Oh what a fabulous body!

Transporters are well aware of how the right trailer, tanker or truck body can add value to an operator’s business. STUART MOIR discovers that a truck isn’t up to much without the trailer it’s pulling.

In their quest to build an effective trailer body that can withstand a tremendous amount of abuse during its lifetime, designers and fabricators have used a variety of ferrous and non-ferrous metals to construct bodies that are strong and hardwearing, while at the same time as light as possible. In so doing, they have learnt a great deal about metals and their characteristics. As Nico van der Westhuizen, technical engineer at Swedish steel manufacturer, SSAB, explains: “The challenge is finding materials that display all the necessary attributes without affecting quality or customer satisfaction.” By way of example, during the last 20 years the innovative application of aluminium in bulk transport equipment has made it possible for designers to reduce weight without compromising strength.

“The design of a trailer can make a huge difference for the customer in securing a deal. If the trailer is lighter, the payload will be more and the customer will be able to lower the transport cost per load. The transport market is still very focused on payload; but with roads in South Africa getting worse, it is difficult to supply trailers that are light weight and yet robust enough for the conditions in which they need to operate,” says Leon van de Wetering, marketing manager for Afrit. In his view, the only benefit to using aluminium is weight saving, and this is trailer-specific.

Yet managing director of Duncanmec, John Rivett-Carnac, sees aluminium as an extrememly versatile material. “Aluminium is more expensive, but the returns are ongoing for the life of the body because the vehicle can deliver bigger payloads consistently.” In addition, Rivett-Carnac sees aluminium as a beautiful material: “It’s stunning to use and it doesn’t rust, so it’s a lot more resilient,” he says.

Duncanmec’s double tipper is a good example of this. “Traditionally, most side tippers and sliders have been constructed of steel, which is perceived to be stronger,” says James Trace, manufacturing director. “We have been manufacturing aluminium end tippers for years and have proved that they are not only lighter than traditional tippers, but also strong and durable.”

Rivett-Carnac elaborates: “Our aluminium double tipper has the capacity to significantly increase payload capabilities whilst providing the market with an alternative to current tippers. On average, aluminium is between 1.5 and two tons lighter,  allowing for extra payload and increased profit.” However, he acknowledges that Duncanmec also use steel in constructing their bodies. “Welding aluminium requires special techniques and better-skilled workers. And a lot of people in the industry still prefer steel, so we need to cater for them until they see the full capabilities of aluminium,” he explains.

Aluminium isn’t the only high strength metal that has been developed over the years. Van der Westhuizen notes that other high-strength steels have had a profound impact on tipper design. “An ever-increasing number of manufacturers around the world have introduced high-strength steel tippers that are far superior to tippers made of traditional materials,” he maintains. “By using advanced high-strength steel for vital parts of both the chassis and the tipper body itself, manufacturers can produce tippers with a number of advantages that improve their competitiveness. The main advantage is, of course, lower weight. Advanced high-strength steels enable thickness to be reduced without sacrificing strength.”

Afrit’s Van de Wetering elaborates: “We use aluminium only on flat deck trailers and moving floor trailers. But on the flat decks you are limited if you go the aluminium route: the load needs to be evenly distributed over the full deck length and width, which means you can’t carry point loads, whereas on a steel trailer you can. But on an aluminium link you will get a weight saving of approximately 800 kg.” He also agrees with Rivett-Carnac regarding weight savings, “On the moving floor you get a weight saving of approximately 1.5 to two tons per trailer. But an aluminium moving floor is not suitable for transporting highly abrasive products. In the moving floor trailer, the floor itself is also aluminium and therefore also limited. Should a customer want to transport abrasive products we will offer a side tipper and not a moving floor.”

Rivett-Carnac believes that as aluminium design and application develops, structure and versatility will improve. But as Van der Westhuizen explains, the application of other steels is also improving. “Domex is a range of high strength steels from Swedish steel manufacturer SSAB, developed to provide companies in the heavy transport industry with lower-weight steel that is stronger. Domex steel also offers the environmental advantages of reduced dead weight, increased payloads, and a longer life than traditional steel. This helps you cut costs and produce more attractive products,” he says.

These improvements have seen the elimination of reinforcements on tipper sides and other parts. “This results in a much simpler production process: fewer parts, and less welding and joining are needed. At the same time, a new, more streamlined design with smooth surfaces reduces drag and lowers fuel consumption. The most obvious use of advanced high-strength steel is for the chassis and tipper body; but great savings are also possible in other parts, such as the landing gear, under run protections and suspension,” Van der Westhuizen continues.

According to Van de Wetering, modern trailer body designs incorporate additional internal frames to enhance panel stiffness, and are conceived in such a manner that – in the event of damage – they can be repaired in sections without compromising structural integrity.

Beyond steel and aluminium, Van de Wetering says that Afrit has introduced something different since entering the refrigerated truck market in 2008. “We make use of Composit: a material completely different to that used by our competitors. Composit is very strong, and is currently used in the manufacturing of specific parts for aircraft, boats, missiles and more. This light-weight material improves payload – vitally important for fridge trailers because of the difference loading an extra pallet can make.”

As Van de Wetering explains, trailer body weight management is essential. “We make use of computer programmes to help us determine what is needed in the design to ensure that the trailer is strong enough for the specific loads to be transported. Should the trailer not be manufactured strong enough for its load, it could collapse and cause a major accident. Another safety factor is the braking system; ABS or EBS are now  standard requirements incorporated into the design of various trailer bodies.”

According to Van de Wetering, safety aspects are taken into account in manufacturing all Afrit’s standard products. “These trailers can be hooked behind almost any kind of truck,” he says. “But we also manufacture special orders with a specific truck in mind. A truck’s tare also plays a big role, although customers often prefer a specific truck and don’t seem to care about the weight. Gross vehicle mass (GVM) is also important, because you need to purchase a truck that is strong enough to do the job.”

Rivett-Carnac agrees. “The weight of the truck is a major factor when considering which body to use. Often people buy trucks that are too light for the load they are required to pull – so they break. A truck that works well in Europe may not run at its best here because of different operating conditions and higher speeds.”