End of the Line

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."


Fortunately for the technicians not involved in this year's competition, TMC wasn't the only group to discover a need for more clarification and training when it comes to wheel ends: manufacturers have become more consistent in offering solutions to deal with confusion amidst wheel end maintenance issues.

SKF Vehicle Service Market offers its Trouble Free Operations Program (TFO) in order to help fleets maintain consistent and successful service of their wheel ends. Initially, TFO advises a fleet on the proper seal relative to their particular application.

Depending on the duty, they may need one with a longer life seal to keep out contamination.

Leslie Kern, senior product manager, heavy duty market, SKF, describes the additional benefits of TFO: "Included with Trouble Free Operation is our training, and we find that to be very important for the technician," Kern says. "Our instruction includes the TMC Recommended Practices 618 bearing adjustment procedure and endplay reading. Achieving the proper bearing adjustment will go a long way in getting the longest service interval possible for a wheel end."


After TFO covers wheel end choice and maintenance, the program rounds out with a follow-up procedure, should a problem occur. "The TFO is a full circle program, and whenever there is a seal or bearing failure, we take that seal or bearing—with the customer—and diagnose what caused it to fail," Kern says.

"Very often it leaves evidence or ‘witness marks,' so you can see, maybe the wheel was installed cocked, or the bearing was subjected to heat which could be an over-tightened bearing adjustment. These are things to help reinforce to the installers the training that they've received up front. If they can see for themselves the effects of an improper installation, that helps reinforce the value of following the procedures that we recommend," she says. "It's important that the technician follow the proper installation and maintenance procedure, and the drivers do the required walk around the vehicle every time they get out."


Dana has taken the approach of designing a hub system that tries to bypass maintenance as much as possible. The Spicer® LMS™ (low maintenance system) is a pre-adjusted system which attempts to address several of the difficult elements behind wheel end consistency and longevity.

"Our LMS™ hub system included precision machine hub and spacer and premium bearings so that we could set the endplay properly every time in a wheel end," says Steve Slesinski, director of product planning for Dana's commercial vehicle systems. "By controlling that endplay, or pre-load, properly, it takes the adjustment out of setting wheel endplay. By controlling that endplay, it significantly improved the life of a good wheel seal."

Slesinski adds, "The next phase of improving the evolution of the wheel end was the venting system, where vents were developed to eliminate water from getting into the wheel end from either rain, flooding or high pressure spray." This led to an industry-wide adaptation of wheel ends to include venting systems to keep out water and, in the process, extend the life of the wheel end lubricant.

"We took that a step further with the LMS™ hub and hub cap by also putting an identification of the wheel end on the outside." The powder blue exterior is visible from across the garage, or even across the highway. "They're doing 70 miles an hour and the truck is coming at you, you can see it across the highway," Slesinski says. "If you're a maintenance manager and you have trucks parked in the yard and you want to know which you need to adjust, you could quickly see which ones."

Dana also offers a training program in the form of the Roadranger Field Service and Sales Organization.


Considering how tiny some of these parts are, the consequences of improper maintenance to a wheel end can be surprisingly disastrous and expensive. Leo Wenstrup, senior product manager for Dana's drive axles stresses the importance of using high quality, compatible lubricant for the system.

"The lubricant is important from a couple of aspects," Wenstrup says. "One is the additive package. If it's a very aggressive additive package, it can attack the wheel seal itself and cause the seal to age prematurely and take away from the life of the seal."

Adds SKF's Kern, "Lubrication awareness is another important part of our TFO program. It's important that the lubrication is an OEM recommendation and that it meets the requirements of the application; also to inspect the lubrication for contamination—water, dirt or even metal particles from a worn component," she says.

Other maintenance errors, such as improper tightening, lead to their own dangerous outcomes: "If you have an extremely over-tight wheel end which could escalate temperature quickly, the driver may not have the opportunity to check for wetness—there could be a wheel fire if it goes undetected and, ultimately, lead to a catastrophic failure of that wheel end," Kern says.


Because it is such a critical item in overall vehicle operations, correct maintenance is key and can be as simple as just knowing your wheel ends.

"We think that steering, brakes and wheel ends are among the most critical elements on the vehicle because they are directly related to vehicle control, and if you lose one of those, it's certainly critical," Maye says.

"The first thing we emphasise is identifying which wheel end they're working on. Once they do that, following the manufacturer's recommendations for inspection and service goes a long way to preventing pre-mature failures," he says. "It's different—technicians see some things for the first time that they haven't seen previously, and sometimes they are aware of what they are looking at, and somtimes they're not."

TMC's 2006 SuperTech competition will be held Sept. 18-21 in Austin TX. For more information, visit http://tmc.truckline.com