Patent GB-368701-A (GB)
Title: Improvements relating to fluid pressure braking apparatus
IPC: B60T13/46
Filed: 1930-10-31
Abstract: 368,701. Fluid - pressure brakes. BROWN, D. F. and WESTINGHOUSE BRAKE & SAXBY SIGNAL CO., Ltd., 82, York Road, King's Cross, London. Oct. 31, 1930, No. 32805. [Class 103 (i).] Vacuum brakes comprise a regulating valve adapted to produce an initial quick inshot of air to the lower chamber of the brake cylinder and controlled by the pressures in the upper and lower chambers of the brake cylinder. The valve may control aquick inshot of train pipe or atmospheric air or both. The regulating valve comprises a ball valve controlled by a diaphragm influenced by a spring, the action of which may be adjusted, and the pressures in the upper and lower chambers of the. cylinder and a controlling the connection between the train pipe and the lower chamber. When the pressure in the lower chamber has increased to a predetermined extent on brake application the ball valve closes and the subsequent supply from the train pipe to the lower chamber takes place through a restricted port. In a modification an additional restricted part is provided in the regulating-valve between the upper chamber of the valve and the train pipe, controlled by a ball valve for use in releasing the brake and the usual release valve is combined with this valve. Also the upper chamber of the brake cylinder is connected through a restricted port to the lower chamber of the regulating valve. In a further modification the diaphragm operates a valve member having an inner seated area subject to the pressure in the compartment 1 when the valve is closed. In another modification the regulating valve permits a quick inshot of atmospheric air the entrance of which to the cylinder takes place through a port 69, Fig. 6, and avalve 67 operated by a diaphragm 63 influenced by train pipe pressure and the pressure in the upper chamber 1 of the regulating valve and a diaphragm 70 influenced by the train pipe pressure in a chamber 71 through a passage 72. The operation of this valve resembles that of the valve 21, Fig. 2. The regulating valve may be provided as shown in Fig. 6 with an additional valve member 74 closed subsequently to the valve 56. A quick inshot of train pipe air is first produced through the valve 56 which then closes giving a restricted supply through an opening 58. The valve 67 opens simultaneously and produces a quick inshot of atmospheric air through the passage 65, the valve 74 then closes and the final supply of atmospheric air takes place through a restricted opening 76. The port 58 may be substituted by the port 72 the chamber 71 being connected to the passage 75. The regulating valve, Fig. 2, produces a quick inshot of atmospheric air to the brake cylinder and with a slight fall of train pipe pressure, a local increase in train pipe pressure and comprises a primary valve 21 which opens the connection to the atmosphere and a secondary valve 35 which terminates the quick inshot. The train pipe, upper and lower brake cylinder chambers are connected to passages 15, 40, 48 respectively. Normally, air is exhausted from these chambers through ball valves 42, 18 and the train pipe. The chambers above and below abutments 19, 33 of the primary and secondary valves respectively, are also exhausted by the passages shown and these valves assume the position shown. On brake application pressure increases in the train pipe passage 15 and by means of a restricted port 16, in the passage 48 and lower chamber of the brake cylinder until the abutment 19 is raised and lifts the ball valve 21 to produce a flow of atmospheric air to the brake cylinder through passages 22, 23 and restricted ports 36, 37. The chamber 28 above the abutment 19 is simultaneously isolated by the engagement of a gasket 30 with a seat 31. Train pipe air also flows through a restricted port 27 to the brake cylinder. If however the increase of train pipe pressure is slight atmospheric air may flow from the passage 48 to the train pipe producing a local increase of train pipe pressure. When the pressure in the lower brake cylinder chamber has increased to a predetermined extent the abutment 33 is depressed closing valve 35 and cutting off the air supply through the port 36 and also connecting the chamber 28 to the lower brake cylinder chamber through passages 45, 46. With a slight increase of train pipe pressure the abutment 19 is accordingly returned to its lower seat and by means of the valve 21 cuts off the supply of air to the lower brake cylinder chamber. With an increase of train pipe pressure more rapid than the increase of lower cylinder chamber pressure the local increase of train pipe pressure is not obtained and the abutment 19 is moved from its upper seat to close the valve 21 but has a tendency to float between its upper and lower seats and air continues to flow through the ports 16, 27 to the brake cylinder until the pressure in the lower brake cylinder chamber and the chamber 28 has attained a pre-. determined value when the abutment 19 is moved to its lower seat and equalization of pressure takes place through the port 16. If a very heavy increase of train pipe pressure is made the abutment 19 is not at once moved from its upper seat. Port 37 may be dispensed with. An additional brake cylinder for braking a loaded vehicle may be connected to the chamber 28. When the abutment 33 engages the lower seat 39 it positively cuts off the upper chamber passage 40 from the passage 48 in order to prevent leakage. The outer areas 26 of the abutments 19, 33 are not subject to the operating pressure until the abutments are raised from the seats 25, 44 respectively in order that the abutments may then move quickly.