Why must bearing mounting force avoid passing through the rolling elements?

The short answer

Because transmitting mounting force through rolling contacts can create damaging indentation before operation begins. The intended force path should act on the ring being fitted, through the approved tooling/support arrangement. A wind-generator bearing’s correct part number and final position do not by themselves prove damage-free installation.

Draw the installation load path

If a ring is being fitted tightly to its seat, resistance occurs at that interface. Applying force through the other ring can route the force across the rolling elements and raceways. Those small contact areas can experience excessive local loading. SKF explicitly warns against this path. The issue is different from normal operating load, which occurs under the bearing’s intended contact and motion conditions.

Match the method to the arrangement

Which ring needs support depends on shaft and housing fits and the assembly sequence. An arrangement with interference at both interfaces can require a different approved method from one with only one tight ring. Bearing type, size, seals and adjacent components also constrain tooling. A general diagram therefore cannot prescribe the appropriate press, heating method or applied force for an unidentified generator assembly.

Request the approved assembly method

Ask the supplier to identify fitted interfaces, supported ring surfaces, tool contact geometry and the equipment-specific inspection/verification basis. Keep any suspected mounting incident distinct from later operating damage. SKF handling guidance explains why the load path matters; it does not authorize MARSTON assembly work or establish a permitted force. Do not hammer a bearing or improvise a press setup from this article. The useful acceptance question is whether the documented method protects the rolling contacts while achieving the specified fit. The assembly evidence should identify any ring that was unsupported during force application. A final smooth rotation check cannot reliably exclude every contact indentation caused by an incorrect earlier mounting load path through the bearing.