Wheel Off Again.
G. Ray Gompf, CD
Full disclosure. I wasn’t there, I didn’t see the wreck first hand. I did however see the investigators photographs and I’m not a novice at being analytical. I’ve seen, even commented, on the Facebook and Twitter comments blaming the trucker, the trucking company, the lack of maintenance, and all the other excuses for this particular wheel off.
Oh, you didn’t hear about it? This week a large tractor trailer lost a set of wheels that smashed into an SUV on the 400 Highway north of Toronto, killing the driver of the SUV.
Clearly, from the evidence photographs posted by the investigators, the studs failed and sheared off as they exit the brake drum and go through the rims. This type of incident could not be predicted by a walk around; a daily inspection. The lug nuts were tight and that’s all a daily inspection would show.
The shear points were clean and showed no evidence of rust, simply a fresh shearing. Clearly, not the driver’s fault. Did the tire installer over torque the nuts? Possibly! But there’s another issue that few talk about. Were the studs and lug nuts not up to manufacturers specifications? Were the studs and lug nuts mismarked with the wrong identifiers? Where was the studs and lug nuts made offshore? If so, can we trust these offshore manufacturers to produce the quality product required for these high stress situations? How old where the studs and lug nuts? It’s obvious that metal fatigue was a problem but why? Who should have made note and corrections? Is this simply systemic failure to do proper maintenance every time?
New studs and lug nuts have a usable life. Those lug nuts that get removed due to a flat tire may get reused — maybe, but essentially lug nuts should only be used once. The lug nut and the stud to which it’s attached purposely stretch each other. They are under constant pressure and time can and will cause failure. Therefore, exacting standards must be maintained in the manufacturing process to prevent premature failure.
Every time brakes shoes are changed, the studs must be changed on the drums. Every time the lug nuts are taken off, except during on road emergencies, they must be replaced. There shouldn’t even be a maintenance question in this case. The studs and nuts are virtually no cost items. Replace them, even if the “look” good. If they’ve got a winter on them, change them.