Enter the total torque transmitted by the shaft and the diameter of the shaft into the calculator to determine the key force.

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## Key Force Formula

The following equation is used to calculate the Key Force.

KF = T*2/D

- Where KF is the key force (lbf)
- T is the torque applied to the key (lbf-in)
- D is the diameter of the shaft (in)

## What is a Key Force?

Definition:

A key force is the total force, including direct and shear force, acting on a key during operation.

## How to Calculate Key Force?

Example Problem:

The following example outlines the steps and information needed to calculate the Key Force.

First, determine the torque applied to the key . In this example, the torque applied to the key is found to be 50 lbf-in.

Next, determine the shaft diameter. For this problem, the shaft diameter is found to be 4 in..

Finally, calculate the Key Force using the formula above:

KF = T*2/D

KF = 50*2/4

KF = 25 lbf