Nominal torque-transfer screen
Parallel key / keyway stress
Inputs
Nominal shaft diameter at the key engagement.
Known steady torque applied to the single keyed connection.
Nominal rectangular key width at the shear plane.
Nominal rectangular key height; half height is used in the simplified bearing area.
Fully engaged key length under the stated direct-load model.
Results
Shaft tangential force
10,000
Nominal key shear stressτ
16.667
Nominal key bearing stressσb
50
Ft = 2T/D; τkey = Ft/(wL); σbearing = Ft/[(h/2)L]
A first-pass number, not a code check, certification, or approval. Read the method and its limits below. What this is and is not.
Nearby: Axial response · Beam deflection & reactions · Elastic stability · Solid-shaft torsion
Method
Formula, when it applies, and when it does not
Calculate tangential force and nominal parallel-key shear and bearing stress from shaft, key, and torque geometry.
Ft = 2T/D; τkey = Ft/(wL); σbearing = Ft/[(h/2)L]
When
- Single rectangular key
- Full stated engagement
- Nominal direct stress
Don’t
- This is a single rectangular-key, steady-torque direct-stress screen. It excludes key/keyway standards selection, root stress concentration, shaft weakening, fit clearance, hub deformation, multiple keys, load sharing, assembly, fatigue, material allowables, lubrication, transients, and design approval.
Shigley's Mechanical Engineering Design — keys, pins and shaft connections