Abstract: Valves for maintaining brake cylinder pressure in freight car brake equipment are provided. A valve includes a first diaphragm defining a first side and a second side, and a second diaphragm defining a first side and a second side. The valve further includes a first port for receiving pressure from one of an emergency reservoir or a control volume, the first port in fluid communication with the first side of the first diaphragm; a second port for receiving pressure from a brake pipe, the second port in fluid communication with the second side of the first diaphragm; and a third port for receiving pressure from a brake cylinder, the third port in fluid communication with the second side of the second diaphragm.

Abstract: A pneumatic brake valve unit for a rail vehicle, includes: a main device (20) designed for selective control of a communication path between a brake pipe connector (18) and either an atmospheric exhaust line (19) or an auxiliary reservoir connector (16), such that the pressure at the brake pipe connector (18) is k times the difference between the pressure at a control reservoir connector (14) and the pressure at a main brake pipe connector (12), k being a proportionality factor; and a reset device (23) designed for selective control of a communication path between an air discharge member (54) and the control reservoir connector (14) between an open position when the pressure at the brake pipe connector (18) is atmospheric pressure and a closed position when the pressure at the brake pipe connector (18) is above atmospheric pressure.

Abstract: Valves for maintaining brake cylinder pressure in freight car brake equipment are provided. A valve includes a first diaphragm defining a first side and a second side, and a second diaphragm defining a first side and a second side. The valve further includes a first port for receiving pressure from one of an emergency reservoir or a control volume, the first port in fluid communication with the first side of the first diaphragm; a second port for receiving pressure from a brake pipe, the second port in fluid communication with the second side of the first diaphragm; and a third port for receiving pressure from a brake cylinder, the third port in fluid communication with the second side of the second diaphragm.

Abstract: A pneumatic brake valve unit for a rail vehicle, includes: a main device (20) that selectively controls a communication path between a brake pipe connector (18) and either an atmospheric exhaust line (19) or an auxiliary reservoir connector (16), such that the pressure at the brake pipe connector (18) is k times the difference between the pressure at a control reservoir connector (14) and the pressure at a main brake pipe connector (12), k being a proportionality factor; a cut-off valve (21) that controls a communication path between the main brake pipe connector (12) and the control reservoir connector (14); an accelerator device (22) that controls a communication path between the main brake pipe connector (12) and an air discharge member (19); and a driving pilot (39) which is common to both the valve (21) and the accelerator device (22) and which controls their respective communication paths.

Abstract: A pneumatic brake valve unit for a rail vehicle, includes: a main device (20) designed for selective control of a communication path between a brake pipe connector (18) and either an atmospheric exhaust line (19) or an auxiliary reservoir connector (16), such that the pressure at the brake pipe connector (18) is k times the difference between the pressure at a control reservoir connector (14) and the pressure at a main brake pipe connector (12), k being a proportionality factor; and a reset device (23) designed for selective control of a communication path between an air discharge member (54) and the control reservoir connector (14) between an open position when the pressure at the brake pipe connector (18) is atmospheric pressure and a closed position when the pressure at the brake pipe connector (18) is above atmospheric pressure.

Abstract: A pneumatic brake valve unit for a rail vehicle, includes: a main device (20) that selectively controls a communication path between a brake pipe connector (18) and either an atmospheric exhaust line (19) or an auxiliary reservoir connector (16), such that the pressure at the brake pipe connector (18) is k times the difference between the pressure at a control reservoir connector (14) and the pressure at a main brake pipe connector (12), k being a proportionality factor; a cut-off valve (21) that controls a communication path between the main brake pipe connector (12) and the control reservoir connector (14); an accelerator device (22) that controls a communication path between the main brake pipe connector (12) and an air discharge member (19); and a driving pilot (39) which is common to both the valve (21) and the accelerator device (22) and which controls their respective communication paths.