Patent ID: 7104370
Filing Date: 2006-09-12
Classification: F16D

Abstract:
1. A drum brake assembly comprising: a rotatable drum having a radially extending inner drum braking surface; a brake shoe of single piece construction and of generally circular loop form mounted within said rotatable drum, said brake shoe having a radially outer face, at least one flange and two separate and opposed ends; a backing plate against which said brake shoe is mounted; a friction lining mounted to said outer face in facing relationship to said radially inner drum braking surface; an actuator positioned between said ends and adapted to enlarge the separation between said ends to thereby cause radial expansion of said brake shoe from an inoperative brake off condition, in which there is clearance between said friction lining and said drum braking surface, to an operative brake on condition, in which said friction lining engages said drum braking surface; an elongate web having a radially outer face which is adapted to form said radially outer face of said brake shoe, wherein said brake shoe flange co-extends with said elongate web and projects radially inward from said elongate web; a positioning arrangement for positioning said brake shoe within said rotatable drum in the inoperative condition against lateral movement into engagement with said rotatable drum braking surface, to provide for complete clearance between said friction lining and said drum braking surface in the inoperative condition, said positioning arrangement including an engagement member associated with one of said brake shoe flange and said backing plate, for engagement with an abutment arrangement associated with the other of said brake shoe flange and said backing plate; said abutment arrangement including a radially inner abutment and a radially outer abutment, wherein said engagement member is arranged for engagement with said radially inner abutment in the inoperative condition of the drum brake assembly to position said friction lining away from said drum braking surface, wherein said engagement member is arranged for engagement with said radially outer abutment when said brake shoe is radially expanded from the inoperative condition through a set running clearance between said friction lining and said drum braking surface to the operative condition of the drum brake assembly, one of said engagement member and said abutment arrangement being formed as a displaceable member which is displaceable radially relative to said brake shoe flange or said backing plate with which it is associated for the purpose of maintaining the set running clearance between said friction lining and said drum braking surface upon lining wear; and a biasing arrangement for facilitating engagement between said engagement member and said abutment arrangement in the inoperative condition by biasing said brake shoe to return to the inoperative condition.