Clearance self-adjustment and overload protection mechanism applied to air pressure disc brake

The utility model discloses a clearance self-adjustment and overload protection mechanism applied to an air pressure disc brake. The mechanism comprises a main adjustment central spindle, a positioning plate assembly, a main shifting block and a shifting block cover, wherein the main adjustment central spindle is connected with the main shifting block through a connecting pin which penetrates through a mounting hole in the main adjustment central spindle; the connecting pin is in clearance fit with the mounting hole in the main adjustment central spindle and is arranged in a counter bore of the main shifting block. The mechanism has a simple structure and ensures self-compensation of a brake clearance after a braking system is worn, and a braking part bears small moment, so that the braking part of the brake is protected, and smooth adjustment to the brake clearance is realized.