After a decade of helping bang the drum promoting proper torque, it appears the effort has not gone to waste. Most fleets and truck tire service providers fully recognize the importance of tightening fasteners with the correct amount of force. Thousands of torque wrenches have been purchased in the industry, and it looks like they are still being utilized on a daily basis. And in a sign of real progress, many of those wrenches are periodically checked and recalibrated because they are used so often.
With the stakes at an all-time high, trucking companies now refuse to do business with vendors who still subscribe to the old “good-and-tight” method with an impact wrench. A loose tire and wheel on the highway is a 200-lb. runaway wrecking ball that will destroy most things in its path. Since the fastener torque on the offending assembly cannot be determined prior to the accident, most investigators will check the remaining wheels for proper torque. If the vehicle has experienced good-and-tight service, the case against the trucking company will start to build.
Fortunately, research does not indicate that a significant number of accidents are caused by “wheel-offs.” In fact, the American government does not specifically require proper wheel fastener torque nor does it constitute a direct violation under CSA. As long as the wheels are not cracked or broken and the bolt holes are not elongated, the vehicle is not in violation if none of the fasteners are missing or loose. And since CSA only assesses two points out of ten for wheel violations, they are not considered to be major safety issues.
But that doesn’t mean the goal has been reached. While wheel-related accidents are few and far between from a statistical standpoint, the potential for a fatality is always present. The torque wrench has never been a magic wand because clamping force is still what keeps the wheels on the vehicle. Everything from the condition of the fasteners and components to the seating of the brake drum can have a negative effect on clamping force and cause a properly torqued assembly to become loose down the road.
Problems like fatigued fasteners and improperly seated brake drums are difficult to spot in the field during installation. The best method for identifying most wheel end problems is to check the fastener torque after the first 50 to 100 miles to ensure none of the bolts have lost tension. But studies have shown that a few left- and right-hand turns combined with some railroad tracks or speed bumps can create enough flexing in the bolted joint to cause an out-of-service condition to become evident. Truck tire service providers commonly include a 50 to 100 mi. torque check on every invoice so the driver is warned after wheels have been installed. If the wheels end up becoming loose a few hundred or a thousand miles down the road, the installer will point to the warning and request to see documented proof that procedure was followed.
The bottom line? The owner and operator of the vehicle are responsible for the condition and maintenance of every mechanical component. Wheel issues do not appear to be on the CSA radar, and the growing popularity of properly torqued fasteners should keep it that way. The next frontier is to find a way to make torque checks part of every wheel maintenance program. It won’t be easy, but neither was introducing the torque wrench and look what that has done for the industry.