Get up to 30% more mileage out of your tires.
Discover Doctor Preload® Bearing Adjustment Tools and Temper-Loc® Spindle Nuts
Doctor Preload bearing adjustment tools allow your technicians to quickly and accurately adjust wheel end bearings to SAE standard light preload settings while measuring preload forces all the way through the adjustment process and at the final preload setting.
SAE International, the technical and engineering leaders of the vehicle industry, published the specifications for light preload in heavy duty truck and bus wheel end bearings for optimal performance in March 2001. At that time there was no practical and safe way to adjust bearings to SAE specified preloads – until Temper Axle introduced Doctor Preload to the industry in 2009. Now there are no more excuses:
Fleets report achieving up to 30% increases in tire life due to more even tread wear. Wheel seal and bearing life and brake operation are also optimized with preload settings.
Ready to give it a try? Here’s how it works.
One Minute. Four Easy Steps.
Thorough inspection by the trained technician ensures a properly adjusted and secured wheel end bearing.
Over the past 10 years, fleets of all sizes have realized compelling benefits from this breakthrough technology, resulting in revolutionary wheel end performance levels.
Simple. Proven. Stable.
Doctor Preload also saves a lot of technician time.
Good Technicians are hard to recruit. Help them be more efficient.
Using Doctor Preload to adjust a wheel end bearing takes about one minute from start to finish. Together with Temper-Loc Spindle Nut, specially designed to work with Doctor Preload, the tool saves technicians hours of time by simplifying the steps involved in bearing adjustment and taking the guesswork out of consistently achieving preload settings. Fleets realize huge time and cost savings over other methods, which add up quickly.
Temper-Loc Spindle Nuts enable precise adjustment and come with a fingertip-control retainer ring technicians appreciate for its ease of use and safe operation. EasyView® tabs help technicians confirm spindle nuts are securely installed.
Retainer tab entering nut groove
Retainer tab securely engaged in nut groove
Wheel end tapered roller bearings are designed to be set to preload. They are not designed to be “loose” or have endplay. In preload condition, all clearances (endplay) between components in the wheel end assembly are completely eliminated and the bearings are slightly compressed.
Keeping a light preload force on the bearings maintains roller alignment so they roll the way they should. The rest of the wheel end components including tires, seals, and brakes are all designed to work best under preloaded bearing settings.
Preload is not Pre-adjusted: “Pre-adjusted” is a term that refers to wheel ends with a cone spacer and higher cost “close tolerance bearings” that will set to endplay and reduce tire life. They cannot be adjusted to a better setting, without removal of the cone spacer.
Preload is not torque: Torque should never be used to adjust bearings to a presumed preload condition because the final preload setting cannot be measured, thus creating unsafe inconsistency in bearing settings.
Safety demands that preload always is set using direct measurement of the preload forces.
Yes: The more endplay, the more money you’ll spend on vehicle operation and maintenance. Bearings set to any amount of endplay, as small as a few thousandths of an inch, cause rapid and irregular tire wear, resulting in shorter tire and tread life. Developed by tire and chassis engineers, the Radial Tire Conditions Analysis Guide, Technology & Maintenance Council (TMC), Fourth Edition, identifies 14 different common irregular tire wear patterns that are caused by improper bearing adjustment. Setting to preload helps solve these problems. By removing endplay and setting bearings to preload, irregular wear is reduced or eliminated, enabling optimum tire performance and leaving less money on the road.
When truck and trailer wheel ends are adjusted in a controlled manner, slight preload can be beneficial to the success of long wheel end life. Slight preload can improve bearing, seal, and tire life, but only if the entire process is in control. ‘In control’ means that you actually know the bearing setting process will result in a consistent bearing setting range.
Bearing and seal life can be maximized when the bearings are adjusted to a light, controlled preload setting.
Wheel ends that operate in slight preload or with endplay tolerances tighter than .001 to .005” may offer superior bearing and wheel end performance and longevity.
Our tools are proven to deliver significant advantages to fleets of all sizes – from a single owner operator to large national fleets. Doctor Preload and Temper-Loc spindle nuts used together offer significant benefits.
Watch our videos and download our instructions and catalog sheets to see how easy it is to use our system to deliver pinpoint accuracy.
Since converting our fleet to preload settings with Doctor Preload tools, wheel ends are no longer an issue. Our tire wear problems, which were often severe, are totally gone.
I’m a firm believer in the Doctor Preload and Temper-Loc nut system. It’s helped us cut recap use by one-third over two years, and reduce inside tire edge wear-out by 90%. Our wheel ends run truer and run longer.
Setting the proper preload can’t be anything but good. That’s why we’ve invested in Doctor Preload and Temper-Loc spindle nuts. I’m glad I spent money on this system and it’s working well on my trailers.
We believe in the product and it’s doing exactly what it promised to do – keeping consistent preload on the wheel bearings and contributing to good to better tire wear. I use the system on roughly 100 trailers and it’s keeping preload on the wheel bearings. It has been a good addition to my fleet.
The system has been a valuable addition to our maintenance operation. On our two most recent orders of new trailers, we insisted that the OEMs install Temper-Loc nuts, which puts us on the right track with properly managed bearing settings.
Call us today, (518) 853-3467, or feel free to fill out the form below and a member of our team will reach out to schedule a call with you.
Doctor Preload and/or its use may be covered by the following patents.
Temper-Loc and/or its use may be covered by the following patents.
SafetyCert and/or its use may be covered by the following patents.