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Wheels fell off trailer after over-tightening
Page 32
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THE USE of a bar instead of a torque wrench, when tightening lorry wheel nuts, was a dangerous practice and must be drawn to the attention of those responsible for maintenance, it was said by Penrith magistrates last week.
Jones Transport (Sandbach) Ltd appeared before them charged with using an articulated vehicle when the trailer offside wheel fittings were not properly maintained.
Evidence was given on behalf of the Police, prosecuting, that the vehicle was on M6 when its offside pair of trailer wheels came off and rolled across the central reservation, finishing up on the grass verge. When the vehicle was examined it was found that all 10 securing nuts had sheared off the hubs.
Called for the defence, Mr B. W. Wilkinson, a consultant engineer of Transport Technical Services, Sandbach, produced the 10 studs and one of the two wheel-hubs. He indicated there was no sign of wear on the hub such as would have been caused if the nuts had been loose. Both trailer and hubs were only some three months' old and so far as the studs were concerned nine of the 10 showed a clean break while the 10th had been wrenched off.
In his opinion, said Mr Wilkinson, the failure of nine of the studs resulted from fatigue and was probably caused by over-tightening beyond the recommended torque of 350/ 400 lbft. This could occur when a bar was used for tightening instead of a torque wrench.
Mr J. A. Backhouse, defending, said the trailer belonged to another haulier and was almost new. There would be no indication of the fault from a normal inspection and it would have required specialist testing to find it. The trailer was on long-term lease to a haulage contractor at Sevenoaks and the defendant was not responsible for its maintenance. It was impossible to say when the fatigue occurred but clearly the defendant had not caused it.
Granting the company an absolute discharge, the magistrates asked that it should convey to those responsible for the maintenance that a serious accident could have occurred. They were very concerned that an improper method of nut tightening had been used at some stage.