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# Permissible speed

For polymer thrust ball bearings, the limiting speed (→ product table) is to be used as the determining factor to estimate the permissible speed.
The permissible speed depends on the applied load and the operating temperature. When both values are known, the adjustment factor for speed fn is to be calculated using

where
 fn = adjustment factor for speed P = applied bearing load [kN] fT = adjustment factor for temperature (diagram 1) C = basic dynamic load rating [kN] (→ product table)

Starting with the calculated adjustment factor for speed fn from the y-axis (diagram 1), the percentage of the limiting speed can be determined and the permissible speed can be calculated.

## Calculation example

• Input data
Bearing 6301/HR11TN, P = 0,245 kN, T = 90 °C (195 °F)
• Calculate the adjustment factor for speed fn

From the product table:
C = 0,31 kN
From diagram 1:
With T = 90 °C (195 °F) and rings made of POM → fT ≈ 0,87

• Calculate the permissible speed
From the product table:

nlim= 1 300 r/min
From diagram 1:
With fn= 0,91 and rings made of POM the percentage of nlim ≈ 40%

where
 nperm = permissible speed [r/min] nlim = limiting speed [r/min] (→ product table)