BEARING SETTING

●Setting 

   Setting is defined as the axial clearance between roller and raceway. Establishing the setting at the time of assembly is an 

   inherent advantage of tapered roller bearings. They can be setto provide optimum performance in almost any application. Fig. 1

   gives an example of the relationship between fatigue life and bearing setting. Unlike some types of anti-friction bearings,tapered

   roller bearings do not rely strictly on housing or shaft fits to obtain a certain bearing setting. One ring can be moved axially 

   relative to the other to obtain the desired bearing setting.

Fig. 1.Typical life vs. setting curve.

   At assembly, the conditions of bearing setting are defined as:

● Endplay (EP)

   An axial clearance between rollers and raceways producing a measurable axial shaft movement when a small axial force is 

   applied-first in one direction then in the other, while oscillating or rotating the shaft. See fig. 2.

Fig. 2.Internal clearance – endplay

● Preload (PL)

   An axial interference between rollers and raceways suchthat there is no measurable axial shaft movement when a small axial

   force is applied-in both directions-while oscillating or rotating the shaft.

● Line-to-line

   Azero setting condition: the transitional point between endplay and preload.

   Bearing setting obtained during initial assembly and adjustment is the cold or ambient bearing setting, and is established before 

   the equipment is subjected to service.

   Bearing setting during operation is known as the operating bearing setting, and is a result of changes in the ambient bearing 

   setting due to thermal expansion and deflections encountered during service.

   The ambient bearing setting necessary to produce the optimum operating bearing setting varies with the application. 

   Application experience or testing generally determines optimum settings.Frequently, however, the exact relationship of ambient 

   to operating bearing setting is unknown and an educated estimate has to be made. To determine a suggested ambientbearing 

   setting for a specific application, contact your engineer.

   Generally, the ideal operating bearing setting is near zero to maximize bearing life (fig. 1). Most bearings are set with endplay at 

   assembly to reach the desired near-zero setting at operating temperature.

   There is an ideal bearing setting value for every application. Toachieve this condition, the bearing setting musttake into account 

   deflection under load (radial + axial) as well as thermal expansions and material used.

● Standard mounting 

   Operating setting = mounted setting temperature effect +deflection

● Pre-set assemblies

   Mounted EP or PL = bench EP or bench PL- effect of fits

   Operating setting = mounted EP or PL (MEP or MPL) +deflection temperature effect

   The temperature and fit effects will depend upon the type of mounting, bearing geometry and size, shaft and housing sizes, and 

   material as defined in the following sections.