Cage car for underground coal mine

A cage car for an underground coal mine comprises a tractor, a trailer and a parking joint brake and parking brake and gear joint control device, wherein the parking joint brake and parking brake and gear joint control device comprises a fuel tank, a filter, a hydraulic pump, a tractor parking brake valve, a tractor parking hydraulic cylinder, a tractor parking brake, a hydraulic control air valve, a first air bag, an air control valve, a relay valve, a check valve, a second air bag, an assistor, trailer brakes, a gear selecting reversing valve I, a gear shifting reversing valve II, a gear selecting air cylinder I and a gear shifting air cylinder II. With the adoption of the brake system, the trailer also brakes during parking brake of the tractor, so that the parking braking force is increased greatly; the reliability of parking brake on a ramp of a vehicle is improved; parking brake and gear joint control is achieved, the vehicle in a parking brake state can neither select or shift the gear nor travel, and the problem that a friction plate of a parking brake is prone to abrasion due to the fact that the vehicle puts into gear for travelling in the parking brake state is solved.