Caravan broken wheel stud warning
Accidents caused by loose wheel nuts and broken wheel studs are preventable, industry expert warnsThe Caravan Council of Australia is warning caravanners to check that their caravan wheel assemblies are up to scratch, to help prevent an accident or injury caused by a broken wheel stud or loose wheel nut.
"The CCA continually receives reports of broken wheel studs, and loose wheel nuts, sometimes with the nuts unwinding completely off the studs," the CCA's Colin Young explained.
"It must be stressed that if a stud breaks, it is certainly no proof that the stud itself was faulty. There are a number of reasons for the problems."
Young advised that owners and installers should carefully follow any supplied instructions regarding wheels and wheel nuts, and ensure any aftermarket wheels and nuts fitted are "completely suitable for the vehicle and axles".
He outlined some possible reasons for broken wheel studs or loose nuts, including when the pitch circle of the studs in the (imperial) hub don't line up exactly with the holes in some (metric) wheels, so the studs bend when the nuts are tightened, or when the angle of the taper on the nuts doesn't match the angle of taper in the wheels.
Young also pointed the finger at the use of low-grade steel studs, and when the hole in the wheel centre is not compatible with the spigot diameter of the hub.
Also potentially problematic is when serrated studs are not “fully driven home” when pressed into the hubs, so that they gradually “give a little” and cause the nuts to loosen.
He warned rattle-guns set at unknown high-torque levels and used to tighten wheel nuts (rather than just undo them), can cause the studs to stretch and become weakened.
Also raising alarm bells is when wheel nuts are tightened in a circular pattern in one action, rather than in a criss-cross pattern using two or three (increasing) torques, while it's possible that 'highly dished' wheel centres can act as large 'spring-washers' that gradually lose tension and cause the nuts to come off.
"Clearly, all nuts must be tightened to the correct torque, and in the correct pattern, in strict accordance with the instructions provided by the wheel or chassis manufacturer," Young said.
"It is strongly recommended that pencil lines are made on one face of each nut (with a mating line on the wheel) so that a quick visual inspection can detect any loosening of a nut.
"Clip-on plastic 'indicators' fitted to each nut, with their adjacent 'arrow-heads' aligned, provide an even-quicker warning of any nut loosening.
Travelling on dirt roads and corrugations without lowering tyre pressures and without shock absorbers fitted can also exacerbate any issues.
"Continual vibrations and occasional heavy impacts from road surfaces, inevitably have an adverse effect on the wheel assemblies," he said.
"This is severely aggravated if the tyre pressures and the spring rates are too high for the actual wheel-loading.
"Stresses on the wheel assemblies are further increased if shock-absorbers (dampers) are not fitted.
"Leaf springs do provide some damping of vibrations, but unfortunately it is mainly on the bump' (upwards) movement of the wheel, rather than on the 'rebound' (downwards) movement… where it would be far more beneficial".
Related reading:
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