Band brake

Belt tensions, shaft load, actuating force and peak contact pressure for a simple lever-actuated band brake, from the brake torque, drum radius, wrap angle and friction coefficient.

✓ validated against legacyoriginal: /calculators/e3_5d.htm
Circumferential force, T₁−T₂ = M/r666.67 N
Band tension ratio, T₁/T₂ = exp(μα)2.85
Band tension, T₁1027.09 N
Band tension, T₂360.43 N
Shaft load, F_a1371.34 N
Max contact pressure, p_max = T₁/(Lr)0.17 MPa
Actuating force, F_i144.17 N

Method & references

  • Euler-Eytelwein capstan friction formula: T₁/T₂ = exp(μα).
  • Band width L is used only for the peak contact-pressure estimate.

The computation is a literal port of the original client-side JavaScript from /calculators/e3_5d.htm. Results are verified equal to the original by an automated golden-master test. No formula has been re-derived or “improved”.

Band brake — Engineering ABC