Braking mechanism, brake friction plate wear limit alarm device and mounting method thereof

The invention discloses a braking mechanism, a brake friction plate wear limit alarm device and a mounting method thereof. The alarm device comprises a shell, a slide bar and a power supply, a contactor, an alarm and a damping ring which are arranged in the shell, the shell is directly or indirectly fixed on a brake friction plate, and one end of the slide bar penetrates the outer wall of the shell to be matched with the damping ring; the power supply, the contactor, the alarm and the slide bar are in the same series circuit, and a wheel acts on the first end face of the slide bar when the brake friction plate is close to one side of the wheel to be flush with the first end face, extending out of one end of the shell, on the slide bar and in the process of braking the wheel with the brakefriction plate; with wearing of the brake friction plate, the wheel pushed the slide bar to move to the internal direction of the shell till the brake friction plate achieves wear limit, the second end face of the other end o