Clutch Torque Calculator
Calculate friction clutch torque capacity from clamping force, friction coefficient, and mean radius.
How it works
- 1Enter the friction coefficient μ (typically 0.3 for dry organic linings), the axial clamping force, the number of friction surfaces, and the mean friction radius.
- 2The calculator applies T = μ · F · n · Rm, where n is the number of friction surfaces and Rm is the mean radius of the friction face.
- 3The resulting torque capacity is displayed in N·m or lbf·ft depending on your selected unit system.
Use cases
- Sizing a single or multi-plate automotive clutch for a target engine torque rating.
- Verifying industrial clutch selection against drive motor output torque requirements.
- Estimating the effect of lining wear or contamination (reduced μ) on clutch slip threshold.
Frequently asked questions
What does the friction coefficient μ represent in a clutch?
μ is the coefficient of friction between the clutch lining and the mating surface. Dry organic linings give μ ≈ 0.3, sintered metal ≈ 0.4, and wet (oil-bath) clutches ≈ 0.1.
Why does a single dry-plate clutch have 2 friction surfaces?
A single disc clamps between the flywheel and the pressure plate, creating one friction face on each side — hence n = 2. Each extra disc in a multi-plate pack adds 2 more surfaces.
How is mean friction radius Rm determined?
For an annular face, Rm = (Ro + Ri) / 2. Example: outer radius 95 mm, inner 65 mm → Rm = 80 mm. With μ = 0.3, F = 1000 N, n = 2: T = 0.3 × 1000 × 2 × 0.080 = 48 N·m.
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