| 摘要 |
A drum brake assembly which includes a rotatable drum having a radially inne r drum braking surface and a brake shoe (102) of single piece construction and of generally circular form mounted within the drum and against a backing pla te (111). The brake shoe includes friction lining (107) and at least one flange (126) projecting radially inwardly. The brake shoe (102) has positioning mea ns for positioning the brake shoe (102) within the drum in an inoperative condition against lateral movement into engagement with the drum braking surface, to provide for complete clearance between the friction lining (107) and the drum braking surface in the inoperative condition. The positioning means includes engagement means (131, 132) for engagement with abutment mean s (130). The abutment means (130) includes radially inner and outer abutments (134, 135) and the engagement means (131, 132) is arranged for engagement wi th the radially inner abutment (134) in the inoperative condition of the assemb ly to position the friction lining (107) away from the drum braking surface, an d with the radially outer abutment (135) when the brake shoe (102) is radially expanded to the operative condition of the assembly. One of the engagement means (131, 132) or the abutment means (130) is formed as a displaceable member (133) which is displaceable radially relative to the brake shoe flang e (126) or backing plate (111) for the purpose of maintaining the set running clearance between the friction lining and the drum braking surface upon lini ng wear. Engagement between the engagement means (131, 132) and the abutment means (130) in the inoperative condition is facilitated by biasing means (13 6) which biases the brake shoe to return to the inoperative condition. The biasing means may include the shoe undergoing resilient distortion to functi on as a return spring or it may include bias springs which act on the shoe.</SD OAB> |
