The IRTE best practice guide on wheel security identifies an issue that operators should be well aware of: that wheel security has been a potentially serious problem for many years. It is a decade now since TRL (Transport Research Laboratory) published the DfT-commissioned report that scoped the problem at 7,500—11,000 CV wheel fixing defects annually. Those, it suggested, result in 150—400 wheel detachments per annum, resulting in 50—134 damage-only incidents, 10—27 serious injury accidents and fatal consequences in between three and seven cases.
Historically, the problem has been mainly due to inadequate wheel inspection, preparation and cleanliness – as well as incorrect nut tightening. Over-tightening causes damage to studs and nuts, while under-tightening leads to insufficient clamping force and nuts that work loose. Correctly set torque wrenches help but, on their own, are not the answer. And while wheel nut accessories – such as Disc-Lock’s safety wheel nut, Checkpoint’s indicator or Ric-Clip’s locking system – help to reveal or prevent nut slackening, correct procedures remain key.
But times and legislation are changing. Transport Engineer reported on the European Roadworthiness Package passing into law in July 2014. As a result, UK legislation comes into force on 7 May 2017 mandating that compatibility be treated as safety critical – meaning hubs and wheels must be correctly matched.
But how can this be guaranteed? MWS Distribution – which originally reported that vehicles fitted with star- or spider-shaped hubs, designed to reduce weight, were seeing cracking around wheel securing holes – has a convincing answer. That problem was due to the lack of conventional hubs’ circumferential fittings, meaning wheels sustaining forces beyond design limits at the contact points. But other issues concern wheel load ratings: technicians replacing wheels at the roadside during wet, cold nights may not be checking replacement wheel ratings as carefully as they might.
MWSD’s solution is about getting procurement and supply right before technicians even pick up their torque wrenches – and ATS Euromaster is an early adopter. “We supply the right wheels in their system,” states MWSD managing director John Ellis, explaining that this prevents its 300-plus depots from sourcing wheels off piste.
“Now they have a procurement process and we supply them with their part numbers, so managers have control, compliance and a complete audit trail. Goodyear Dunlop TruckForce ... are now running the same sort of thing. Some of the big bus companies are also using this process.” And Ellis adds that MWSD is now rolling out its process across Europe.
He also states that, with wheel manufacturers concerned about the lack of information on wheel replacements from the aftermarket, moves are afoot to “feed information back to each other, so that the aftermarket understands these problems”. Wheels already carry load rating information, as do tyres. But this approach adds another dimension – ensuring the correct matching of wheels and hubs wherever and whenever there is a need to change a wheel.