1994-11-01

The Means to Accurately Install Tapered Roller Bearings to Specified Values of Acceptable Preload on Axles of Highway Vehicles 942295

Developments in axle nut configurations now make it possible to position wheel assemblies on the axle spindles of heavy duty combination tractor/trailer vehicles using new installation procedures to assure ideal adjustment of the tapered roller bearings. The ability of all mechanics to accurately control the assembly of wheel end components will be enhanced with axle nut designs conceived in the last two years.
Of great significance in this area of interest are pronouncements by tapered roller bearing engineers who now advocate that longer life will be realized for all wheel end components if a limited amount of tapered roller bearing “preload” is introduced and maintained with a mean of finite axle nut adjustment. Until recently, there appeared to be reluctance on the part of the tapered roller bearing manufacturers to advocate improvement of tapered roller bearing service life with application of preload pressure. This was because of the common belief that it was impossible for the average mechanic to mount and adjust the wheel on the axle within a controlled range of bearing pressure. For that reason, all bearing manufacturers specified assembly procedures calling for a degree of freedom between .001″ and .010″ of clearance as measured with a dial indicator. Although this recommended range of end-play was recently revised to .001″ and .005″, even better conditions are now possible. With some newly designed axle nuts, an improved performance potential of wheel and axle assemblies can be assured. Of major importance is the fact that it will no longer be necessary for the mechanic to use a dial indicator to achieve ideal bearing adjustment.
This technical paper will explain the first double axle nut system having the means to apply a specific amount of tapered roller bearing “preload” and to retain that value of pressure while being secured in its final jammed condition. Also noteworthy is the fact that the concept will universally satisfy the installation requirements at all three wheel positions on the tractor/trailer combination vehicle; the steer axle, the tractor drive axles, and the trailer axles.

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