Roymech engineering encyclopedia


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The purpose of a brake is to stop or slow down a moving mass generally by converting the kinetic energy into thermal energy using brake pads/shoes/discs etc. The brake surface for friction brakes is made from a material with high coefficient of friction, high strength and good thermal properties. The mass being retarded is generally a rotating inertial load and the brake material is attached to stationary members.

Brake Type

Brake Description Notes
Band Operates by the action of a fixed belt over a rotating cylindrical surface(drum). Action not harsh. Band
Drum Works by bringing curved metal plates, lined with friction material(brake shoes) against an external or internal rotating cylindrical surface. Drum
Disc Disc brake consists of a disc rotating between two friction pads. When the pads are forced together under hydraulic, pneumatic, electrical or magnetic action then the disc is very effectively stopped. Disk
Block/Shoe Probably the first design of brake based on a shoe/block which is forced against the outside of a rotating wheel.  A simple design visible on many old vehicles Block/Shoe
Fluid A smooth progressive brake action resulting from rotating plates, or vanes in a retained fluid. When the fluid is prevented from flowing the viscous resistance retards the rotation.  
This type of brake includes a fixed cylindrical enclosure housing a coil wrapped around a fixed cylinder. Within the cylinder is a cylindrical rotor mounted on the rotating shaft. The annulus between the fixed cylinder and the rotor is filled with magnetic particles. If there is no current in the coil the rotor is relatively free to rotate. On applying a current the particles coalesce and prevent relative movement.  
Shafts driven by an electric motor often using regenerative braking. When the power to the motor is removed. The motor effectively becomes a generator driven by the shaft. The shaft is slowed as the kinetic energy is converted into electical energy. The recovered energy is often stored when used in electric vehicles.