Industrial Fans, Blowers & Air Movement Equipment worked example

Belt Drive Ratio with motor speed of 4,400 RPM: a worked example

Push motor speed up to 4,400 RPM and the picture changes. This example computes every intermediate figure at that operating point. Use it when selecting sheaves, checking fan RPM, setting belt drive ratio, or comparing motor and drive options.

The inputs for this scenario

  • Motor speed: 4,400 RPM (raised for this scenario; the documented default is 1,750)
  • Drive speed ratio: 0.82 x (unchanged)
  • Belt slip correction: 0.98 x (unchanged)
  • Service speed multiplier: 1 x (unchanged)

Working through the calculation

  • Applying the documented formula (Estimated fan shaft speed = motor speed × drive speed ratio × belt slip correction × service speed multiplier) to the inputs above produces each figure below.
  • At this operating point the engine returns 3,536 RPM for result, the number this scenario is built around.
  • At this operating point the engine returns 3,536 value for base product.
  • At this operating point the engine returns 1 x for multiplier.
  • At this operating point the engine returns 3,608 value for factor a x b.

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 151% above the baseline at 3,536 RPM.
  • It multiplies motor speed by the drive (sheave) ratio, a belt-slip correction, and a service multiplier to estimate fan shaft RPM. The value of this scenario is the size of the gap it exposes: that gap, priced out over a year, is the budget you can justify spending to close it.

Results at a glance

  • Result: 3,536 RPM (headline result)
  • Base product: 3,536 value
  • Multiplier: 1 x
  • Factor A x B: 3,608 value

Run it with your numbers

  • Every input above is editable in the live Belt Drive Ratio calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.