| 摘要 |
The invention relates to a "dual-mode" drum brake for a vehicle, which operates as a service brake in simplex mode and as a parking brake in duo servo mode. The invention also relates to a vehicle including such a drum brake, and to a method for assembling such a drum brake. When operating as a service brake, a first actuator separates two movable ends of the brake shoes while the opposite ends thereof both abut with the housing of a second actuator. When operating as a parking brake, said second actuator separates the two abutting ends from one another, while the movable ends engage one another via a floating inserted element, for example a wear-adjusting rod. All braking or holding torque is transmitted to the plate by the abutment end of a single brake shoe, by engaging, on one side, the housing of the second actuator. The second actuator uses two pistons, one of which is a "spring package", moved by a screw-and-nut system driven by a pre-assembled sub-assembly of gears with axes that are all parallel to the movement of the pistons. The system is driven, on the other side of the plate, by an electric motor-reducer with double planetary gearset sharing a single ring gear. |
