Patent GB-823649-A (GB)
Title: Improvements relating to compressed fluid braking apparatus particularly for railwayvehicles
IPC: B60T8/32
Filed: 1957-09-30
Abstract: 823,649. Fluid pressure brakes. COMPAGNIE DES FREINS ET SIGNAUX WESTINGHOUSE. Sept. 30, 1957 [Oct. 1, 1956], No. 30504/57. Class 103 (1). A compressed fluid braking apparatus, for railway vehicles, of the " graduated release" kind in which the supply of fluid to the brake cylinder is controlled by a movable pressuresensitive means subject to brake pipe pressure, control reservoir pressure and brake cylinder pressure, comprises a fluid-pressure loading device which when operative imposes on the pressure-sensitive means additional bias tending to cut-off the brake cylinder supply, fluidoperated means which when operated restricts the rate of flow of fluid to the brake cylinder,' and speed-responsive means effective .when the. vehicle speed falls below a predetermined value to cause the supply of pressure fluid to operate the loading device and pressure-restricting means. The distributer valve, of usual type, communicates with control reservoir 3, auxiliary reservoir 4 and brake cylinder 2, and includes a service stack 1 with a loading device 15, a quick service volume 6 and its valve 7, a combined charge and quick-service exhaust valve 8, control reservoir fast-charging valve 9, a loading device 10 for valve 8, and an electromagnetically-operated valve 11 controlled by a circuit having centrifugal switch driven by the vehicle axle. When train speed is insufficient to close the centrifugal switch, valve 11 is opened by a spring and a decrease in train pipe pressure is effective in chamber 37 of stack 1 connected to chamber 35 of quick-service valve 7 and passage 36, to move the stack 1 upward to unseat valve 33 to connect auxiliary reservoir with brake cylinder 2 through passage 39, valve 33, passage 32, passages 23 in flowrestricting device 16, valve 26 and passage 40; the fluid also passes to chamber 41 of stack 1 and chamber 34 of loading device 15 to exert a force tending to lower the stack and close valve 33 when a predetermined pressure has been reached in brake cylinder 2. Further, the fluid acts on piston 18 of device 16 to move slide 22 to seat valve members 26, 27, whose valve stems are forced down cams 24, 25 of slide 22 by springs 28, 29 and the supply of pressure to brake cylinder 2 from the auxiliary reservoir is through restricted passage 30 in member 26. With the stack in the brakerelease position the brake cylinder 2 is exhausted to atmosphere via passage -43, valve 27, passage 44, opening 45 in stack 1, axial bore 46 and passages 47 and 39. For greater braking pressure needed at high speeds, the centrifugal switch is closed by axle speed and valve 11 operated to move member 12 to cut-off communication of the brake cylinder with chamber 34 of loading device 15 and chamber 20 of flow-restricting device 16, these being exhausted to atmosphere. On opening of valve 33 by stack 1 the pressure fluid is supplied to chamber 41 and brake cylinder 2, the stack remains raised since no returning pressure is created in chamber 34. The movable parts of device 16 are moved to the right due to no brake pressure in chamber 20, so that cams 24, 25 lift the valve members 26, 27 to enable the brake cylinder 2 to be supplied from auxiliary reservoir 4 through unrestricted passages 23 in slide 22 instead of the restricted passage 30. During release, the communication of brake cylinder 2 to atmosphere is past member 27 and so is unrestricted. A piston and a diaphragm may be substituted for the diaphragm of loading device 15 and the piston 18 of the device 16, respectively.