Patent GB-190420750-A (GB)
Title: Improvements in and relating to Valves for Fluid Pressure Brakes.
Inventor: AUSTIN WALTER MERVILLE
Filed: 1904-09-27
Granted: 1905-07-20
Abstract: 20,750. Austin, W. M. Sept. 27. Brakes.-Triple valves for fluid-pressure brakes are adapted to maintain the brake cylinder pressure in case of leakage, and also to enable the brakes to be partially released. The casing, made in four parts, supports three diaphragms 1, 2,3, the middle one being larger than the others, which are practically equal. The diaphragms may be corrugated and have strengthening-pieces, and are connected to form one movable member, normally balanced in lap position, as shown, by the train-pipe pressure in the chamber 4 and the pressure in a supplemental reservoir 10 charged by a valve 14 from the auxiliary reservoir, which is charged through a passage 13, shown in dotted lines, and a valve 12. The brake cylinder communicates by a pasasge 7 with the chamber 6, and also through a valve 20, the spindle of which bears against the diaphragm 2, with the chamber 8. The auxiliary reservoir communicates with the chamber 6 through a valve 22, the spindle of which bears against the diaphragm 2. The emergency valve 31 communicates through a valve 34 with the chamber 6, and is held on its seat by a spring 32 strong enough to prevent its movement during service application. On lowering the train-pipe pressure for a service application, the approximately-constant pressure of the supplemental reservoir 10 drives the diaphragms to the left and opens the valve 22 to admit reservoir air to the chamber 6 and the brake cylinder until the excess of the pressure on the larger diaphragm compensates for the fall of train-pipe pressure on the diaphragm 1. Any brake-cylinder leakage that may occur causes in the chamber 6 a fall of pressure which moves the diaphragms as before to restore the pressure. An emergency application reduces the pressure in the chamber 4 sufficiently to cause the diaphragm member to unseat the valve 31, thus allowing air to pass into the chamber 6 and thence to the cylinder. At the same time, the pressure in the chamber 6, acting on a valve 24, along with the reservoir pressure acting through passage 13, 25 on a piston 26 carried by the spindle of the valve 24, unseats this valve and admits reservoir air freely to the brake cylinder to actuate the brakes quickly. On restoring pressure to release the brakes, the diaphragms move to the right and open the valve 20 to vent the brake cylinder to the chamber 8 and the atmosphere through the port 9 shown in dotted lines. Any desired degree of partial release is effected by increasing the trainpipe pressure correspondingly, as the venting of the brake cylinder ceases when the fall of pressure in the chamber 6 allows the pressure in the supplemental chamber to overbalance the increased pressure in the chamber 4. The piston 26 of the valve 24 is cushioned by leathers 27, 28. If the reservoirs are charged by other means than the train-pipe, the valves 12, 14 are dispensed with, any constant force may be used instead of the supplemental reservoir pressure, and pistons may be employed instead of the diaphragms, and slide valves instead of the puppet valves.