End of the Line

Identifying wheel end maintenance errors.

The days of one manually adjustable wheel end system have gone the way of the dinosaur and technicians are now faced with three options to indentify, install and maintain. TMC plans to address this issue in a new skill category at its 2006 technician skills competition, but in the end, techs are still the ones holding the torque wrench. Is the information getting through, and what happens if it doesn't?


Technicians involved in TMC's SuperTech 2006 can look forward to a well-rounded, full vehicle training event. Before the skill competition, technicians are required to take a 100 question written test. Kurt Hornicak, director of medium/heavy truck technical programs for ASE and the TMC SuperTech written test chairman, describes the benefits of this part of the competition.

"It reflects our previously existing truck certification areas, so there is a section on diesel engines, drive trains, braking systems, suspensions, steering, electrical, air conditioning and preventive maintenance," he says. "The nice thing about ASE certification is that it is as close as you can get to hands-on testing in a written test format because it is a job skills type certification test."

Adds Hornicak, "We're not asking people the theory of operation, but it's actual job application; their skills in a written form."

The TMC SuperTech competition is still in its infancy stages, having only begun last year, but is already drawing some serious involvement from techs and manufacturers. With the addition of a skill stations dealing specifically with wheel ends, technicians will have a chance to brush up on their skills in this oftentimes tricky maintenance area.


Roger Maye, national service manager for Consolidated Metco, will serve as co-chair of this year's wheel end station along with Bob Tanis, technical trainer for SKF.

"For many years, wheel hubs had bearings that were manually adjusted. That was the only option. Well, about ten years ago, the PreSet® and LMS™ wheel hubs and unitized wheel hubs came on the market. ," Maye says. "Properly identifying the type of hub is the first piece of the puzzle. From there, knowing the proper service requirements, and then knowing the maintenance requirements are two key things."

The manually adjusted is the most traditional, and often referred to as the "adjustable" type. "Pre-adjusted" (most commonly known by Meritor's brand name PreSet® and Dana's LMS™) and "unitized" wheel ends often require less maintenance. The pre-adjusted can be identified by the spacer between the bearings which controls bearing endplay. The unitized is different in the sense that it uses a bearing pack with Grade 2 grease and has a seal on both the inboard and outboard side. It is not field serviceable, and must be replaced fully in the event of a failure of one of its parts.

According to Maye, the first year of the wheel end skill station will stick to a fairly basic protocol. "The PreSet® and unitized remove bearing adjustment from the mechanic. We're going to focus on manually adjusting a wheel end, per one of the recommended practices from TMC, RP-618," he says. "We'll be varying this from year to year, but we want a mechanic to know how to manually adjust bearings and to be able to physically measure the endplay. We're going to be stressing the importance of properly identifying the wheel end that you're servicing, obtaining the proper work instructions, and then following through with the service based on those work instructions."


Maye goes on to cite what he sees as the major benefits of this event, and how he hopes to see TMC influence heavy truck technicians. "What I really hope to accomplish through the skills challenge is to make more mechanics aware of TMC and what's offered there," he says.

Maye adds, "I do a lot of mechanic training, and they are really not aware of TMC. Right now with the PreSet® and the unitized hubs—a lot of guys are getting to the point where they're servicing these for the first time; they're not really sure what to do. There's actually a TMC committee involved with identifying wheel ends."

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