Timken Roller Bearing Life

Timken Roller Bearing Life T030

L10 life is the life that 90 percent of a group of apparently identical bearings will complete or exceed before the area of spalling reaches the defined 0.01 inch2 (6 mm2) size criterion. If handled, mounted, maintained, lubricated and used in the right way, the life of your tapered roller bearing will normally reach and even exceed the calculated L10 life.

When a sample of apparently identical bearings is run under specific laboratory conditions, 90 percent of these bearings can be expected to exhibit lives greater than the rated life. Then, only 10 percent of the bearings tested would have lives less than this rated life.

The bearing life equation is:
L10 = (C / P)10/3 Г— (B / n) Г— a
L10 in hours

  • C = radial rating of the bearing in lb f or N

  • P = radial load or dynamic equivalent radial load applied on the bearing in lbf or N. The calculation of P depends on the method (ISO or Timken) with combined axial and radial loading 

  • B = factor dependent on the method; B = 1.5 Г— 106 for the Timken method (3000 hours at 500 rev/min) and 106/60 for the ISO method
  • a = life adjustment factor ; a = 1, when environmental conditions are not considered ;

  • n = rotational speed in rev/min.

This can be illustrated as follows:

  • Doubling the load reduces life to one tenth.
  • Reducing load by one half increases life by ten,
  • Doubling speed reduces life by one half.
  • Reducing speed by one half doubles life.

In fact, the different life calculation methods applied (ISO 281, Timken method…) differ by the selection of the parameters used (i.e. the Timken formula is based on 90 million revolutions, whereas the others are based on 1 million revolutions).


  • On February 17, 2018