Drum brake apparatus including parking brake operating in dual servo mode and associated vehicle and method of assembly

Abstract

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.

Description

[0001] The invention relates to a drum brake for road vehicles, especially for light or heavy road vehicles. [0002] The drum brakes provide service braking as well as parking or emergency braking, operating according to different modes. [0003] In service braking mode, the first actuator separates the two moving ends of the block, while their opposite ends both abut the anchor, performing a "simplex" type of work. [0004] In parking brake mode, a second actuator, fixed to the floor, moves the two stop ends away from each other, while the moving ends are pressed against each other via a floating intermediate element, which provides, for example, wear adjustment the connecting rod. Any braking or holding torque transmitted by the drum to the blocks is transmitted by the stop end of the individual blocks, which is pressed against the housing of the second actuator. Thus, the second actuator performs a "dual servo" type of function, providing a significantly improved force wit...

AI Technical Summary

Problems solved by technology

This mode is significantly more efficient, but has other disadvantages such as being more difficult to adjust and wearing unevenly

It is not widely used as a service brake

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