Slewing Ring

Friction Moment

(Rotation Torque)

The Friction Moment can be estimated for a slewing ring bearing using the formula noted below. The resulting values assume that the bearing is mounted according to the guidelines outlined in this catalog. This estimate only applies when load is applied to the bearing and does not reflect starting torque in an unloaded condition.

Also not considered are frictional torque generated by the lubricant, seals, and weight of the components. This does, however, provide a starting point, and with additional experience adjustments can be made in the assembly to accommodate additional torque.


friction moment formula

Mf = Bearing starting torque under load (ft-lbs)
μ = Coefficient of friction (0.006 typically)
M = Moment load (ft-Ibs)
Fa = Axial load (Ibs)
Fr = Radial load (Ibs)
Dpw = Bearing pitch diameter (ft)