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How to Calculate Gear Ratio and Output Speed

For a simple reduction gearbox, output speed is approximately input speed divided by the transmission ratio. This relationship is also a powerful QA check when reading a gearbox selection table.

Basic equations

i = n₁ / n₂

n₂ = n₁ / i

Where n₁ is input speed, n₂ is output speed and i is reduction ratio.

Example

With 1450 rpm input and ratio 28.37, the theoretical output speed is about 51.1 rpm. Small differences in published tables can result from rounding or the actual rated motor speed used.

How this applies to R, F, K and S gear units

The same engineering principle applies across the CHINFAR four-series platform, but the mechanical layout changes: R is inline/near-inline, F is parallel-shaft, and K/S are right-angle families. Use the principle to define the requirement, then select a configuration within the appropriate family.

Related product families

• R Series Helical Gear Unit
• F Series Parallel Shaft Helical Gear Unit
• K Series Helical-Bevel Gear Unit
• S Series Helical-Worm Gear Unit