Off-road Dump TrucksEdit
These modern mammoth sized ( bigger than a house in some cases) dump trucks are “heavy-duty” dump trucks used in open cast mining operations and large-scale earthmoving jobs such as bulk excavation work for cuttings on new roads. In the mining industry, these extra large sized dump trucks are often called “haul” trucks. Loads can be dumped from the side or bottom of the truck in some versions, but usually from the back.
- Early manufacturers
- Euclid builders of the first pure off road dumper.
- Kress and Wabco
- Mack Trucks
- Unit Rig
Articulated Dump TrucksEdit
Articulated Dump Trucks or more usually called just an ADT have a Pivot point (hinge) arrangement between the cab and the rear chassis section/Dump body that was used to steer and on later models allows for twisting by incorporating a vertically mounted rotary bearing. What also makes the articulated dump truck unique is the cab is a permanent fixture and not a separate vehicle (earlier versions used farm tractors fro the power unit with removable trailers fitted with dump bodies. The steering on an articulated dump truck is by hydraulic ram(s) that pivot the complete cab rather than rack-and-pinion steering in the front axle (thus a simpler fixed axle can be used without swivel joints aon
All wheel drive versions). Used mainly on rough terrain applications and able to haul long distances, the articulated dump truck is versatile and has often replaced the motor scraper due to its versatility.
- Off road articulated trucks (ADT's)
- Caterpillar formerly built by DJB / Artix
- DDT Engineering
- Moxy (now Doosan)
- Shawnee Poole
- Volvo BM
- Off-road rigid trucks;
- Autocar Company
- Aveling Barford
- Dart Truck Company
- International Payhauler
- KW-Dart Truck Co.
- Lectra Haul
- Mack Trucks
- WABCO Inc.
- Modern Mine Haulers
- Caterpillar 793 (300 tom ultra class)
- Liebherr TI272 (300 ton ultra class)
- Terex - now own Unit Rig
- Hitachi - now own Euclid
- Komatsu - now own Haulpak
- Road going trucks (UK)
- 500 Years of Earth Moving by Hienz-Herbert Cohrs
- Ultra Haulers (book) by Mike Woof
- Dump Trucks (book) by Donald F. Wood
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