GB387383A - Improvements relating to fluid pressure braking apparatus - Google Patents

Abstract

387,383. 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.) Aug. 5, 1931, No. 22189. Convention date, Aug. 6, 1930. [Class 103 (i).] In a triple valve on brake application, venting of the train pipe is effected by the movement of the graduating valve before the main valve is moved and the movement of the main valve effects a further venting of the train pipe. The fluid from the train pipe is vented to chambers one of which is vented to atmosphere in lay position. A retaining valve can be operated to retain a certain degree of pressure in the brake cylinder and certain of the venting chambers. The initial movement of the triple valve piston 7 on brake application closes the feed passage 33 for the auxiliary reservoir 4 and a spring plunger 16 on the triple valve stem 11 engages a flange 14 on the main valve. Further reduction of train-pipe pressure compresses the flanged spring 13 and moves the graduating valve 10 to connect the train pipe to a venting chamber 58 by a cavity 39 and passages 46, 45, 44, 37, 36. The graduating and main valves are then moved together to connect the auxiliary reservoir to the brake cylinder by passages 49, 48, 34, to cut off the chamber 58 from the train pipe and to connect the train pipe to venting chambers 59, 60 by passages 46, 50, 51 and 46, 54, 53, 52, 41 respectively to produce further venting of the train pipe. Restrictions in the passages to chambers 59, 60 shows the venting and ensures that it is proportional to the time the triple valve is in service position. When auxiliary reservoir pressure is slightly below train-pipe pressure the graduating valve moves to lap position in which brake cylinder supply is cut off and the third venting chamber 60 is vented to the atmosphere through passages 41, 52, 53, 55, 56. The restriction in the passage 41 shows this venting so that the amount of venting depends on the time the triple valve is in the lap position. When the brakes are released the valve takes up the position, shown in the Figure in which the brake cylinder and chamber 58 are connected to atmosphere through passage 20 and the retaining valve 51 the chamber 59 through non-return valve 32 and a valve 27 to the chamber 58 and the chamber 60 to an atmospheric opening 40. When the valve 5 is operated by a handle 19 to retain a certain degree of pressure in the brake cylinder fluid pressure is also retained in chamber 58 and this pressure acts on a diaphragm 22 to hold closed the valve 27 and thus retain fluid pressure in the chamber 59. Thus upon a successive brake, application fluid will not be vented to the chamber 59 and flow to the first chamber will be reduced, thus preventing an excessive reapplication of the brakes. A ball valve 57 prevents back flow from the chamber 59 to the train pipe. A spring 18 or spring 13 move the piston from the usual packing ring on brake release to expose the full area of the piston 7 to train-pipe pressure.