Load calculations

The forces and torques acting on the bearing position are decisive for selecting the optimum bearing size and guaranteeing the required service life.

Direction and distribution of forces

Pure radial load F_r

Loads that must be taken into account:
1. Weight of the moving part
2. Centrifugal force (imbalance)
3. Dynamic load (acceleration, deceleration)
4. Force due to energy transmission (pulley, gears, etc.)
5. Preload for duplex bearings¹

Pure axial load F_a

Note: To ensure that an axial load can be supported by several ball bearings, they must be arranged in pairs¹ , either ring to ring or with very precisely manufactured intermediate rings.

Combined loads

(radial and axial)

1) see duplex installation

Q_r = cos ß – Q
Q_a = sin ß – Q

Normal installation

F_a = Q_a (the axial load is absorbed by only one ball bearing)

Duplex installation in tandem design
(intermediate ring)
F_r = Q_r
F_a = Q_a

Preload F_ap

Ball bearings in duplex form¹

(O arrangement or X arrangement) have a preload (F_ap) that is above or below the axial load F_a.

This preload Fap must be adjusted to the operating conditions and the desired life expectancy.