|Key dimensions: Parallel keys are most commonly used.
The key and key seat cross section are ISO standardized. 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.
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.
Calculator for fatigue strength >>