Patent GB-1064697-A (GB)
Title: Fluid pressure brake control apparatus with accelerated release after service application
Inventor: KIRK WALTER BLANCHARD
IPC: B60T15/18
Filed: 1964-05-04
Abstract: 1,064,697. Air braking system. WESTINGHOUSE AIR BRAKE CO. May 4. 1964, No. 18391/64. Heading F2F.  A fluid pressure braking system includes a brake pipe, a brake cylinder, an auxiliary reservoir, a brake controlling valve responsive to reduction of brake pressure in the normally charged brake pipe to effect supply of fluid from the reservoirs to the brake cylinder to effect application of the brakes and responsive to restoration towards normally charged pressure in the brake pipe to effect release of the fluid pressure from the brake cylinder to release the brakes, and accelerated release mechanism comprising a normally closed first valve operative to effect a local increase in brake pipe pressure, fluid responsive means subject opposingly to brake pipe pressure and auxiliary reservoir pressure comprising a movable abutment and responsive  to an increase or excess of brake pipe pressure to initiate a brake release following a brake application for opening the said valve to establish communication between the emergency reservoir and the brake pipe, thereby to accelerate of pressure therein and accelerate the restoration of the valve device to brake release position in which fluid under pressure is released from the brake cylinder resulting in release of the brakes.  Operation.-To initially charge the system pressure air supplied to the brake pipe 1 passes through pipe 7 and strainer 94 to chamber 33, through passage 63 and ports in the graduating and service valves 17, 18 to chamber 34, volume chamber 75, emergency reservoir 3 and auxiliary reservoir 4, the flow to the latter being retarded by the restricted port 110 in valve 18 to allow more air to flow to the rear of the train. If pressure in chamber 34 increases than that in chamber 33, the valve moves rightwards against spring 42 to connect passage 63 with restricted passage 108 to provide a retarded recharge. In either position of the valve the brake cylinder 2 is connected to atmosphere through emergency valve 12, passages 67, 140, 66, and the normally open pressure retaining valve 86, while chamber 87 below the diaphragm of quick service limiting valve 73 is connected to atmosphere, the unseated valve member 144 keeping quick service passage 62 at atmospheric pressure. Brake pipe pressure also acts on both sides of the diaphragm of a valve 72 and at chambers (113, 135, Fig. 3, not shown) associated therewith. Service braking.-A small reduction of brake pipe pressure causes graduating valve 17 to move leftwards relative to valve 18, first cutting off reservoir 3 and chamber 33 from chamber 34. As spring 54 is overcome valve 17 moves to initial quick service position where passages 63, 64 are connected to allow brake pipe air to flow to quick service volume chamber 79 to give a sudden limited reduction in brake pipe pressure, a reduction then continued at a slower rate through plug 81. Further leftward movement of valves 17 and 18 connects passage 150 and its choke 151 to passage 63 to continue quick service venting until valve 18 laps passage 63. Air under pressure then flows from chamber 34 and reservoir 4 to brake cylinder 2 by way of passage 145 uncovered by valve 17, passage 67 and emergency valve 12. Passages 62, 63 are next connected by choked passage 154, air flowing at a slow rate from the brake pipe to cylinder 2 by passage 62, quick service limiting valve 73, passages 67a, 67 and valve 12. Air is also supplied to chamber 34 to maintain pressure in the auxiliary reservoir 4 as long as leakage therefrom does not exceed the capacity of the choke 154b. At a predetermined brake cylinder pressure diaphragm 88 rises to cut off the quick service flow from pipe 1 to the cylinder 2. Service lap.-When the pressure in chamber 34 falls sufficiently by flow through passages connected to passage 145, valve 17 moves back to the service lap position with shoulder 159 abutting the left end of valve 18 and cut-off passage 145. Release of brakes.-Air under pressure supplied to the brake pipe then flows to chambers 33 and 57 as described before, the choke 155 and the closed limiting valve 73 causing a lower pressure to appear in chamber 34 and the valve moves rightwards. Pressure air is thus supplied to chamber 34 and auxiliary reservoir 4 from the fully charged emergency reservoir. Due to choke 108 little air is taken from the brake pipe. Restriction 110 in valve 18 limits flow between reservoirs 3 and 4 to ensure that the pressure in chamber 34 is less than that in chamber 33 to prevent unintentional movement of valves 17, 18. Brake pipe pressure acts in cavity 116 of valve 72 to move the valve leftwards against auxiliary reservoir pressure in chamber 117, thus opening the valve (113) to connect the emergency reservoir to the brake pipe by way of valve 136. This accelerates brake release since all the air supplied to the brake pipe does not have to be conveyed from the locomotive along the pipe from car to car. The Specification also describes the manner in which the valve 72 performs the function of a release insuring valve.