Compared with some of the giant trailer production facilities on the Continent, British trailer makers operate on a somewhat smaller scale. So when it comes to safety and durability testing are they at a disadvantage?
Not a bit of it, contends Richard Owens, Group Marketing Manager at Don-Bur.
“We tailor our trailers to the specific needs of each of our customers so all of our products are different,” he says. “For example, we carry out a lot of finite element analysis using an engineering software programme from SolidWorks.
“A while ago we had a problem with the rear frame of our box-bodied trailers,” he continues. “Cracks were occurring between the top header and the side posts but we were able to deal with them by using the programme to detect the stress points.
“Once we had done so we were able to resolve the difficulty by fitting a reinforcing piece known as a ‘boomerang’ that sits next to the marker lights,” Owens says. “We can carry out stress analyses on entire chassis too and we’ve done so on bulkheads as well.”
Don-Bur has also tested trailers in line with the requirements of EN12642-XL, which indicates the ability of the superstructure to retain loads, a particularly important consideration where curtainsiders are concerned.
The curtains cannot be considered as part of a trailer’s load restraint system unless they meet EN’s criteria. If it has been complied with then the trailer should be marked accordingly and supplied with a certificate.
“We’ve carried out static EN tests which involve putting some very large airbags in the trailer, then blowing them up to see how far the curtains billow out,” Owens continues. The airbags are attached to hefty steel frames and a load is applied to the front and rear of the trailer, too.
Don-Bur has also conducted dynamic tests in line with the same standard. “They involve an acceleration test, a deceleration test and taking the laden trailer through S-bends and around roundabouts,” Owens explains.
Fellow UK-based trailer maker SDC also carries out dynamic testing, according to Director Paul Bratton. “We put a curtainsider with folding alloy curtains, a step-frame double-deck trailer and a standard curtainsider through a dynamic testing programme at Alconbury airfield in Cambridgeshire and they all passed,” he reports.
Such tests need to be observed by an independent body to be acknowledged as valid, and Germany’s TUV Nord is frequently involved.
Bibby Distribution is one firm that has acquired Don-Bur curtainsiders that meet EN12642-XL. Passing the test involved subjecting a trailer to a strain of 11.6 tonnes to the sides, 14.5 tonnes to the front bulkhead and 8.7 tonnes to the rear closure.
Other manufacturers that have tested to EN12642-XL include Cartwright and Lawrence David, with the latter stating that it was the first company to have a pillar-less curtainsider accredited to the standard. Cartwright now has a large pool of compliant trailers within its 5,000-plus rental fleet.
The EN standard is not a legal requirement at present but compliance helps future-proof a manufacturer’s products, says Bratton.
“Bear in mind though that there are European markets where operators may find their trailers will not be loaded if they do not have it,” he warns. Companies in the chemical and paper industries, among others, have for some time been insisting that trailers carrying their products must be tested to the standard.
Enforcement officers in mainland Europe may be more likely to stop and check trailers if they do not bear an EN logo, trailer manufacturers believe. Perhaps not surprisingly, European trailer builders have embraced the standard with alacrity, with Kogel stressing that the latest version of its FlexiUse curtainsider displayed at the recent IAA Hanover Commercial Vehicle Show in Germany complies fully.
European Community Whole Vehicle Type Approval has had little impact on trailer durability either way Owens contends. “That’s because it does not really address structural strength,” he observes.
Testing is often no substitute for real-world experience. Relying heavily on customer feedback and its own industry knowledge, Don-Bur carefully examines the uses to which trailers and bodies are being put and engineers them accordingly.
“For example, we fit spreader plates to the cross-beams of drays to dissipate the repeated impact of beer barrels being loaded and unloaded,” Owens says. “We know too that the stresses on trailer necks and landing legs imposed by the construction industry are more arduous than those imposed by general haulage so they have to be beefed up accordingly.”
Real-world experience has been especially important when it comes to assessing the fuel economy benefits afforded by the aerodynamic and distinctively-styled teardrop trailer, says Owens, because the uses to which it is put can vary so much.
“We’ve done some simulated wind tunnel testing and test track testing, too, but when it comes to fuel economy figures we quote an average taken from a cross-section of operators,” he says.
Whatever the weather can throw at the trailer, the operators can rest assured that they have purchased products that are safe and durable, thanks to the high standards of testing they have received.