Multi-piece rim wheels

Ground Warrior, August, 2008 by Cynthia Young

Servicing of multi-piece rim wheels is dangerous. Inflating the tires in cages and inspecting the lock rings is very important to ensure personnel safety. The tire cages are mandatory to prevent injury, due to an explosion that might occur while inflating the tire. The lock rings will pop off if they are warped or not put on the rim properly. Lock rings keep the rims in place, and once they do, they can fly in any direction. Four Marines were performing 2nd Echelon Maintenance on a LVS tire, when the locking ring flange shot off the rim injuring two of them. It broke one Marine's hand and fractured bones in one's head. Both experienced abrasions and scratches on their faces.

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A multi-piece rim is a vehicle wheel consisting of two or more parts, one of which has a side or locking ring designed to hold the wheel by interlocking components when the tire is inflated. It is also known to many as a Split-Rim; however, this is not the proper term because the rims now have multiple pieces. It is usually a tube-type tire. Multi-piece rims are normally found on MTVRs, LAVs, forklifts, LVS, TRAMS, HMMWVs, and most heavy-duty tractors, dump trucks, and off road machines. When servicing these rims/tires, you should ensure the tires are deflated before de-mounting and never inflate them outside a cage or barrier. A Corporal sat on the floor inflating the tire on a forklift and the locking ring flew off and struck him in the arm and leg. It broke his arm, but he could have been more seriously injured because of his location to the explosion. A Sergeant was hit in the leg when split ring flew off the tire he was inflating outside of a cage. He was hospitalized and lost time away from work. Training Manuals (TMs) should be available and posted in areas where the wheels are serviced. While operating in the training area, the spare tire should already have the rim installed and the inflation should take place outside the trajectory. Trees may have to be used as barriers. Therefore, employees need to be trained on mounting, inflating, and other hazards associated with multi-piece rim wheels. Marines should make sure the TM procedure is followed. Guidance may be obtained from 29 CFR 1910.177 regarding servicing multi-piece and single piece rim wheels.

If you are using a tire changing machine, the tires should be inflated outside a restraining device only to a minimum pressure sufficient to force the tire bead onto the rim ledge; otherwise, the tire should always be inflated in an OSHA approved cage. After tire inflation, tire and wheel components shall be inspected while they still remain inside the restraining device/ cage to make sure they are properly seated and locked. No attempt shall be made to correct the seating a side and lock rings by hammering, striking, or forcing the components while the tire is pressurized. Deflate the tires completely by removing the valve core to ensure no air pressure remains in the tire. One Marine was struck on the forehead by flying debris when the tire exploded as he removed the wheel bearing with a hammer and socket wrench. Supervisors must ensure the recommended tools in the rim manual, for the type of wheel being serviced, are provided. They should also ensure that those tools are used only to service the rim wheels.

A cage alone is not sufficient protection. Lock rings must also be inspected. Cracked, broken, bent, or damaged rim components shall not be reworked, welded, brazed, or heated. Rim flanges, rim gutters, rings, bead seating surfaces, and the bead areas of tires shall be free of any dirt, surface rust, scale, and loose or flaked rubber prior to mounting and inflation. Lock rings have been known to fly off the rim after the tire has been inflated, because the ring was not assembled correctly or warped. The Air Force experienced two separate serious mishaps where both individuals were struck and seriously injured when rim parts separated. The Army has issued a Hazard Alert on the HEMETT three-piece split rim wheel lock ring NSN 2530-00-278-6567, because some of the rings issued were warped to the extent that the ends of the split ring were offset and not in alignment causing a hazardous condition. When the rims are aligned properly, it could result in the wheel/tire assembly coming apart and the tire exploding after being removed from the cage, due to the amount of pressure when the rims are not aligned. Forty-three percent of our mishaps involving multi-piece rims, occurred when the restraining/lock rings shot off and hit nearby Marines causing injury. These injuries have caused loss of sight, broken arms and legs, and disfigurement.

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Trajectory range is especially important while inflating un-caged tires. A sufficient length of hose between the clip-on chuck and the in-line valve is needed to allow the employee to stand outside of the trajectory. In one of the mishaps, a Marine crimped the hose with his hands to regulate the pressure to the tire and his Supervisor was present. As a result, the rim struck him in the face. He underwent re-constructive surgery and lost vision in one eye, because the seal ruptured.