| 摘要 |
In a shoe and drum brake wherein the shoes (14, 15) can move circumferentially of the drum between first and second limit positions and are biased towards the first limit positions, there is provided for transmitting force from an actuator (30) to the shoes a lever (43) or hydraulic device capable of transmitting the force unequally to the shoes. The larger force urges the shoes towards their second limit positions whilst the smaller force urges the shoes towards their first limit positions. During forward rotation of the drum, the shoes remain in their first limit positions and can be applied radially to the drum by movement of the actuator. When the drum is rotating in the reverse direction, the larger force moves the shoes circumferentially of the drum so that the actuator fails to apply the shoes to the drum and establish a braking torque. |
