**Key Force Calculator**

Enter the values of torque, T_{(lbf-in)} and diameter of the shaft, D_{(in)} to determine the value of key Force, KF_{(lbf)}.

**Key Force Formula**

The key force in mechanical contexts often refers to the force exerted by or on a key that is used in a mechanical assembly to transmit torque from a shaft to an attached component, like a gear or pulley.

Key Force, KF_{(lbf)} in pounds-force is calculated by doubling the torque, T_{(lbf-in)} in pounds-force inches and dividing by the diameter of the shaft,D_{(in)} in inches.

Key Force, KF_{(lbf)} = 2 * T_{(lbf-in)} / D_{(in)}

KF_{(lbf)} = key force in pounds-force, lbf.

T_{(lbf-in)} = torque in pounds-force inches, lbf-in.

D_{(in)} = diameter in inches, in.

__Key Force Calculation:__

**Calculate the Key Force required for a torque of 100 lbf-in applied on a shaft with a diameter of 2 inches.**

Given: T_{(lbf-in)} = 100lbf-in, D_{(in)} = 2in.

Key Force, KF_{(lbf)} = 2 * T_{(lbf-in)} / D_{(in)}

KF_{(lbf)} = 2 * 100 / 2

KF_{(lbf)} = 100lbf.

- Assume you need to find the diameter of a shaft that is subjected to a torque of 120 lbf-in, and the required key force is 240 lbf.

Given: T_{(lbf-in)} = 120lbf-in, KF_{(lbf)} = 240lbf.

Key Force, KF_{(lbf)} = 2 * T_{(lbf-in)} / D_{(in)}

D_{(in)} = 2 * T_{(lbf-in)} / KF_{(lbf)}

D_{(in)} = 2 * 120 / 240

D_{(in)} = 1in.