The invention discloses a locomotive and an air-controlled
backup brake control system thereof. The air-controlled
backup brake control system comprises a
backup brake valve, a balancing air cylinder, a
relay valve, an air-controlled shut-off valve and a
cut-out cock, wherein an input opening of the backup brake valve communicates with the first end of the
cut-out cock, and an output opening of the backup brake valve communicates with an air opening of the balancing air cylinder; the air opening of the balancing air cylinder and a pre-control opening of the
relay valve communicate with the first end of the
cut-out cock; and the second end of the cut-out cock communicates with a main air
pipe; an air source opening of the
relay valve communicates with the main air
pipe, and an outlet opening of the
relay valve communicates with an air inlet of the air-controlled shut-off valve; the air outlet of the air-controlled shut-off valve communicates with a
train pipe, and a control opening of the air-controlled shut-off valve communicates with the first end of the cut-out cock; when the cut-out cock is opened, the first end and the second end of the cut-out cock are communicated, or else, the first end communicates with the outside; and when a preset
atmospheric pressure is generated at the control opening of the air-controlled shut-off valve, the air inlet and the air outlet of the air-controlled shut-off valve are in communication, or else, the air inlet and the air outlet of the air-controlled shut-off valve are not in communication. According to the air-controlled backup
brake control system disclosed by the invention, when being under an ordinary condition, the balancing air cylinder is under a decompression condition, so that the situation that when pure air backup braking is performed, the locomotive has a stable braking effect is guaranteed, and the relieving situation is avoided.