KEVOS® MAKEOS · Mechanics
Single Shoe (Block) Brake
What lever force does this block brake need, and is it self-energising or self-locking?
Normal force, lever force and shoe pressure of a short single-shoe brake on a drum, for either direction of rotation, with the self-locking check.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Braking torque required | N·m | Braking torque required. |
| Drum diameter | mm | Drum diameter. |
| Coefficient of friction | Lining friction coefficient. | |
| Pivot to applied force | mm | Lever length from pivot to the applied force. |
| Pivot to shoe normal force line | mm | Perpendicular distance from the pivot to the line of the shoe’s normal force. |
| Offset of friction force line from pivot | mm | Perpendicular distance from the pivot to the line of the friction force (tangent at the shoe). |
| Rotation relative to the pivot | choice | Whether friction drags the shoe onto the drum (self-energising) or off it, for this rotation direction. |
| Shoe contact area | mm² | Contact area of the shoe lining. |
Method and formulas
- Friction force = T ÷ r; normal force N = T ÷ (μ r).
- Lever force: self-energising F = N(b − μc) ÷ a; de-energising F = N(b + μc) ÷ a.
- Self-locking when b ≤ μc in the self-energising direction; shoe pressure = N ÷ area.
- Example: 200 N·m on a 300 mm drum needs N = 3,809.5 N and a lever force of 1,417.1 N.
Limitations
- Short-shoe assumption (uniform pressure); long shoes need integration over the shoe arc.
- Heat capacity not checked.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Size a shoe brake for a drum or wheel
- Check the effect of rotation direction
- Avoid unintended self-locking
Who it is for
- Design engineers
- Maintenance engineers
- Machine builders
What you get
- Normal force on the shoe
- Lever force
- Shoe pressure
- Self-locking check
Interpreting the result
- Avoid self-locking geometry unless it is deliberate; it makes the brake grab.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2455–2459. Topic reference; no source tables or recommended settings are reproduced.
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