4. Friction coefficient of bearings

The friction moment of rolling bearings can be obtained from their bearing bore diameter, using the following equation:

M=Pd/2

where: M: friction moment mN · m : friction coefficient (Table 4-1) P: load on the bearing N d: nominal bore diameter mm

Table 4-1  Friction coefficient

Type of bearing	Friction coefficient
Deep groove ball bearing	0.0010 to 0.0015
Angular contact ball bearing	0.0012 to 0.0020
Self-aligning ball bearing	0.0008 to 0.0012
Cylindrical roller bearing	0.0008 to 0.0012
Full complement type needle roller bearing	0.0025 to 0.0035
Needle roller and cage assembly	0.0020 to 0.0030
Tapered roller bearing	0.0017 to 0.0025
Spherical roller bearing	0.0020 to 0.0025
Thrust ball bearing	0.0010 to 0.0015
Spherical thrust roller bearing	0.0020 to 0.0025
<Ref> Plain bearing	0.01 to 0.02