Handling pressurized systems while servicing tyres on single-piece and multi-piece rim wheels presents several hazards.
Rim Wheels - Single-Piece and Multi-Piece
Single-Piece Rim Wheels: Single-piece rim wheels are common on virtually all types of motor vehicles. These wheels allow the use of tubeless tyres, which offer benefits such as reduced rolling resistance and increased mileage. Although tubeless tyres have limitations under severe environmental conditions, they generally pose a lower risk of injury during servicing.
Multi-Piece Rim Wheels: Multi-piece rim wheels are prevalent in heavy vehicles, off-road vehicles, and rubber-tired machinery, which typically use tube-type tyres. These wheels consist of a rim base, side or lock rings, and an inflated tyre assembly. This design is inherently unsafe due to the complexity and potential for misfit components.
General Information When servicing tyres on both single-piece and multi-piece rim wheels, managing the force released by pressurized systems is crucial. For example, a truck tyre with a side wall area of nearly two-thirds of a square metre (approximately 1000 square inches) can release a force of 35 tonnes at 517 kPa (75 psi). This explosive force must be controlled to prevent injuries.
Planning for Safety:
- Determine when the release of force is most likely to occur.
- Identify the equipment needed to control this force and the personnel to operate it.
- Ensure all relevant individuals are aware of the safety procedures for managing this force.
- Regularly check that the necessary equipment, knowledge, and readiness are maintained.
Factors Leading to Misfit and Explosions
Misalignment and subsequent explosions can occur due to:
- Mismatched, distorted, worn, or corroded components.
- Sudden deflation or operation with under-inflated or flat tyres causing rim assembly failure.
Dangers
- Failure to release all air pressure before servicing can result in the valve core being ejected during removal.
- Any pressurized tyre poses a hazard; a sudden release of air can throw a worker against hard surfaces.
- If the air blast is directed against a floor or wall, the wheel rim may be propelled across the workplace.
- Multi-piece rim wheels carry the added risk of components becoming projectiles during an air blast.
Precautions
- Always deflate and inflate tyres in a safety cage or portable restraint device, such as belting restraints.
- Do not reach into the cage during inflation or deflation, and always position your body to one side.
- Avoid placing your head or body in front of the rim during these processes.
- Use recommended tyre mounting tools and equipment to prevent rim damage.
- Wear protective goggles or face shields when working on wheels or tyres.
- Implement a regular tyre maintenance schedule to check for tyre condition, matching, pressure, tread depth, wear patterns, and rim corrosion or cracking.
- Follow recommended tyre servicing procedures and ensure all workers are trained and compliant with these procedures, such as installing the side or lock ring split directly opposite (180 degrees) the valve stem slot.
Summary
By following these guidelines and maintaining a rigorous safety protocol, the hazards associated with servicing single-piece and multi-piece rim wheels can be significantly reduced.