WHEELS et TYRES
Page 27
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CAMPAIGN
• A new British Standard
on wheels and fixings is due to be launched next year — and experts hope that money raised by Commercial Motor's , wheel loss campaign will help find the right tiveAlelii standard to solve the cAL ,rtiapt wheel loss mystery. At least £30,000 has been raised for research from the CM campaign and industry donations. The Department of Trade and Industry has pledged to match money raised pound for pound.
Commercial Motor became involved in finding a solution to HGV wheel loss after Stockton-based haulier Cohn Lowe wrote to us just over a year ago. He challenged hauliers — and Commercial Motor — to tackle the problem, after reading in CM that research into wheel loss was being hampered for lack of £30,000.
Lowe, who had witnessed the "terrifying" sight of a tanker shedding a wheel, backed up his challenge with a cheque to start the ball rolling. "Wheel loss happens too often and to too many people," says Lowe, who runs five tractors and 15 trailers on general haulage work. "It could happen to any of us."
Three deaths a year are caused by shed wheels, says the Department of Transport, but other estimates put the toll closer to 10.
COMMISSIONED Don Wright of Sigma Engineering Consultants has been commissioned to write the new British Standard for wheel fixings and to modify the current standard for wheels.
"The objective is to create a new standard on wheel fixings quality," he says. "At the moment many do deteriorate with normal use. When you've changed a wheel a few times tightening the nut can put a lot of friction into the thread between the nut and washer. Sometimes only 20-40% of the original clamping force is generated. Even with the best care, the fixings do deteriorate.
"The standard will define simple tests for wheel and nut manufacturers so they can check the product will perform consistently with repeated service," he explains.
"British Telecom's £10,000 donation (see news story, page 6) means that the researchers will be able to carry out work on the thermal effects on alloy wheels and research on conical fittings," says Wright. This was shelved last summer for lack of
cash. "Alloy wheels are growing in popularity," says Wright. "A lot of heat gets into wheels from the brakes and we want to find any link between temperature and losing an alloy wheel."
Consultant engineer Ivan Ratcliffe has given evidence in court in more than 100 wheel loss cases "and many more which never get to court", he says. "In all cases except two I've dealt with, the problem has been with the nearside rear wheel. Until we alter the design wheel loss won't stop."
If the wheel stud diameter is increased by just 2mm to 24mm, clamping force is boosted by nearly 20%, says Ratcliffe.
Wright agrees: "The one that tends to come off most is the nearside twin driven wheel. With twin wheels, because there are more interfaces clamped together, there's more chance of them chafing loose."
The nearside also suffers more stress, he adds, because of load transfer due to camber, hard cornering at roundabouts and hitting kerbs and drains.
RESEARCH
Research is being carried out at the Motor Industry Research Association this year, and Wright has already begun preliminary work on the British Standard.
Donations to the wheel loss fund have ranged from £5 to £10,000. Some, like Middlesex-based firm Vanguard Engineering, have been victims of wheel loss — "and it could so easily happen again", says Vanguard managing director Mac McCullagh. Wheel loss has struck the fleet twice. In both cases it hit the nearside drive axle of a tractor with right-hand-thread wheel nuts. Now McCullagh would like to see the manufacturers do more — as he says: "It's their truck."
One manufacturer who did get involved is Seddon Atkinson, which hopes the fund will allow research "to concentrate on the problem, which occurs for many different reasons".
David Rae, who owns Bradford-based company James Whitaker, says: "We have a personal axe to grind." One of its artics shed two wheels on an A-road last November. Whitaker was cleared of any negligence and given an absolute discharge by the court.
Harrow and Wealdstone Transport, which moves rock acts, has not suffered any wheel loss from its three HGVs, but that did not stop it from supporting the fund: "It's a case of putting your money where your mouth is. It's something which helps us all."
I I by Gill Harvey