New materials and technology are beginning to reach the region’s tipper trucks
Tipper truck bodies have remained virtually the same the whole world over since the first serious examples were developed for use on the Hoover Dam back in the 1920s. Now, though, new materials and specifications are being introduced to cope with the weight, punishment and abrasion that hauling rocks, sand and gravel can inflict. Both roadgoing and non-road trucks suffer from the same problems – wear, damage and carry back.
All of which add up to a loss of productivity and profit.
A firm building truck bodies in Dubai has received an order specifying a modern and extremely hard material as the main component.
Jebel Ali-based Gorica is building the trailers for a client who found that regular steel bodies wore out too quickly when tipping gravel over three shifts per day.
The material is known as ‘Hardox’, and it may be most familiar to PMV readers as one of the special hardened metals used in bucket tips and the like.
However, now it is being used to make complete bodies in what is thought to be a first for the country.
Gorica’s Paul Austin Price said; “There’s no other tipper manufacturer in the UAE who is using Hardox at the moment”. In KSA the material is distributed by Shahab and Sons Co.
“As soon as they are finished, they are gone., they are not for use in Dubai as they are too small. Here’s an indication of what they use it for – Sand and building materials are very abrasive – even digger buckets can wear out.”
Hardox
At SSAB, the steelmill where Hardox is made, another experimental dump truck body has been developed.
SSAB’s prototype body for an articulated dump truck is made of Hardox 450. The U-shaped free hanging dumper body design weighs just half as much as a traditional body. The new design takes maximum advantage of the properties of the steel for a more wear-resistant and impact resistant product.
“For end customers the design offers an increased load capacity and lower weight when empty, lower fuel consumption, and fewer and shorter maintenance breaks. The new design also offers advantages to manufacturers, such as shorter production time and simpler, less expensive production process,” says Per-Olof Stark, Vice President Marketing, Sales and Product Development SSAB Plate.
SSAB’s prototype has been tested since 2008 in a road construction project on the E18 highway outside Enköping, Sweden. The dumper body has been in operation for a total of 820 hours and transported over 86,000 tonnes of rock.
“The trial results show that load capacity increased by about 9 percent, providing increased revenue for the contractor. The reduced weight also results in less wear on the engine and drive trains,” says Hans Konradsson, Manager of Market Projects at SSAB Plate.
“During the spring we visited some of the major manufacturers of dumpers and presented our new design concept. We received many favorable reactions,” says Stark.
Making bodies that tip out of harder material is one way of holding back wear, but Caterpillar has come up with an entirely different concept: simply make the ejector system differently, so that the load is pushed out, rather than lifting the back. Of course these are for non-road trucks, but the firm is now offering some ADTs as a chassis-only option, leaving the customer free to chose any type of body required.
Ejector
The new body can be found on the 730 Ejector articulated truck, which incorporates the self-cleaning ejector mechanism that allows material to be spread and dumped on the move without lifting the body.
Because the body is not raised, the ejector truck can work efficiently on sites. As such, the truck can work on sites where stability issues or overhead obstacles limit the the use of conventional dump trucks.
The ejector body also offers clean load ejection to eliminate production-robbing carry-back, where material is not fully ejected from the truck.
The load ejection concept delivers many benefits. Material can be spread while the truck is moving to cut cycle time, decrease power train loads and reduce the amount of support equipment needed for spreading and dozing. The ejector also prevents material from adhering to the inside of the truck body after the dump, so payload can be maximised, improving productivity, reducing fuel consumption and lowering cost per tonne.
Ejecting a load without raising the body increases stability, so the truck can work on inclines, side slopes and in very soft underfoot. The truck is also useful in tunneling and underground applications and on sites where overhead obstacles, such as conveyors, power lines or bridges, interfere with dumping.
The reinforced ejector body is made from high-yield, heat-treated steel. Its top rails incorporate the same steel used on the Cat 769D off-highway truck. The ejector mechanism includes a high-strength blade and technology similar to that proven on Cat wheel tractor-scrapers. The ejector body is designed to work with small rocks though (up to 150mm diameter), so such a thing would not be suitable for applications like offshore projects, where moving bigger rocks is required.
Aluminum
There are other projects from other manufacturers in the pipeline, too. One technical research paper suggests a design concept where even the largest non-road mining truck body could be made from aluminum.
This might sound ridiculous, as we all know that this material is just too soft for such use, but the academic study provides results of a field service history with developments in various designs.
The study, found on mining website onemine.org argues that aluminum truck bodies are not the novelty they might seem. Mention is made of current U.S. usage and predictions given as to future development of aluminum bodies in the mining industry. The paper notes that way back in 1932 an aluminum unit proved very satisfactory in service on the Hoover Dam project but at that time the only high strength aluminum alloys available were not weldable and with the high cost of construction, a sound economic case for an aluminum body could not be made.
After World War II, great advances in aluminum welding techniques, using the inert gas shield, combined with the development of high strength alloys with good welded properties and welding characteristics changed the whole picture. Welded aluminum bodies were rapidly developed and by 1958 attention was again focused on the use of aluminum for off-highway truck bodies.
The paper goes on to explain how a Canadian firm, Alcan, embarked on an extensive development programme to prove the durability and economics of aluminum truck bodies for the mining and construction industries. The first step was to design a prototype aluminum body which took particular advantage of the fact that the ‘modulus’ of aluminum is only one third that of steel.
A body was built and mounted on a 22-tonne truck . Very little information was available as to the order of stresses that were set up in off-highway truck bodies and so it was therefore decided to carry out more tests, which the paper looks at in detail – arguing that this material is lighter, cheaper and more durable than anything else. Time will tell is this analysis is correct.
Tipper bodies make up a good number of the specialist trailers on the road, but one look along any busy highway will show that there are many other types working in the region. One body style particularly in demand at the moment is tankers. Mostly these are carrying either fresh water… or the exact opposite.
However, some are developed for new and different applications. Gorica, for example, has just completed an order for some flour tankers. Remember – flour can be explosive, so care had to be taken in the design. “We had some problems that took us a while to get right, but we did, and the customer is extremely happy “ a manager at the fim said.