strapped
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for strength
The depressing news is that only a third of the straps put through our test cycle met their claimed breaking strain. While even that is some improvement on our last test, its a sad conunemary on the apparent inability of some restraint strap manufacturers to produce products that measure up to the claims made for them.
This year we asked a Scottish truck dealer to order by phone three sets of straps from each of 11 manufacturers selected at random (one more than last time ) on our behalf. The dealer then had all the straps dispatched to the NEL, an independent organisation whose laboratories carry out testing for both the public and private sectors. We tested three examples of each strap so that our results would not be based on a single strap.
Transport locks
All the straps were rated at five tonnes, 10m long, 50mm wide and equipped with claw hooks. Two of them were fitted with transport locks, although these were not specified in the order.
The test procedure followed was exactly the same as last time and, as then, was witnessed by Bernard Maynard-Smith, the chairman the Association of Load Restraint Equipment Manufacturers. The organisation was formerly known as the Association of Webbing Load Restraint Equipment Manufacturers but changed its name to encompass producers of chains, ropes, cargo area load securing tracking and load area shoring poles Each of the straps was shortened to a length of 2.1m between the hooks and attached to the test rig. A double-acting hydraulic ram was then used to tension them at a rate of 20thilm a minute.
The tests were conducted in line with British Standard fi.S5759: 1987, but did not include a drop test.
Before putting each strap on to the test rig we made 1.25 turns of the ratchet spreader bars once the webbing had been threaded; this is the minimum number of turns which are likely to be made in normal service.
Each strap was tensioned to its failure point. The test moni toring equipment recorded the load on the strap at the time it gave up the struggle and the maximum force exerted (in kilo Newtons).
Eleven of the 33 straps reached and
exceeded rive tonnes but only in one case did all three straps from a single manufacturer make the grade. The manufacturer in question is Tony Beal of Ballieston, Glasg-ow (an ALREM member) and the company should be congratulated on its performance. Our only criticism of Beals straps was that one had a faulty label with the manufacturer's name and address missing.
Substandard hook
One or two other straps came close to reaching five tonnes, but one failed at less than four tonnes when a claw hook opened out; a dismal performance. We can only conclude that a substandard hook had somehow found its way into the parts store of the company concerned and been fitted inadvertently.
The other claw hook failures occurred once five tonnes had been exceeded, which would suggest that most manufacturers in our sample are using hooks of reasonable quality It should low
1 be born in mind that virtually all straps are assembled from bought-in parts: Maynard. Smith estimates that there are only four hook, three buckle, and two webbing suppliers active in the UK.
More attention needs to be paid to webbing quality and stitching patterns and quality varied markedly It's interesting to note that some companies—Davco, for example—are using a random stitching pattern. The idea is that this is less likely to be chafed through over time by a side rave.
There were two or three instances of the webbing slipping half a turn or so on the buckle before failure took place. The buckles used by Bridon in particular gave us some cause for concern because the plating on them was pitted. On the positive side, however, we cannot but approve of buckles with transport locks as fitted by Apex and Spanset. They're a sensible extra safeguard against the buckle opening while the cargo secured by the the strap is in transit.
Breaking strains ranged from just 3,822kg to a beefy 5,497kg: a spread of over 1.6 tonnes.
Extra safeguard
As for labelling, the standard seems to be improving, with labels containing more comprehensive data on the manufacturer/supplier; where they can be contacted; and whether they comply with BS5759: 1987. However, two sets of straps had no labels attached to the
fixed or adjustable end. While the performance of load restraint straps seems to be getting better year-by-year, there is still plenty of room for improvement.
To have two-thirds of the straps tested at NEL fail to meet their claimed breaking capacity is still unacceptable. Hauliers rely on the claims made by manufacturers in good faith, and their livelihoods are on the line if a strap failure dumps cargo all over the carriageway.
The result could be a fine of up to £5,000, a licence endorsement (and a possible 12-month ban) for the driver; a deeply-displeased Traffic Commissioner—and a serious risk of hartn to other road users.
E by Steve Banner
ALREM'S view
"The tests were fairly conducted, although you could of course have got different results if 2.5 turns of the spreader bars had been made and the test had been run more quickly. I feel the standard of strap has improved somewhat and ratchet construction in particular seems to have gone up a notch in quality," says Maynard-Smith. "The quality of the end fittings seems to have improved too, with no instances of fractures," he adds. "It was good to see codings stamped on some of them, which aids traceability, and to see that some ratchets were stamped with their rated strength. What's more labelling standards are better than they were in previous years. It was interesting to see a mixture of manual and automatic stitching being used, and the standard of stitching was pretty good."
EC Standard
The proposed European Standard is still under discussion, with implementation at least two years away, says Maynard-Smith. As a consequence ALREM, which has been closely involved in drawing up the Euro document, is devising its own Code of Practice.
This will contain many of the new Standard's proposals as well as other recommendations, possibly including tests for abrasion resistance. "In effect its an upgrade of 855759: 1987, but will include some of the more sensible European ideas," says Maynard-Smith.
The European Standard covers a much broader area than BS5759: 1987, which concentrates on load restraint assemblies used for surface transport. As well as ratchet lashings, it embraces wire, rope, chain, and attachment points
It also reviews the general principles of load restraint, and how best to work out the number and type of restraints needed. "In the UK we've got the Nautical Institute interested in the Standard because it can appreciate the mayhem that can occur if a load comes off a trailer on a cross-Channel ferry," Maynard-Smith observes.
Most straps sold in the UK follow the British Standard and quote a Rated Assembly Strength (RAS). This is usually half the breaking strength, commonly referred to either as the UTS (Ultimate Tensile Strength) or the ULS (Ultimate Loading Strength).
The RAS should be borne in mind when you work out how many straps are required to keep a load in place. You should divide the load by the RAS. If a strap's RAS is 2.5 tonnes, you would need eight to lash down a 20-tonne cargo, placed at intervals of no more than 1.5m along the load's length. BS5759: 1987 does not quote a breaking load for the webbing, but the European Standard will state that it must be three times the RAS, and the webbing will have to have a maximum stretch of 7% at the RAS. The British Standard makes no mention of maximum stretch.
The Euro Standard will oblige ratchet handles to pass a strength test, and the mechanism wiII have to be tested for ease of release and recoil under load. This is necessary because of the Manual Handling Operations Regulations 1992, says Maynard-Smith.
Instructions on using a strap safely will have to be supplied, and it will have to be marked so that the user understands how much force is required to load it to the right working tension. Also, the restraint strap in its entirety will have to pass a 100-loading-cycle test to the RAS to show that no slippage occurs in the system (as happened in one or two instances during this test).
Further information
For further information on ALREM contact chairman Bernard MaynardSmith on 0161-449 9077.
The Department of Transport's Code of Practice, Saf0, of Loads on Vehicles is available through HMSO bookshops for £7.40. HMSO has shops in London, Edinburgh, Belfast, Cardiff, Manchester, Bristol, and Birmingham, or phone 0171 873 9090 for its central ordering service.
Being able to rope and sheet a load properly is a declining art. Among trainers who offer this service is Stuart Kelly of Stuart Kelly Enterprises 1984, who also shows drivers how to chain down cargo correctly. He is based at Oxenholme near Kendal, Cumbria, phone 01539 727467.