# Brake design – calculations

Brakes are machine elements that absorb kinetic or potential energy in the processes of slowing down or stopping a moving part. The absorbed energy is dissipated as heat. Break capacity depend upon unit pressure between the breaking surfaces, the coefficient of friction and ability of the brake to dissipate heat equivalent to energy absorbed. The performance of brake is similar to that of clutches except the clutches connect one moving part to another moving part, where brake connects a moving part to a frame.

• External Shoe or Block Brakes
• Single Block Brake
• Double Shoe Brake
• Internal Shoe Brake
• Band Brake

Heat Generated = p Ac f V / 778 [Btu/min]
Where:
p = average contact pressure
Ac = contact area, inÂ²
f = coefficient of friction
V = peripheral velocity of drum

 Material Max Temp Â°F f fPmax, psi Metal on metal 600 0.25 200 Wood on metal 150 0.25 70 Leather on metal 150 0.35 25 Asbestos on metal in oil 500 0.40 50 Sintered metal on cast iron in oil 500 0.15 400