Thirteen years ago, two back-to-back fatal wheel-off incidents on Toronto highways brought the problem to center stage in Ontario.
Committees were struck, analysis was performed and theories advanced, recommendations came out of woodwork, and controversial, overreaching laws were passed. But wheels continue to part company with vehicles fairly regularly. Apparently, they always have.
In the fall of 1991, four years prior to the incidents that brought the issue home in Ontario, five separate wheel-off incidents killed seven people on U.S. highways. Just last year, in May, 2007, five more wheel-off incidents in the space of a few weeks killed one motorist and damaged several cars — all in the Seattle area.
Though the incidence of heavy truck-wheel separation accidents is small — 750 to 1,050 per year, compared to the total number of truck accidents annually — they seldom fail to make the front section of the newspapers.
The Seattle incidents were traced back to five different mechanical causes. Both of the now-famous Ontario incidents had different root causes. The five incidents in 1991 promoted the National Transportation Safety Board (NTSB) to investigate. They found several causes. Among other things, the NTSB found:
— The leading causes of wheel separations from medium/heavy trucks are improper tightening of wheel fasteners and bearing failure; both are the result of inadequate maintenance.
— Under-tightening of wheel fasteners usually results from the failure to follow recommended wheel maintenance practices, such as always using a torque wrench, following proper tightening procedures, using only compatible components, and avoiding paint build-up, debris, oil, or rust between wheel fasteners, threads, and mating surfaces.
— Over-tightening can more easily result from using an air impact wrench instead of a torque wrench.
— The trucking industry lacks uniform model guidelines for maintenance and inspection of all types of medium/heavy truck wheels.
— Wheel bearing failure can result from inadequate lubrication, bearing misalignment, improper bearing nut adjustment, or overload.
Where have we heard that before? The causal factors from 1991 sound suspiciously like the recommendations issued after the Ontario incidents, and probably, they’d be the same issued following investigations of the Seattle incidents last year.
In September, 1995, the Professional Engineers of Ontario, the licensing and regulating body for engineering in the province, issued a 20-page report outlining possible causes for the wheel-offs, and offered 11 recommendations to prevent further incidents. They included specific training for wheel-end mechanics and technicians, quality-control initiatives at the manufacturing stage, establishing maintenance procedures and record-keeping requirements, and others.
Training programs have been created, policies have been put in place, and records are being kept, but the wheels keep coming off.
The problem, says Kelly Crozier, is process and accountability — or lack of it.
Process and Procedure:
"When I talk candidly to fleet managers, I find that very few have a wheel-retention program in place, and I cannot find any who actually enforce the practice of wheel retorques," says Crozier, an independent maintenance consultant working in British Columbia.
One of the carriers he works with suffered two wheel-off incidents in 2007. Damage to equipment was minimal and no personal injuries resulted. They got lucky in that regard, but the incidents brought the need for better wheel service to management’s attention.
Crozier’s firm, Border Fleet Services, has developed a wheel retention program for fleets that includes software for tracking wheel maintenance events (scheduled and non-scheduled) that includes a lock-out feature preventing a truck from being dispatched or kept in service until follow up procedures have been completed, verified, and logged.
"Any equipment with a pending retorque repair order older than 48 hours cannot be dispatched in the dispatch software," Crozier says.
The leading causes of wheel separations from heavy trucks are improper tightening of wheel fasteners and bearing failure.
Retorque orders are actually the final stage in a multi-tiered approach that begins with spec’ing the proper equipment and tools. There’s mandatory training for shop personnel in proper wheel-end service procedures, and training for management and administrative personnel on the various checks within the system to ensure procedures have been followed.
In a addition to a predictive maintenance program that requires older in-service equipment be retorqued regularly and inspected at appropriate intervals, there is a materials-testing program to sample older in-service parts to predict the likelihood of an age- or mileage-based failure.
It’s all predicated on management buy in, of course.
As Crozier points out, preventing wheel-offs isn’t necessarily difficult in and of itself, but it requires fleet management take a proactive and pre-emptive approach to the problem.
Every time a wheel is removed for any reason, it’s logged and a retorque is mandated, he explains. Once the requirement is in the system, it can’t be bypassed except by some deliberate effort, and there’s accountability built into the system, from drivers to dispatch to the admin staff.
"Enforcement of the program requires participation at the highest level. In this case, the president of the carrier agreed to allow the maintenance staff to lock out electronic dispatch of equipment by operations 48 hours after an outstanding retorque was triggered," Crozier explains. "The equipment could be dispatched once manually [allowing a truck to travel up to 100 km] before completing the retorque requirement, but dispatchers are subject to dismissal if they perform two manual dispatches without justification."
The repair shop doing the work must send an invoice to the maintenance shop before the dispatch is unlocked. The maintenance shop has a list of approved vendors continent wide, and all repairs must be approved by the maintenance shop since the shop approves payment.
"Granted, a poorly run franchise of a quality organization may perform substandard work," Crozier acknowledges, "but you can only go so far to provide due diligence …"
The Driver’s Role
Getting driver buy in is the toughest part, Crozier says, although the primary factor for success in wheel retorques is the driver.
"Most drivers I have met will not voluntarily participate in these programs. The success of the program where I am currently contracted was only possible when a method was devised to force the driver population to comply," he says.
Drivers are alerted to the need for a retorque by placing a two-part warning tag either on the steering wheel of a power unit, or on the gladhand connectors on a trailer. The person attaching the wheels to the equipment fills out the ticket, which is then attached to the repair order and entered into the maintenance and dispatch systems.
Wheel torque indictors are placed on one lug nut of each wheel that has been serviced.
This of course addresses one of the key causes of wheel-off incidents: improper tightening of wheel fasteners. The shop has to do the job properly in the first place, and drivers must ensure the wheels are properly retorqued following a wheel service. This system establishes the process, and adds accountability to ensure the work is done.