Engineer goes nuts over Wheelsure!

Fife’s Engineering Director Sandy Brydon is piloting a trial that could further boost Stagecoach’s excellent reputation for safety.

The trial of the innovative new Wheelsure nut-locking device, which stops nuts from loosening, was extended to 29 vehicles after a successful first phase.

Sandy explained: “Wheel loss is a sector-wide issue that we take very seriously and we have been very impressed with the results of the initial trial phase.

“Having discussed the results at our engineering meetings we decided the way forward was to increase the number of vehicles fitted with the product and to extend the trial for a further three months.”

Stagecoach already employs rigorous maintenance procedures, which include regular re-torquing, but Sandy is always looking for additional safety features to supplement these procedures and to ensure absolute safety for his fleet.

He added: “Safety is of paramount importance to me and if the trial continues to go well, I would like to see the device fitted as standard equipment on all heavy vehicles.”

Wheel loss and wheel nut loosening, which are caused by a lack of clamping force, are problems that have existed within the transport industry for decades.

The widely accepted view in the industry is that a strict torquing regime will ensure that the correct clamping force is applied to wheel nuts.

However, this belief is not correct. The amount of torque energy applied to a wheel nut does not necessarily translate into the required clamping force to secure a wheel.
Over 90% of torque energy is used up in overcoming frictional resistance in the stud threads and bearing surfaces. Whilst this is still enough to generate sufficient clamping force on a brand new wheel stud, it rapidly becomes insufficient for reused, damaged or incorrectly fitted studs.

This goes a long way towards explaining why wheel nuts still loosen in even the best maintained fleets or only a matter of miles after wheel maintenance has been carried out.

The device, which has been patented and developed by Wheelsure Ltd, recently won Brake’s Vehicle Safety Invention Award. It has a modified wheel stud and counter-threaded locking cap that covers the wheel nut, holding it in place. In the event of the wheel nut starting to loosen, the left hand threaded locking cap immediately tightens against the nut, ensuring that it will not come off.

Independent vibration testing carried out on the device by Bolt Science using a Junkers machine, showed that the device retained the optimum 95% of its clamping force. A 5% loss in clamp force occurs without any nut rotation and is due to embedding loss in the thread and on the bearing faces of the fastener.

The results of this market-leading trial will be known shortly and may well be another example of Stagecoach leading the industry.

On Stage – the newspaper of Stagecoach Group