A belt drive is acceptable only when belt pull, sheave position and alignment remain within the motor shaft and bearing limits. Correct belt tension can still overload a motor if the sheave is too far from the bearing or the selected diameter produces excessive radial force.
Fix the duty before choosing a feature
A useful review begins with the driven equipment, the supply and control arrangement, the mechanical interface and the site condition. Review the complete belt geometry and transmitted load, not only the belt supplier’s tension value. If one of those inputs is still open, mark it as an assumption instead of hiding it inside a general note.
This matters because the motor is only one part of the drive train. The equipment owner defines the duty and acceptance criteria; the motor supplier confirms what the offered design can deliver. Keeping those responsibilities separate makes technical questions easier to close.
The minimum technical review
| Step | Review point | Why it matters |
|---|---|---|
| 1 | Sheave position on the shaft | Record effective belt centreline, hub engagement, key fit and distance from the motor bearing. |
| 2 | Belt pull and service condition | Calculate or obtain the radial load for starting, running and expected process variation. |
| 3 | Sheave alignment and tension | Check offset, angular alignment, belt condition and tension after the run-in inspection. |
Typical failure paths
- Moving the sheave outward for clearance. Extra overhang increases shaft bending and bearing reaction even if transmitted power is unchanged.
- Retensioning without checking alignment. Misaligned sheaves can create uneven belt load and misleading tension readings.
Information the supplier needs
The approval record should be short enough to use and detailed enough to audit. Keep the following items with the decision:
- belt and sheave selection data
- motor allowable radial-load confirmation
- cold and run-in alignment and tension records
Where a limit comes from the manufacturer, request confirmation for the exact motor and revision. Where it comes from the plant or driven equipment, identify the responsible engineering owner. Photographs and field measurements are useful supporting evidence, but they should not replace a controlled drawing or test record.
Decision rule
A belt drive is acceptable only when belt pull, sheave position and alignment remain within the motor shaft and bearing limits. Apply that rule to the complete operating envelope, not only the rated point. If the required evidence is missing, leave the item open and name what must be supplied before manufacture, shipment or energisation.