Careful attention to haul truck tire inspection and maintenance can prevent catastrophic tire failures.
As part of an overall commitment to safety, quarries need to take a proactive approach to haul truck tire inspection and care. Truck tires are subject to tremendous stresses due to heat, sidewall flexing, torque loads, and, of course, the heavy loads carried by the trucks from the face to the crusher. Rocks on the haul road can easily cause sidewall or face cuts that can lead to catastrophic tire failures — which can endanger ground personnel, cause problems with controlling the truck, and may result in hours of unplanned downtime and lost production.
To help ensure the safety of everyone in the quarry and maintain productivity, a proactive program of tire inspection and care is a must. Prior to operating a haul truck, operators should inspect each tire and check the tread for missing chunks of rubber or embedded objects. They should also check tire sidewalls for any cuts or gouges.
In 2010, the root cause of 4 fatalities in stone surface and milling operations was attributed to powered haulage.
In particular, front tires should be inspected to ensure they are in excellent condition, because they are used to control the truck. The rear of the truck has dual tires on each side; if one of them fails, the operator can still drive the truck back to the shop for maintenance. If one of the front tires fails, however, there is no backup. For this reason, quarries and mines usually rotate tires to the rear of the truck after they are worn 30 to 50 percent, and a new set of tires is placed on the front of the truck.
The haul truck operator must take responsibility to ensure that the tires of his or her haul truck are always properly inflated. Tires can only deliver optimum performance when they are properly inflated; low pressure will cause them to be more susceptible to damage. A bulge at the base of the tire usually indicates low tire pressure.
Proper tire care leads to increased safety and profits
Considering the high cost of haul truck tires today, launching a training program to extend their life is like money in the bank — it goes straight to the bottom line as cost savings. Following are some of the most common threats to haul truck tires and some practical operator strategies that may extend their life.
Haul truck driver responsibilities
The operator of a haul truck is the person most responsible for tire care and safety. Here are some of the most common tire hazards that haul truck operators may encounter and how to avoid them:
Berms: Avoid contact with berms and steep bank faces, which can place excessive stresses on tire sidewalls and may hide other threats, such as embedded rocks or pieces of steel.
Tire flexing: Keep a careful watch for washboard sections of the haul road, which can cause a significant amount of tire flexing. On a fully-loaded haul truck, this flexing can seriously damage tires. Most often, this type of damage is not immediately noticeable. Rather, it is cumulative and may result in sudden tire failure. Slow down on rough sections of haul road to reduce tire wear and stress.
Rocks and spillage: Material in the road must not be ignored, but rather be dealt with immediately. Shot rock can often have sharp edges that can slice through the tread or sidewall of the tire. Go around the hazard, and call the dispatcher or the operator of a nearby piece of support equipment to have it removed at once.
Dump pocket hazards: Haul truck operators must do everything they can to avoid making direct contact with concrete bumper blocks at the back of dump pockets. These back stops can severely shorten tire life. When backing up to a crusher, make sure there is no spillage in the pocket that the truck will either back over or sit directly upon while dumping its load.