Centrifugal clutches and brakes

Centrifugal brakes

Besides centrifugal clutches, centrifugal brakes are becoming increasingly important.A decisive advantage of centrifugal brakes over conventional brakes is that they operate without an external power supply.The brake, mounted on a shaft, starts to brake a drive shaft at a defi ned speed. Centrifugal force causes the fl yweights to lift from the hub so that their linings contact the inside diameter of the brake drum. This action creates a braking torque.As soon as the speed of rotation of the system falls, the tension industrial springs return the fl yweights to their initial positions.It is a fundamental principle of centrifugal brakes that they cannot brake a system to a standstill, i.e. the system speed searches for an equilibrium condition between the speeds determined by load torque and braking torque.Although centrifugal brakes are governed by the same technical principles as centrifugal clutches and also use similar components, brakes call for additional investigation of their conditions of use.The most important principle governing the use of centrifugal brakes is: FRICTION PRODUCES HEAT Centrifugal brakes convert mechanical energy into heat, which is generated between the lining and the brake drum, and mostly heats up the latter. The temperature distribution illustrated above on a sectioned brake drum clearly shows the higher heating of the drum in the region over the fl yweights.The amount of heat generated depends on various factors: • Transmitted brake torque • Brake speed • Duration of the braking operation • Size of the friction surface • The mass of the brake drum that has to be heated

For further technical advice and explana-tions, see page 6 et seq. For special designs that deviate from this principle, see page 34 et seq.

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