Bearing Selection and Its Relationship with Motor Load

The selection of motor bearings is closely related to the load magnitude. For heavy-load motors, cylindrical roller bearings are typically used at the shaft extension end, while sliding bearings are adopted for particularly large and heavily loaded motors. For ordinary-load motors, especially small ones, ball bearings are commonly used at both ends.

In actual operation, some motors vibrate noticeably under no-load conditions but become smooth after loading. This reflects how well the bearing matches the load. When bearings are designed for heavy loads, their clearance and rigidity may not be optimal under light loads; applying a proper load brings them into their ideal operating range.

In terms of structural configuration, heavy-load motors with rolling bearings typically adopt a two-bearing arrangement with a cylindrical roller bearing at the shaft extension end and a ball bearing at the non-drive end. When strict axial positioning is required, a three-bearing configuration is used—one ball bearing and one cylindrical roller bearing at the shaft extension end, and one ball bearing at the non-drive end. Ordinary-load motors, by contrast, use the simpler two-ball-bearing design.

Bearing size is equally important—its load-carrying capacity must match the actual load and be selected according to operating conditions. Oversized bearings increase cost, while undersized ones are prone to premature fatigue failure. In addition, the transmission method also affects bearing loads: coupling drives impose relatively stable loads with little relation to torque; belt drives are influenced by belt tension and pulley size; gear drives directly bear torque effects.

In summary, motor bearing selection requires comprehensive consideration of load magnitude, structural configuration, transmission method, and operating conditions. Proper matching is essential to ensure long-term reliable motor operation.