Key dimensions: Parallel keys are most commonly used. The key length should be less than about 1.5 times the shaft diameter to ensure a good load distribution over the entire key length when the shaft becomes twisted when loaded in torsion.

Stresses: Since compressive stresses do not cause fatigue failure, the bearing pressure is limited by the material yield strength YS of the weakest part, commonly the hub. The maximum shear stress in the key and the maximum torsional shear stress in the shaft can be derived from the yield strength of the shaft material.

We also have an Metric Keyway Calculator.

To use this calculator, input your Torque, Shaft Diameter and Key Length values. Select your units as required.

Keyway Calculator