Patent GB-190812165-A (GB)
Title: Improvements in Automatic Fluid-pressure Brakes for Railway and like Vehicles.
Inventor: FRANCIS JAMES EDWARD
Filed: 1908-06-04
Granted: 1909-08-04
Abstract: 12,165. Francis, J. E. June 4. Brakes.-In a fluid-pressure brake of the Westinghouse type, a graduated release of the brakes is obtained by the use of a release valve, which is arranged to control the exhaust port of the triple valve and is operated either electrically or pneumatically. In the former case, an indicator may be fitted for showing the condition of the electric circuit. This release valve is arranged to be closed when the driver's valve is in either of two positions, situated between the usual running' and full ' release ' positions and termed respectively holding and feed' and charging and graduated re- ' lease' positions. In order to grade down the brake-cylinder pressure, the driver's valve is turned to graduated release,' in which the same conditions hold as for 'full release' with the exception that the exhaust port of the triple valve is closed by the release valve. The driver's valve is then returned to the "running" position, whereupon the circuit is broken and the release valve is opened. When sufficient release has been obtained, the driver's valve is moved to 'holding' position, in which the same conditions obtain as for 'running' position except that the release valve is again closed. By moving the driver's valve alternately to 'running' and ' holding,' the release may be graduated as required. Fig. 1 shows the electrically-operated arrangement. The exhaust 10 from the triple valve 6 is controlled by a balanced piston valve 18, Fig. 5, which slides in a cylinder 19 formed with ports 20. The valve 18 is normally kept open by a spring 22, but is closed by an electro-magnet 16 when the circuit 11, 12, Fig. 1, is completed by the engagement of a switch arm 14, formed as an extension of the handle 15 of the driver's valve 3, with a contact 17. This contact, as shown in Fig. 3, extends between the run- 'ning' position IV and full release' position I, but is engaged by the arm 14 only in the two intermediate positions II, III. In order that the same pneumatic conditions may hold in both positions I, II, the cavity 29 in the valve seating 28, and the cavity 26, Fig. 2, in the valve 23 are extended to provide free communication between the cavity 29 and the train-pipe port 27 in these positions. The usual through port 30 and the cavity 31 for connecting with the equalizing- reservoir port 32, are also extended to provide the usual leading opening to the equalizing-reservoir before the cavities 26, 29 come into communication as the valve is moved to position II. Again, in order to provide the same pneumatic conditions in the positions III, IV, the feed port 24 in the rotary valve is extended to afford communication with the feed port 25 in the seating 28. The cavity 26 in the valve is also extended to give communications between the equalizing-port 50 and the train-pipe port 27. An electric indicator 42, Fig. 1, may be arranged in a branch wire 41, connecting the contact 17 to a third train wire 43, which is provided on each vehicle with a brake controlled bv a switch 40. This switch is closed when the release valve is closed. By this means, an indication as to the state of the electric circuit is given as the driver's valve is moved from lap' position V towards 'release.' A similar indication may be given, prior to applying the brakes, by moving the driver's valve from 'running' to 'holding and feed' position before turning to 'service' position VI. In order to give an mdication after application of the brakes, a second contact 49 may be arranged so that the circuit is closed in 'lap' position. This contact 49 may extend to 'service' position, and in such case the brake cylinder is preferably provided with a pressure-limiting valve. The switch 40 may comprise fixed contacts 44, 45, Fig. 5, arranged within an extension 46 of the valve cylinder 19, and a bridging-piece 47 mounted on the stem of the valve 18. In the case of motor-vehicles operated on the multiple-unit priuciple, where it is usual to place the drivers' valves that are not in use in the 'lap' position, a cut-out switch is provided which may be opened to break the circuit through the contact 49. In the pneumatically-operated arrangement, the exhaust port of the triple valve is connected to a second train-pipe, which is in communication with an additional port 54, Fig. 8, which is formed in the seating of the driver's valve, and is adapted to be connected to the usual exhaust port 35 in this seating by one or other of two additional cavities 55, 56, Fig. 7, formed iu the rotary part of the driver's valve, when this valve is set in the 'full release' and 'running' positions respectively. On the other hand, these cavities 55, 56 are arranged so that the exhaust 54 from the second train pipe is closed for the 'graduated release' and 'holding' positions. In a modification, the port 54 is arranged between the ports 35, 27.