By Daniel Russell, Maine State Police Commercial Enforcement Unit – Motor Carrier Inspector
As you all know, Troopers and Motor Carrier Inspectors from the Maine State Police work day in and day out throughout the State of Maine, providing many services and many functions to a variety of stakeholders in our state. Our job is sometimes a very technically complicated one, providing roadside inspections, speaking engagements, company audits, and even judging the State Truck Driving Championships. We have a responsibility to the people of the State of Maine to ensure the safety of the motoring public by taking actions to reduce crashes, injuries, and fatalities involving commercial vehicles that use our public ways. Most people equate this function to our roadside stops and inspections of commercial vehicles, but most days there are many other activities going on, such as distracted driving details focusing on passenger cars operating in the vicinity of large trucks, educating industry and the public on regulations and best practices, or just taking the extra time to show a driver how to locate a particular issue during a pre-trip.
This past spring, myself and my co-workers answered a call that we all had prayed would never come, to investigate a fatal crash involving a commercial vehicle and a Maine State Police Detective. Some lessons were learned during this investigation that I want to share with you, because it could very well save a life.
As a Class A CDL holder, a licensed State Inspection Technician, a CVSA Certified CMV Inspector, and a qualified Heavy Vehicle Autopsist for the Maine State Police Crash Reconstruction Unit; when I get behind the wheel of a large truck, one of my greatest fears is some part of that vehicle, be it a trailer, wheel, or spare tire coming separated from the vehicle. I think many professional drivers would agree, trucks generally don’t have very small parts, and when they come off the truck at 60, 65, or 70 miles per hour, the potential effects are devastating. I am going to focus on tire/wheel components for the purposes of this article, but nothing falling off the truck is a good day.
We are all probably somewhat familiar with stud piloted, hub piloted, and spoke wheels. One of the foremost things that needs to be done is to make sure components for those wheel systems are never mixed! It sounds simple, but can your drivers distinguish between a flange nut for a hub piloted wheel, or an outer cap nut for a stud piloted wheel during their pre-trip inspection? We recently found a motorcoach operating with a hub piloted wheel on a tag axle that had a stud pilot hub set up, with stud piloted hardware. When the wheel was removed, three studs were broken off in a way they couldn’t be seen with the wheel on.
Another important piece of the puzzle is obviously torque. Too much Torque will stretch studs. Stretched studs will fracture and fall off. To little torque and the nuts can back off. Forget to retorque? The wheels and drum can settle, and the nuts can back off.
After spending hours this year talking to and meeting design engineers from axle and suspension companies, hub companies, and some of the very best and brightest fleet maintenance personnel I know, I discovered something I didn’t know: If you are not familiar with the term “Clamp Load” or “Clamp Force” and you are installing wheels, it is time to get some better training under your belt. I had previously heard the term many times, but had never given it the level of thought I did this year. Think of clamp force as the magical force that supports all of the weight of the truck, and keeps the wheels on. If you do not have correct clamp force, which you may not for many different reasons, your wheels are eventually coming off.
I have also learned that it cannot be overlooked when installing hub piloted wheels, that the wheel is properly centered in reference to the hub and the studs. I think many people believe, as did I, that this isn’t an issue with hub piloted wheels because the purpose of the pilots is to center everything. I will simply say, if you believe this, you are wrong, as was I.
The Occupational Safety and Health Administration requires anyone who works on medium and heavy duty truck and bus wheels to have documented minimum training before doing those tasks. Ask yourself: Are the people who put the wheels on my trucks compliant with OSHA training standards? These standards are just a bare legal minimum to be allowed to complete the task, not even talking about ATA TMC recommendations or best practices.
During CVSA roadside inspections, personnel throughout North America look for damaged wheels, such as cracking around the hand holes, in the area of the stud holes, around the mounting surface, and along the OEM welds. Repair welding of any steel or aluminum wheels is not permitted except to OEM welds on steel wheels where the disc and rim attach. Any damage or elongation in the stud holes that is visible will render a vehicle immediately out of service. Failing to have any visible amount of oil in oil bath hub bearings, or an active leak from the wheel bearings, or a missing oil filler plug from your hubcap will also render a vehicle immediately out of service. Are your drivers properly trained to inspect and recognize these issues before the head out? Do your wheel refinishing practices make it easy or hard for your drivers and maintenance personnel to find defects in the wheel surface (rusty steel wheels are harder to find cracks in)?
Many of these issues I have discussed cannot been seen during a roadside CVSA inspection. I can’t determine if your wheel studs are stretched. I can’t determine if the correct torque sequence that is necessary to properly center those wheels was used. I can’t tell if you inflated your tires in a safety cage during a roadside CVSA inspection. Unfortunately, we can’t tell many of these things until something bad has already happened and we are taking things apart to try to figure out where it all went so wrong. What I can see is if your employees have received the correct training and have the correct equipment to complete this work. We are watching wheel ends now as close as we ever have and we are finding violations that we have never previously noticed before. I attended the CVSA Annual Conference in September discussing proposals to add some items in the wheel and fastener section to the Standard Out of Service Criteria used throughout North America.
Right now is the correct time to get ahead of wheel offs and increased scrutiny of wheel ends on your vehicles by enforcement. Make sure your employees have the best training that you can reasonably get them to install and service your tires and wheels. Make sure that they have and are using the torque wrench every time! Make sure you are not reinstalling cracked wheels, worn out hubs, bad fasteners, or stretched studs. Make sure you are complying with OSHA and FMCSA standards in your fleet maintenance shop. If you have wheels coming off your vehicles, and you are simply happy that they haven’t hit anything or anyone, how many more times are you willing to roll the dice?