Fatal accident during maintenance on multipiece vehicle wheel with pneumatic tyres
Most tyre explosions and disintegration of multipiece wheels occur during re-inflation of the tyre and refitting of the wheel. There have been a few occasions where explosions and disintegration actually occur during deflation of the tyre and the removal of the wheel from the vehicle. The following information results from one such event which resulted in the death of a maintenance fitter.
A maintenance fitter was critically injured when removing a multipiece wheel from an industrial lift truck. The vehicle had dual wheels on the front axle fitted with pneumatic tyres with tubes and liners. The dual wheel assembly was fixed to the hub with clamp type bolts
Neither tyre from the dual assembly was deflated prior to the commencement of removal from the vehicle. One or both inner tubes exploded during the latter stages of undoing the clamping bolts, resulting in the wheel assembly striking the deceased.
What do I need to do?
Make sure vehicle and tyre fitters can recognise different wheel constructions and are aware of the risks associated with the different types, that they are properly trained and have the correct equipment available.
Use a safe system of work for multipiece wheel removal
- It is best practice in all situations to deflate pneumatic tyres prior to removing multipiece wheels.
- Alternatively positively establish that the wheel is safe to remove from the vehicle by visually examining it. This means you must check that the flange components are fully and correctly located. Where the flange ring is obscured preventing effective visual examination, for example on dual wheel assemblies, the system of work should always require deflation of the pneumatic tyres before wheel removal. If there is any doubt deflate the tyre first.
Check and Maintain Rims, Wheel Components & Tyres
Ensure that multipiece wheels with pneumatic tyres are maintained in an efficient state and are in good working order.
- The condition of wheels and tyres should be checked at the 'before use' inspection for defects such as fatigue cracks in the wheel and bulges in the tyre wall.
- Periodically examine the rim of a multipiece wheel and flange components for excessive wear, fatigue cracking, severe corrosion, distortion, deformation, impact damage and other similar defects likely to affect wheel integrity.
- In practice it will not be possible to examine all the wheel and tyre components with the wheel and tyre in place.(eg the internal parts of the wheel and flange mating surfaces). The most effective time to examine the wheel and its components is when the wheel has been removed from the vehicle and the tyre removed from the rim (ie when fitting a new tyre).
- The person carrying out the examination should be competent to examine the type of wheel in question.
If safety critical defects are identified the wheel/tyre should be withdrawn from use. You should not attempt to repair a wheel as repairs to wheels and their components can affect the strength and integrity of the assembly. It is recommended that you refer back to the original manufacturers when considering any wheel repairs.
Use a safe system of work for re-inflation of Pneumatic Tyres
Inflating pneumatic tyres can be dangerous.
- Persons carrying out tyre inflation should be adequately trained and competent in working with 'specialist wheels'
- Initially, the tyre should be inflated to a maximum of 15psi, so that you can check that the bead and the loose components have been properly seated. Only once this is confirmed should higher pressures be applied.
- Suitable control measures (at all inflation pressures) including a pressure regulator and pressure gauge to prevent over pressure, an airline of at least 2 metres in length to remove the operator from the likely trajectory area in case of explosion, and providing a purpose built tyre enclosure (normally a safety cage) to contain any violent explosion blast
- You should never leave a tyre during the inflation procedure and by listening for potential problems (eg a 'zipper' failure) you may avoid an explosion
Other Wheel Types
There are other types of wheels fitted to industrial vehicles (eg split wheels (also known as divided wheels), drop centre rims) Tyres fitted to split wheels should always be fully deflated before removal from the vehicle.
Further information on the safety of these other wheel types (as well as multipiece wheels) can be found in Paragraphs 135 to 155 of HSG261 Health and safety in motor vehicle repair and associated industries or in INDG433 Safety during tyre inflation in motor vehicle repair.