Output Shaft Speed Calculator

Calculate output shaft speed in rpm from input speed and gear ratio, gear teeth or multiple stages, or reverse it to find the input speed or ratio.

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Output Shaft Speed Formula

The following formula is used to calculate the output shaft speed.

Variables:

• OSS is the output shaft speed (RPM)
• ISS is the input shaft speed (RPM)
• GR is the positive speed-magnitude ratio ISS/OSS; for one fixed gear pair it equals driven teeth/driver teeth.

To calculate the output shaft speed, divide the input shaft speed by the gear ratio.

What is Output Shaft Speed?

Output shaft speed is the rotational speed of a gearbox output. For a fixed ratio without slip, its speed magnitude is input speed divided by the positive input/output ratio. One fixed gear pair uses driven teeth divided by driver teeth; a multi-stage train uses the product of the actual stage ratios. Efficiency changes the torque and power estimate, not this kinematic speed relation. Rotation direction, slip, planetary configurations and equipment ratings require their actual mechanisms and data; this estimate does not establish safe operating limits.

How to Calculate Output Shaft Speed?

The following steps outline how to calculate the Output Shaft Speed.

1. First, determine the input shaft speed (ISS) in revolutions per minute (RPM).
2. Next, determine the positive input/output speed ratio (GR). For one fixed gear pair use driven/driver teeth; multiply the actual ratios of successive fixed stages.
3. Next, gather the formula from above = OSS = ISS / GR.
4. Finally, calculate the Output Shaft Speed (OSS) in RPM.
5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

input shaft speed (ISS) = 1500 RPM

gear ratio (GR) = 3.5