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Off-highway dump truck is a dump truck mainly used in open-pit mines, and its working environment is harsh.
With the expansion of open pit mining scale and the increase of mining depth, most off-highway dump trucks often go uphill continuously with full load and require continuous braking when going downhill. Diesel engines and transmission systems run at full load for a long time (more than 40%).
Therefore, off-highway dump trucks have the following 8 characteristics:
Off-highway dump trucks only run within a limited range of mining areas, so the overall dimensions of the cars are not restricted.
In order to increase the volume of transportation, manufacturers always try to increase the volume of the truck as much as possible, thereby increasing the overall size of the truck. The overall dimensions (length x width x height) of the 797B dump truck produced by Caterpillar is 14.530mx9.761mx7.083m, and the total height after the cargo compartment is raised is 15.292m.
With the development of high-tech centered on microelectronics technology, a large engine that once restricted the large-scale off-highway dump truck has been successfully developed, which has caused tremendous changes in the mechanism of off-highway dump trucks. The load capacity of dump trucks increased tremendously.
Off-highway dump truck engines generally use turbocharging and intercooling technology, and the level of automatic control continues to improve, which greatly improves the engine's power and fuel economy.
There are two types of transmission modes for large off-highway dump trucks: hydraulic mechanical transmission and electric mechanical transmission. Electric mechanical transmission is divided into DC drive system and AC drive system.
The AC drive type electric wheel dump truck adopts AC motor as the traction motor. Compared with the DC electric drive system, the AC electric drive system has the advantages of high reliability, easy maintenance, low maintenance cost, good dynamic delay and high speed.
Compared with electric-driven dump trucks, hydraulic-mechanical-driven dump trucks show better performance on slopes, run faster on flat roads, have good acceleration performance, and adapt to changes in road conditions, while electric-driven dump trucks has low maintenance cost, long working life of engine and transmission system and low fuel consumption.
There are many slopes in the mining area, and the dump truck has a particularly large load capacity. Therefore, the reliability of the braking system needs to be guaranteed first.
The main brakes of dump trucks mainly include drum brakes, caliper disc brakes and oil-cooled disc brakes. Oil-cooled disc brakes have the advantages of small size, simple structure, fast braking response, and stable braking efficiency. But the disadvantage is the heat capacity of brake disc is small, the braking efficiency is low, and the braking force generated by the disc brake under the same size is smaller than the braking force generated by the drum brake.
In addition to the main brake function, off-highway dump trucks also have auxiliary retarding braking capabilities: engine exhaust brake, hydraulic retarder and so on.
When the dump truck goes down a long slope, the retard braking function plays a major role. It reduces the frequency of use of the main brake, prevents the main brake from overheating, and improves the reliability of the dump truck's braking system.
Off-road dump trucks with a load capacity of more than 35t all use oil-gas suspension cylinders. The shape of this type of suspension is most suitable for the installation and use of short-wheelbase but particularly high-weight trucks.
The head space in the cylinder is compressed nitrogen, which plays a role of buffering elasticity; the middle and lower space in the cylinder is filled with hydraulic oil, which plays the role of shock absorption(stopping damping effect), absorbing heat (heating by compression of nitrogen), sealing and lubricating.
For the dump truck that adopts independent suspension, the oil-air suspension cylinder of the front wheel also functions as the steering king pin. The outer cylinder is fastened to the outside of the frame rail, so the traditional integral front axle is omitted.
In order to increase the lifting force and the lifting stability, and facilitate the layout, the off-highway dump trucks often adopt double cylinders to lift.
Two lifting hydraulic cylinders are arranged on the outside of the frame (some are also arranged on the inside). The lifting cylinder is a multi-stage telescopic hydraulic cylinder (generally no more than three stages), which not only reduces the installation length, but also conforms to the feature that the lifting force of the dump truck gradually decreases during the lifting process (the closer the lifting end point, the smaller the lifting cylinder bore).
The frame of the off-highway dump truck adopts a fully welded structure. For models with a load capacity of more than 50t, the longitudinal beams are all closed box-shaped cross-sections, and the tubular beams and longitudinal beams are welded into a whole to ensure high torsional strength. The thick steel plates used are low-alloy, high-strength steel plates.
The tires used in off-highway dump trucks are tubeless pneumatic tires, which have the characteristics of good air tightness, fast heat dissipation, simple structure and long service life.
Tubeless pneumatic tires can be divided into diagonal tires and radial tires according to the cord structure. Radial tires are superior to diagonal tires in terms of ground adhesion, rolling resistance, bearing capacity, and service life.
The choice of tires is mainly based on factors such as the load to be borne, the running road conditions, and the maximum speed.
The above are the 8 characteristics of off-highway dump trucks. I hope this article can help you know more about off-highway dump trucks. If you need to buy an off-highway dump truck, please consult online customer service or leave a message on the website for a professional quotation.
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