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.