INTERNAL EXPANDING BRAKE

INTERNAL EXPANDING BRAKE 

An internal expanding brake  consists of two shoes s 1  & s 2 as shown fig. .The outer surface of the shoes are lined with some friction material to increases the coefficient of friction and to prevent wearing away of the metal .Each shoe is pivoted at one end about a fixed fulcrum o, 1 & o, 2 and made to contact a cam at the other end. When the cam rotates the shoes are pushed outwards against the rim of the drum . The friction between the shoes and the drum produces the braking torque and hence reduces the speed of the drum .The shoes are normally held in off position by a spring as shown fig. The drum encloses the entire mechanism to keep out dust and moisture .This type of brake is commonly used in motor cars and light trucks .