KEVOS® MAKEOS · Power Transmission
Caliper Disc Brake Design (Clamp Force, Pad Pressure, Heat)
What clamp force does this caliper disc brake need to stop the inertia in time, is the pad pressure acceptable, and how hot does the disc get per stop?
Design check of a caliper disc brake: the braking torque to stop an inertia in the required time against a load that drives through the stop or helps it, the effective friction radius for uniform wear or uniform pressure, the clamp force for the number of friction faces, pad pressure, friction energy per stop, the disc temperature rise if the disc absorbs the heat, and the stopping angle.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Inertia at the brake disc | kg·m² | Inertia of everything that stops, referred to the brake disc. |
| Speed at the start of braking | rpm | Speed of the disc when braking starts. |
| Required stop time | s | Time within which the load must stop. |
| Load torque at the disc | N·m | Load torque at the disc (friction or gravity). |
| Load during the stop | choice | Whether the load helps the brake or drives through it. |
| Pad outer radius | mm | Outer radius of the pad contact. |
| Pad inner radius | mm | Inner radius of the pad contact. |
| Friction radius basis | choice | Uniform wear (the usual design case) or uniform pressure (new pads). |
| Friction coefficient | Friction coefficient of the pad material. | |
| Friction faces | Number of friction faces (2 for a single disc with a caliper on both sides). | |
| Pad area per face | cm² | Contact area of the pad on one face. |
| Largest pad pressure | MPa | Largest pad pressure for the lining (your value from the maker). |
| Clamp force available | N | Clamp force the caliper can apply. |
| Disc mass | kg | Mass of the disc that takes up the heat. |
| Disc specific heat | kJ/kg·K | Specific heat of the disc (about 0.46 steel, 0.5 cast iron). |
| Largest disc temperature rise per stop | K | Largest temperature rise you accept in one stop. |
Method and formulas
- ω = 2π n ÷ 60; brake torque T_b = J ω ÷ t_s − T_L (load helps) or + T_L (load drives through).
- Effective radius r_e = (r_o + r_i) ÷ 2 (uniform wear) or 2(r_o³ − r_i³) ÷ [3(r_o² − r_i²)] (uniform pressure).
- Clamp force F = T_b ÷ (μ r_e × faces); pad pressure = F ÷ pad area.
- Energy per stop = T_b ω t_s ÷ 2; disc temperature rise = energy ÷ (m c).
- Example: stopping 2 kg·m² from 1000 rpm in 2 s needs 104.72 N·m and 1,496 N of clamp; the disc warms 4.7679 K.
Limitations
- All the heat is taken by the disc mass; pads and hub take some, cooling runs between stops.
- Constant friction coefficient; it falls as the lining heats (fade).
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Size a caliper brake for a machine spindle, winch or conveyor
- Check pad pressure and disc heating
- Compare uniform-wear and uniform-pressure assumptions
Who it is for
- Design engineers
- Maintenance engineers
- Power transmission engineers
What you get
- Braking torque and clamp force
- Pad pressure
- Energy, disc temperature rise and stopping angle
Interpreting the result
- Repeated stops add up: check the cooling time between stops as well as the single-stop rise.
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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Open the Caliper Disc Brake Design (Clamp Force, Pad Pressure, Heat) calculator
