KEVOS® MAKEOS · Mechanics
Band Brake Torque and Lever Force
What band tensions and lever force does this simple band brake need for the braking torque?
Tight and slack band tensions, lever force and maximum lining pressure of a simple band brake from the braking torque, drum size, wrap angle and friction.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Braking torque required | N·m | Torque the brake must hold or absorb, including your service factor. |
| Drum diameter | mm | Drum diameter at the lining. |
| Wrap angle | ° | Angle of band contact on the drum. |
| Coefficient of friction | Lining friction coefficient from the maker (use a conservative value). | |
| Lever length (pivot to applied force) | mm | Distance from the lever pivot to where the force is applied. |
| Pivot to slack-end attachment | mm | Distance from the pivot to the slack-side band attachment (simple band brake with the tight end anchored at the pivot). |
| Band width | mm | Width of the band lining. |
Method and formulas
- Net band force T₁ − T₂ = 2T ÷ D; T₁ ÷ T₂ = e^(μθ).
- T₂ = (T₁ − T₂) ÷ (e^(μθ) − 1); lever force = T₂ b ÷ a.
- Maximum pressure p = T₁ ÷ (r w).
- Example: 400 N·m on a 400 mm drum needs a 64.284 N lever force, with T₁ = 2,642.8 N.
Limitations
- Simple band brake rotating so the anchored end is the tight side; reversing the drum greatly increases lever force.
- Heat dissipation and lining wear are not checked.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Size a band brake for a winch or hoist drum
- Check lever or actuator force
- Check lining pressure
Who it is for
- Design engineers
- Maintenance engineers
- Machine builders
What you get
- Tight and slack tensions
- Lever force
- Maximum lining pressure
Interpreting the result
- Keep peak pressure within the lining maker’s limit and check heat for repeated stops.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2455–2457. Topic reference; no source tables or recommended settings are reproduced.
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