Clutch / brake torque arithmetic
Friction-interface torque
Inputs
User-entered interface coefficient for the stated condition; no material or condition is inferred.
User-entered normal clamp force on the stated friction interface.
User-entered effective mean friction radius; pressure distribution is excluded.
Positive integer number of active friction surfaces in the stated model.
User-entered reference torque for literal ratio arithmetic only.
Results
Declared friction-interface torque
152.32
Friction torque / declared demand
1.2693
—Friction torque minus declared demand
32.32
Tfriction = z·μ·Fa·rm; ratio = Tfriction / Tdeclared
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 friction-interface torque and its ratio to a torque demand from coefficient, clamp force, mean radius, and active surfaces.
Tfriction = z·μ·Fa·rm; ratio = Tfriction / Tdeclared
When
- Uniform stated friction coefficient
- User-entered axial clamp force
- User-entered mean friction radius
Don’t
- This is a stated uniform-friction torque relation for a user-defined clutch or brake interface. It excludes temperature, energy absorption, wear, pressure distribution, actuation, engagement dynamics, material selection, capacity, safety, and approval.
Shigley's Mechanical Engineering Design