In the past seven months we have received three bus incident notifications relating to dislodged wheels.
Bus operators have reported that while their bus was in operation the dual wheels have completely dislodged from the left hand side of the drive axle. In all instances the driver was not aware of any problem until a vibration was felt, followed shortly after by a thumping sound as the dislodged wheels struck the under body of the bus.
We have investigated each incident. However, it has not been possible to conclusively identify the cause. We recommend that bus operators review their pre-trip inspection process and consider the use of engineering controls to reduce the risk of wheel nuts loosening. The following wheel nut management systems may be of assistance:
- Wheel nut indicators – provide a visual indication for a wheel nut that has loosened
- Wheel nut link retainers – link wheel nuts together reducing the risk of a wheel nut loosening.
For further information about this matter, and/or bus legislative requirements in Victoria, please contact Andrew Chlebica, Manager Compliance and Information, on (03) 9655 6873. This advice is effective immediately.
Approved by Stephen Turner – Director, Bus Safety. 11 April 2013