There are many factors that affect the friction resistance of the slewing ring, so it is difficult to calculate it accurately. The following formula is usually used to calculate the rotational friction resistance of slewing bearing approximately:
Mf= D/2.NGM.μd1 +DH/2 .NH.μd2
Where D is the diameter of the rolling body that receives the axial force Gp and the tilting moment M;
NGM – the sum of the positive pressures on the rolling elements produced by the axial force Gp and the tilting moment M;
μd1——the equivalent friction coefficient of the rolling element and the raceway subject to the axial force, which can be approximated as μd1=0.01;
DH – the diameter of the rolling element which bears the radial force Hp;
NH – the sum of the positive pressures on the rolling elements produced by the radial force Hp;
μd2——the equivalent friction coefficient of rolling element and raceway subject to radial force, which can be approximated as μd2=0.01
In order to obtain the friction resistance torque Mf, it is first necessary to determine the sum of the positive pressures on the rolling elements NGM and NH.