Industrial Fans, Blowers & Air Movement Equipment worked example
Belt Drive Ratio with motor speed of 880 RPM: a worked example
This worked example runs the belt drive ratio numbers for a tougher week than the baseline: motor speed of 880 RPM instead of the typical 1,750 RPM. Estimate fan shaft speed from motor speed, drive ratio, slip or correction basis, and service multiplier.
The inputs for this scenario
- Motor speed: 880 RPM (the input this scenario stresses; the baseline uses 1,750)
- Drive speed ratio: 0.82 x (held at the documented default)
- Belt slip correction: 0.98 x (held at the documented default)
- Service speed multiplier: 1 x (held at the documented default)
Working through the calculation
- The calculation starts from the formula this tool documents: Estimated fan shaft speed = motor speed × drive speed ratio × belt slip correction × service speed multiplier.
- Result works out to 707 RPM at these inputs, and this is the headline figure for the scenario.
- Base product works out to 707 value at these inputs.
- Multiplier works out to 1 x at these inputs.
- Factor A x B works out to 722 value at these inputs.
How this compares with the baseline
- Against the tool's baseline example, where motor speed sits at 1,750 RPM and the headline result is 1,406 RPM, this scenario comes in 49.71% below the baseline at 707 RPM.
- Use it when selecting or changing drive sheaves to dial in fan speed, or when verifying an existing belt drive against the wheel's safe-speed limit. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.
Results at a glance
- Result: 707 RPM (headline result)
- Base product: 707 value
- Multiplier: 1 x
- Factor A x B: 722 value
Run it with your numbers
- To rerun this with your own numbers, open the live Belt Drive Ratio calculator, set motor speed to your actual value, and adjust the remaining inputs to match your operation.
Last reviewed 2026-05-12.