While attention has been paid to today’s engine and emissions technology, upgraded braking and steering systems and even state-of-the-art comfort and convenience products, the wheel bearing has been left to languish in relative obscurity, say some experts.
This is not to suggest that they are outdated componentry. They may look the same as they did in the past, but wheel bearing technology has quietly changed and today’s fleet managers may not even realize what they don’t know. However, this confusion can be costly in many ways.
“There’s a real training opportunity out there right now,” explains Mark Stangl, east regional manager, heavy duty aftermarket, The Timken Co., “but it’s not perceived as necessary because the changes in wheel bearings have been more subtle than, say, engines or brakes.”
Stangl says part of the issue is the fact that, for all the substantial improvements in today’s wheel bearing technology, cosmetically they look very similar to those found on older vehicles. Until about 1995, explains Stangl and Timken’s west regional manager Dan Humphrey, manually adjustable wheel bearings were the norm. Preset wheel bearings were introduced as a spec-only item that gradually become more accepted, primarily through selection by larger fleets.
“In 2007, the preset bearing style became the OE choice for drive and steer axles,” says Humphrey. “They’re growing in popularity on trailers but they’re not yet standard.”
A manually adjusted bearing allows technicians to make whatever adjustments they deem necessary which, say the Timken spokesmen, is one of its drawbacks. “The preadjusted wheel end is basically a system,” says Stangl. “It’s created by adding a spacer making the bearings and hub more precise. Why would you want to go through all that? For the technician it makes the job more repeatable.”
Stangl says it’s this repeatability that earns the preset bearing its stripes. “Every technician can do the job more consistently and more quickly. We’re taking a lot of the variables that can come with misadjusted wheel ends and tweak the design using a spacer. This gives more consistency with the final wheel end setting. And it’s where training could be helpful.”
Typically, explains Leslie Kern, SKF heavy duty product development Manager, failures fall under one of two headings: installation-related or environmental.
By its nature, she says, installation-related failures could be avoided with the proper technique, proper use of tools and using quality product. Achieving the proper bearing adjustment is very important not only to maximizing life but also preventing initial and even catastrophic failure.
“Today’s wheel end designs require different adjustment procedures and it is important that the technician know and follow the procedure for each wheel end type,” she agrees. “Care needs to be taken when handling the bearings prior to installation.”
Also, says Kern, keep the bearings clean before installation. “Prevent exposure to dirt. It doesn’t take much of a particle of debris to start the escalation of bearing failure. Never use a bearing that has been dropped. Even if damage isn’t obvious, don’t risk an expensive, unplanned, service to save a few dollars. The cost will be much higher down the road.”
Installed properly, bearings can have an almost indefinite life, Kern says. However, attention to its environment doesn’t end following installation.
“Bearings must be continuously lubricated to function properly. Lack of lubrication will create friction and temperature rise which will impact the seal’s ability to seal, further aggravating the condition.”
Justen Wahl at NTN Bower concurs: “Many bearings fail because of lubrication and contamination issues, both of which can initiate at the time of installation or from factors seen in the environment the bearing operates in. These issues can also result from improper setting of the bearing. Setting is what establishes the end-play in the bearing. Too much end play can lead to premature seal failure, and too little or negative end-play can cause overheating which can lead to lubrication breakdown. These issues can be avoided by following recommended installation and maintenance procedures that incorporate proper torque setting and endplay measuring techniques,” says NTN Bower’s Sales Manager for U.S. Heavy Duty Automotive and HD Aftermarket.
Because of the variations in installation and service procedures, it’s imperative that fleets understand what they have in operation. “Is it manually adjusted? Pre-adjusted? Unitized? They need proper training to know what is out there and how to service it,” says Humphrey.
Luckily, all of the experts interviewed for this article say their company is eager to provide training, in person at your location, online or through any number of printed technical brochures designed to improve the lifespan of the wheel bearings.
“There are a lot of bearings not living up to their full potential because the guys who are opening the box and turning the wrench may not be up to date on all the details of the design,” says Stangl.
“To be sure your bearing purchase will have the most extended life only buy from industry-leading bearing manufacturers who have engineering and manufacturing expertise to make a quality product and can provide technical assistance,” cautions Kern. “Reverse engineered products have the potential for falling quite short on performance.”
In many segments of the transportation aftermarket, counterfeit parts are a very real concern. NTN Bower’s Wahl says wheel bearings are no exception. ”Counterfeit bearings are a growing concern in many bearing markets. Fleets can avoid this issue by utilizing trusted sources for their bearing requirements, and actively monitoring the product (brand, country of origin, etc.) those sources provide. More information on counterfeit bearings can be found at www.stopfakebearings.com.”
Even if parts aren’t counterfeit (blatant copies of brand-name parts) it doesn’t mean they’re right for your application. It’s more a case of meeting performance expectations. The part may have the dimensional ability to fit your vehicle – but are you confident in its quality?
“There are about 50 tapered roller bearings on a truck-trailer rig,” says Timken’s Stangl. “But we often see a greater emphasis on the OTHER bearings in use. We certainly don’t want to blow an engine because of a cheap bearing or lose an axle because the pinion bearing wasn’t as good. But the real consequences of a wheel coming off a truck because of a wheel bearing failure is more extreme. Be sure to double-check interchange numbers when ordering new bearings.”
This attention to detail is critical, explains Wahl. “Ask suppliers questions about ‘special’ bearings with part numbers that are different from the industry standards that have been historically bought. This can help fleets understand how the special bearings are different from the standard designs, and then determine if they are comfortable with the investment.”
Whether it’s putting an economy-idled vehicle back into service, understanding the impact Super Single tires have on wheel bearing life or knowing proper installation and maintenance techniques, suppliers are eager to train your staff. The consequences of ignorance can be severe.
