A control valve includes a diaphragm with a flow path with a predetermined cross-section from a brake pipe to a first side of the diaphragm and another flow path having another predetermined cross-section from a second side of the diaphragm to atmosphere. A dump valve prevents flow from the brake pipe to atmosphere. A method for operating a control valve includes supplying brake pipe air to a first side of a diaphragm through a flow path having a predetermined cross-section and permitting or preventing reference air flow to atmosphere through another flow path having another predetermined cross-section. The method further includes supplying reference air to a dump valve that prevents brake pipe air flow to atmosphere.

An air control valve, including a main valve body, a main valve cavity communicates with an auxiliary air cylinder, an air inlet channel communicates with a train pipe, the air inlet channel communicates with the main valve cavity, and an air exhaust channel communicates with the main valve cavity; a sliding valve, which attaches to the main valve cavity, a communicating channel communicates with the air inlet channel, the communicating channel communicates with the air exhaust channel, a brake inflation channel communicates with the main valve cavity, and the brake inflation channel communicates with a brake cylinder; and a shut-off valve, a shut-off valve body is provided with a shut-off valve cavity, a shut-off valve core is disposed in a driving cavity and separates the driving cavity into an auxiliary air cavity and a brake cavity, the auxiliary air cavity communicates with the auxiliary air cylinder, the brake cavity communicates with the brake cylinder, the air exhaust cavity communicates with the air exhaust channel, and the shut-off valve core has an air outlet position for communicating an air inlet of the air exhaust cavity with an air outlet of the air exhaust cavity and a closing position for separating the air inlet of the air exhaust cavity from the air outlet of the air exhaust cavity.