Patent GB-348697-A (GB)
Title: Improvements in and relating to fluid pressure braking apparatus
IPC: B60T15/30
Filed: 1930-02-17
Abstract: 348,697. Fluid-pressure brakes. WESTINGHOUSE BRAKE & SAXBY SIGNAL CO., Ltd., 82, York Road, King's Cross, London.-(Assignees of Farmer, C. C. ; 7008, Thomas Boulevard, Pittsburg, U.S.A.) Feb. 17, 1930, No. 5233. Convention date, March 16, 1929. [Class 103 (i).] A fluid-pressure control valve influenced by the pressure in the train-pipe and in a constant pressure control reservoir is arranged to control the operation of a repeater valve device controlling the supply of fluid to and from the brake cylinder, the only fluid acting on the repeater valve being supplied through the control valve. The control valve comprises a slide valve 13 controlled by diaphragms 16 .. 19 and the repeater valve comprises a slide valve 36 controlled by pistons 37, 38. A " light " brake cylinder 7 and a " load " cylinder 8 are provided. The control valve is influenced by pressure fluid from the trainpipe 11 in a chamber 32 above the diaphragm 16 and by the pressure fluid from the control reservoir 9 in the chamber 23 between diaphragms 18, 19 by means of the passages shown. On charging the apparatus train-pipe pressure fluid passes by passage 53, 58 and ball valves 54, 55 to the auxiliary reservoir 10 and the slide valve chamber 35 of the repeater valve and also moves the slide valve 45 by means of the diaphragm 43 to charge the control reservoir 9, pressure fluid in which recloses this valve. Pressure fluid from passage 58 also passes by cavity 60 of slide valve 13 and passages 61, 62 to the piston chambers 39, 41 of the repeater valve. The pressure fluid in the chamber 23 forces down the diaphragm 19 against the springs 31 and when the pressures in chambers 32, 23 are equal the diaphragms 16, 17, 18 will be moved down by the spring 33 to the position shown in which the passage 62 and the chamber 41 is connected to exhaust outlet 65 so that the repeater valve is moved to the release position shown by the pressure fluid in the chamber 39. In this position the brake cylinder 7 and chamber 69 between the diaphragms 16, 17 are connected to exhaust 68 through passage 70 and cavity 67 as is also a quick service bulb 66. On reduction of train-pipe pressure for brake application the slide valve 13 moves up and connects the chamber 41 by passages 62, 58 to the auxiliary reservoir and connects the chamber 39 by passages 61, 65 to exhaust so that the repeater valve moves to its opposite end position to apply the brakes until the brake cylinder pressure in chamber 69 moves the valve 13 to lap position in which both the chambers 39, 41 are connected to the auxiliary reservoir and the repeater valve is held in lap position by the spring stops 40, 42. When in brake application position the repeater slide valve 36 supplies the brake cylinders by passages 85, 86 from the chamber 35 which is connected by passage 56 and ball valve 84 to the auxiliary reservoir 10. The quick service bulb 66 is connected to the trainpipe by passages 53, 63 and cavity 67 to produce local reduction in train-pipe pressure. In lap position ports 68, 70, 86 are closed and the brakes are maintained applied. The " light " brake cylinder 7 is supplied from passage 86 past a quick unshot valve 4 and also through a restricted passage 89 in the change over valve 6. Pressure fluid also flows through a restricted passage 91 until it forces down the piston 71 of the " load " cylinder cut-in valve device 5, cutting off the " load " brake cylinder 8 from exhaust port 2 and supplying it with pressure fluid through the passage 91. The control and repeater valves move to make good any leakage. The train-pipe maintains 'the brake cylinder pressure when the auxiliary reservoir has reached the same pressure as the train-pipe. If the pressure of the control reservoir falls by leakage more than a predetermined amount the springs 31 force the follower 24 against the diaphragm 18 and thus compensate for the reduction in control reservoir pressure. To release the brakes, train-pipe pressure is increased and the control and repeater valves move to release position the brake cylinders exhausting through passage 70 cavity 67 and exhaust port 68. When the load cylinder pressure is reduced to a predetermined degree the piston 71 moves up and the final exhaust of this cylinder takes place through exhaust port 82. Graduated release can be obtained by graduated increases of train-pipe pressure, under the controlling influences of the brake cylinder pressure chamber 69. The " load " cylinder is cut off by rotating the valve 6 which also substitutes a more restricted passage 95 for the passage 89 so that it will require substantially the same time to apply the brakes when the " light cylinder is alone employed as when both cylinders are used. Specification 320,861, [Class 103 (i), Brakes &c.], is referred to.