ppt internal expanding shoe brake

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[jaseela123d]

INTERNAL EXPANSION BRAKE




An internal expansion brake consists of two shoes S1 and S2. The outer surface of the shoes is coated with a friction material (usually with Ferodo) to increase the coefficient of friction and to avoid wear of the metal. Each shoe is pivoted at one end around a fixed fulcrum O1 and O2 and a cam is contacted at the other end. When the cam rotates, the shoes are pushed out against the edge of the drum. The friction between the shoes and the drum produces the braking torque and therefore reduces the speed of the drum. Shoes are usually kept in
Off by a spring. The drum encloses the entire mechanism to prevent dust and moisture. This type of brake is commonly used in cars and light trucks.

Now consider the forces acting on the brake when the drum rotates counterclockwise. It can be seen that for the anti-clockwise direction, the left hand shoe is known as the main or main shoe while the right hand shoe is known as the trailing or secondary shoe.

ADVANTAGES OF THE INTERNAL EXPANSION BRAKE: -

(I) It has a simple construction with a small number of pieces. It is cheaper compared to other types of brakes.
(Ii) It is more reliable due to the small number of parts.
(Iii) Requires little maintenance.
(Iv) In an internal expansion brake, a small actuating force can produce a great braking torque.
(V) Provides protection against ingress of foreign particles.