Patent GB-409767-A (GB)
Title: Improvements in and relating to fluid pressure braking apparatus
IPC: B60T15/30
Filed: 1932-11-10
Abstract: 409,767. Fluid - pressure brakes. TOMLINSON, A. V., 65, Victoria Street, London.-(Compagnie des Friens Westinghouse; Sevran, France.) Nov. 10, 1932, No. 31766. [Class 103 (i).] In automatic compressed air brake apparatus of the kind comprising a triple or like valve co-operating with a graduated release valve controlled by the combined action of the auxiliary reservoir or train-pipe pressure and the brake cylinder pressure in opposition to a substantially constant pressure, this latter pressure is arranged to be re-adjusted whenever the triple valve is in the application position and may be the combined brake cylinder and auxiliary reservoir pressures at the value which they have at the beginning of a graduated release operation. The apparatus shown includes the triple valve 1 controlling the graduated application of the brakes, the valve device 3 permitting an initial rapid supply to the brake cylinders and also opening the supply to a " load brake cylinder during the restricted supply stage and the graduated release valve device 2 adapted also to maintain the cylinder pressure against leakage. The valve device 2 comprises a slide valve 16 actuated by diaphragms 18, 19, 20 defining chambers 15, 26, 21, 23. Normally, the train-pipe 6 is connected to the auxiliary reservoir 4 through the chamber 5 of the triple valve 1, passage 35, port 45 of valve 16, chamber 15 and passage 14, which is also connected to the chamber 12 of the valve 1 ; the " light " brake cylinder is connected to the exhaust port 38 by passages 22, 54, ballvalve 47 passages 50, 74, 40, 44, 37<1> ; the " load " brake cylinder 61 is connected to the exhaust port 66 below the piston 46 by the passage 60 and the cock 56 ; the accelerating chambers 75, 76 are connected by passages 77, 79, to the passage 50 thence to the cylinder exhaust port 38. The chambers 21, 15 of the valve device 2 are permanently connected to the " light " brake cylinder and the reservoir 4 respectively by passages 22, 14. When the train-pipe pressure is reduced to apply the brakes, the valves 10, 11 of the triple valve 1 move upwards and connect the train pipe to the chambers 75, 76 by passages 31, 79, 77 and the reservoir 4 to the " light " cylinder by passage 14, chamber 12 of valve 1, passages 81, 82, 50, ball valve 47, passages 54, 22 and also through a restricted passage in the cock 55. When the cylinder pressure is sufficient to depress the spring urged piston 46, the ballvalve seats and the cylinder supply is only through the restricted passage 52 and that in the cock 55. The depression of the piston 46 also opens the supply to the " load " cylinder 61 through passage 64, cock 56, and passage 60. Further, with the triple valves 10, 11, in application position, the chamber 23 of the valve device 2 is connected to the triple valve chamber 12 by the passages 24, 86 and thus to the reservoir 4 and the chamber 26 is connected to the " light " cylinder by passages 27, 84, 85, 86', 54, 22. Upon equalization of the train-pipe and reservoir pressures, the triple valve 11 blanks the cylinder supply port 82 and the passages 24, 27 to isolate the chambers 23, 26. If the pressure in the cylinders and thus in the chamber 21 of the valve device 2 falls by leakage, the valve 16 connects the trainpipe and the accelerating chambers 75, 76 that are connected to it, to the cylinders by passages 31, 43, 42, 22 until the cylinder pressure is restored. This supply from the train-pipe does not affect the triple valve if the drivers valve is adapted to maintain the train-pipe pressure at its reduced value ; otherwise, the triple valve 11 may be moved from lap to application position to connect the reservoir 4 to the cylinders. If the train-pipe pressure is raised to release the brakes the triple valves 10, 11 return to the position shown, the pressure in the reservoir 4 and in chamber 15 of the device 2 rises correspondingly and moves the valve 16 to the position shown to connect the cylinders to exhaust port 38 through the passage 44 of the valve. When the reduced cylinder pressure acting in chamber 21 together with the increased reservoir pressure acting in chamber 15 is again equal to the initial cylinder and reservoir pressures acting in chambers 26, 23 taking into account the diaphragm areas on which the pressures act, the valve 16 moves downwards to a lap position. The areas of the diaphragms are such that although the controlling fluid pressures isolated in the chambers 23, 26 vary with the degree of the brake application the composite pressure which they exert on the valve will be substantially the same. During the release operation the valve 16 will move slightly upwards or downwards to throttle either the passage 34 or 37 to maintain correspondence between the rate of supply to the reservoir and that of the cylinder exhaust. The cocks 55, 56 may be turned to cut out the " load " cylinder and the additional supply passage therein for the " light " cylinder or where no " load " cylinder is provided the passage 60 may lead to an additional exhaust port for the single cylinder which may be rendered operative by a cock such as 56. In initially charging the apparatus, in order to prevent the pressure in chamber 15 of the device 2 from moving the valve 16 upwards thereby cutting off the supply through the passage 35, a valve 103, Fig. 6, is preferably provided adapted to connect the passage 35 to the chamber 23 by passages 102, 24 so that this chamber is also charged. The chamber 107 above a pair of diaphragms 105, 106 secured to the valve 103 is connected to the accelerating chamber 76 by passage 108 the pressure in which closes the valve during an application. The diaphragms also open a valve 113 to connect the chamber 26 of the device 2 to the chamber 76 through passages 27, 116, 108 and thus to exhaust at the final stage of the re-charging operation.