The proper tightening of wheel fasteners is a topic that has certainly had its fair share of coverage in the last few decades, and for good reason. Although individual wheel separations are not tracked by the NTSB, it is estimated that approximately 1,000 wheel separations occur annually in the United States, often with devastating effects. See the National Transportation Safety Board’s Safety Recommendation regarding this issue.
I would also encourage you to visit Wheel-Check®’s “In the Press” page to see real stories about wheel detachment, and get a personal feel for how important this issue is.
The majority of wheel separations in the U.S. are primarily attributed to two maintenance-related issues, bearing failure due to lack of lubrication, and improper tightening of wheel fasteners. All truck and wheel OEMs, along with other commercial vehicle safety authorities, provide recommended tightening procedures and specifications, so there is no feasible argument for a lack of information being the issue. The presence or absence of systematic and detailed attention is where the rubber meets the road.
Correctly tightening wheel fasteners is not a “one and done” process. Even if a power unit or trailer rolls out of the shop with the proper amount of clamping force applied to each wheel, it can easily be out of spec within the first 5-100 miles down the road. Wheel fasteners often need to be checked and re-torqued as normal vehicle operation can cause loosening. This practice should not be ignored, and should be a vital part of any regular maintenance process. Whether it is or not, is up to the individual operator.
It is important to understand that over tightening fasteners can be just as devastating and dangerous as under tightening them. Over tightening wheel fasteners often causes fatigue and damage to system components. When lugs are stretched beyond their rated yield, they are no longer safe and must be replaced. This type of damage is commonly associated with the improper use of high powered pneumatic impact wrenches and cheater bars.
Essentially, the proper tightening of wheel fasteners is no different than any other piece of a comprehensive maintenance and inspection routine. Like everything else on the check sheet, it’s there to keep everyone safe and on the road.
If you are unsure about the proper process of tightening wheel fasteners on your equipment, reference the equipment’s manual or contact the OEM directly.
Truckinginfo Equipment Editor, Jim Park, offers some outstanding resources and covers this issue quite thoroughly in the following articles:
If you are interested in on-site PM service that includes properly tightening wheel fasteners, contact us.