Patent GB-346831-A (GB)
Title: Improvements relating to fluid pressure braking apparatus
IPC: B60T15/30
Filed: 1930-01-18
Abstract: 346,831. Fluid pressure brakes. TOMLINSON, A. V., 65, Victoria Street, London.- (Compagnie des Freins Westing- house; 23, Rue d'Athenes, Paris.) Jan. 18, 1930, No. 1811. [Class 103 (i).] Fluid-pressure braking apparatus having graduated application and release by means of a control valve having a constant pressure control chamber or its equivalent, comprises a valve device adapted to open the brake cylinder to atmosphere to enable the final venting of the brake cylinder to be effected, when the pressure in the brake cylinder has been reduced to a predetermined low value relative to the pressure in the auxiliary reservoir, this venting being independent of the graduated release action. The valve device comprises a diaphragm 2, the chamber 4 above which is in permanent communication with the brake cylinder and the chamber 6 below, with the auxiliary reservoir by a passage 7. Brake cylinder pressure, on brake application, moves the diaphragms and a slide valve 8 to close a connection 16, leading to the triple valve exhaust, from an atmospheric outlet 18. When brake cylinder pressure has fallen to a predetermined low value, on brake release auxiliary reservoir pressure moves the slide valve 8 up again to reconnect ports 16,18. Ports 13, 14 leading to the control chamber of the triple valve and the train pipe respectively are also reopened to the chamber 6. A modification is shown in which pistons are used in place of diaphragms. Further modifications have the atmospheric chamber 20 arranged between the chambers 4, 6 and are shown both with diaphragms and pistons. The modification shown in Fig. 5 uses a poppet valve 25 carried by an arm 26 pivoted on the diaphragm 2 and having an upturned end 27 adapted to engage the casing when the diaphragms rise on brake release and open the valve to connect the brake cylinder chamber 4 to atmosphere through the hollow spindle 19 of the diaphragms. Poppet valves 29, 30 are opened by the diaphragm 3 at this stage to connect passages 13, 14 from the control chamber and the train pipe respectively to the chamber 6. In a further modification using poppet valves the atmospheric chamber 20 is arranged between the chambers 4, 6 and the valve 25 is opened by the diaphragm 3 and the valves 29, 30 by an extension of the spindle 19. A further modification shows a complete brake apparatus. Pressure fluid admitted by the triple valve 71 to the brake cylinder 80 also depresses a double beat valve 122 closing a connection 124to atmosphere and moving a piston 106 and a slide valve 108 to cut off a passage 118 leading to exhaust chamber 88 of the graduated release valve 81 from an atmospheric outlet 120. When brake cylinder pressure falls to a predetermined low value a spring 107 returns the piston 106 and the valve 108 to connect the chamber 88 and the passage 89 leading to the triple valve exhaust to atmosphere. Valve 108 also controls passage 113 connected to the passage 101 leading from the triple valve slide valve chamber 75 to the chamber 86 of the graduating exhaust valve and also passage 116 leading to the chamber 86 connected to the auxiliary reservoir 87 which is charged through these passages. A connection 111 from the chamber of valve 108 is adapted to supply the control reservoir 85 of the graduating exhaust valve. Diaphragms 82, 83 of the graduating valve are raised and a valve 102 in the passage 101 allowed to close in release position. Reduction of auxiliary reservoir pressure in the chamber 86 on brake application allows the diaphragms to move down and hold the valve 102 open and close a valve 96 which controls the triple valve exhaust through a passage 89. The valve 96 effects a graduated release by variation of auxiliary reservoir and brake cylinder pressure in the chambers 86, 88 respectively. If the pressure in the reservoir 85 falls below auxiliary reservoir pressure the central portion of the diaphragm 82 contained in a box 92 will move upwards raising a valve 93 thus recharging the control reservoir from the auxiliary reservoir.