Flat (parallel) key design
Standard key cross-section for a given shaft diameter, and the resulting shear stress, bearing pressure and shaft torsional stress.
Key width, b6 mm
Key height, h6 mm
Keyway depth, t₁3.5 mm
Keyway depth, t₂2.8 mm
Circumferential force, F_s = T/(d/2)10 kN
Shear stress in key, τ = F_s/(L·b)83.33 MPa
Bearing pressure, p = F_s/(h/2·L)166.67 MPa
Shaft torsional stress, τ113.38 MPa
Method & references
- Flat (parallel) key design — standard ISO/DIN cross-section by shaft diameter, with shear/bearing/torsional stress checks.
The computation is a literal port of the original client-side JavaScript from /calculators/key.htm. Results are verified equal to the original by an automated golden-master test. No formula has been re-derived or “improved”.