Loads and selecting bearing size

There are two methods of determining the required bearing size:

  • selecting bearing size for static operating conditions
  • selecting bearing size for dynamic operating conditions
For variants VA201, VA208 and VA228, use the method of selecting bearing size for static operating conditions.

For variants VA237 and VA267, the appropriate method depends on the operating conditions. If the bearing operates under any of the following:

  • very low speeds (n < 10 r/min)
  • very slow oscillating movements
  • stationary under load for long periods of time

then use the method of selecting bearing size for static operating conditions.

Selecting bearing size for static operating conditions

The bearing size is selected based on the basic static load rating C0. Basic static load ratings for bearings are listed in the product tables.
For an equivalent static bearing load P0, the selected bearing must have a C0 value ≥ the value of requisite basic static load rating C0req specified in table 1.

NOTE

The values in table 1 are valid only when P0 = Fr. That is, when:

Fa < 0,8 Fr

and

Fa < 0,15 C0

where
P0=equivalent static bearing load [kN]
Fa=axial load [kN]
Fr=radial load [kN]
C0=basic static load rating [kN]

Selecting bearing size for dynamic operating conditions

The bearing size is selected1) based on the basic dynamic load rating C. Basic dynamic load ratings are listed in the product tables.
The type of operation must be identified as either:
  • intermittent (that is, standing still or used for short periods of time)
  • continuous (machinery utilized 8 hours, or more, per day)
For an equivalent dynamic bearing load P, the selected bearing must have a C value ≥ the value of the requisite basic dynamic load rating Creq specified in table 2 (for intermittent) or table 3 (for continuous operation).

NOTE

Table 2 and table 3 are valid only when P = Fr. That is:

Fa < 0,3 Fr

and

Fa < 0,15 C0

where
P=equivalent dynamic bearing load [kN]
Fr=radial load [kN]
Fa=axial load [kN]
C0=basic static load rating [kN]

  1. 1)Although the process described here for selecting bearing size for dynamic operating conditions is based on ISO 281:2007 basic dynamic load rating (C) for an equivalent-size standard bearing and calculated equivalent load (P), this selection process is not according to ISO 281 and is not a calculated rating life based on sub-surface fatigue as the failure criteria.
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