Patent GB-191508374-A (GB)
Title: Improvements in and relating to Fluid Pressure Braking Apparatus.
Inventor: TURNER WALTER VICTOR
IPC: B60T8/18
Filed: 1915-06-05
Abstract: 8374. Turner, W. V. Oct. 1, 1914, [Convention date]. Fluid-pressure.-The effective auxiliary-reservoir volume, and thus the braking - pressure with given reduction of trainpipe pressure, is adjusted automatically according to the load. For this purpose, vertical movement of a car on its bearing- springs due to variation in load is arranged to control, by mechanism 5, Figs. 1 and 6, associated with the car body and spring plank, and connexions 4, 3, 2, the position of a slide valve 37, Figs. 2 and 3, whereby one or more of a series of chambers A, B, C, D is put into communication with the ordinary auxiliary reservoir 12. To permit adjustment only when the car is standing, the closing of the car doors is arranged to put the adjusting-mechanism out of action. A valve device, also adjusted according to the load, for predetermining the maximum pressure obtainable in the brake cylinder is provided. Whenever the car doors 20, 21, 22, Fig. 1, are opened, a differential piston 31, 32, Figs. 2 and 3, is operated to move the slide valve 37 to the right by the pin 36. Shutting of the doors causes the piston 31, 32 to move the slide valve 37 to the left as far as an abutment 48 on a sliding bar 38. The position of the bar 38 is determined by the load by means of the device 5, Figs. 1 and 6, comprising a rack 111 working in a part 108 fixed to the car body and adapted to be moved by the vertical displacement of the car body when in contact with a rod 116. The rod 116 has a piston 114, the cylinder 113 of which is fixed to the spring plank of the car. Air is admitted to the cylinder 113 to contact the members 116, 111 only when the car doors are open. The movements of the rack are transmitted by pinion 110 and connexions 3, 4 to a bar 2, Figs. 1 and 3, having a cam or block 43 engaging the lever 40, 41 connected to the bar 38. The cam 43 is so shaped as to give the correct amount of movement to the bar 38, according to the type of bearing-springs employed. The bar 38 is locked in position when the car doors are closed, by pawls 52, 53 formed on pneumatically-operated pistons 50, 51. The car doors effect the operations ascribed to them above by means of an electromagnetically-controlled double-beat valve 64, the circuit of which is broken (see Figs. 1 and 2), when the doors are closed, so that fluid from the chamber 61 of a slide valve 60, which constantly communicates with the main reservoir 6 by a pipe 7, is admitted also to the piston chamber 59 by passages 65, 66. The slide valve 60 thus assumes the position shown in Fig. 2, whereby the chamber 30 of the differential piston communicates with a supplemental reservoir 14 by passages 63, 101, 17, and piston chamber 29 communicates with small chamber by the slidevalve 60. The piston chamber 113 of the device 5, Fig. 6, at the same time communicates with exhaust port 121 by pipe 115 and slide-valve cavity 120, and fluid is admitted to the piston chambers of the locking-pawls 52, 53 by the passages 57, 66. When the car doors are opened (Fig. 3), the double-beat valve 64 connects the passage 66, and consequently the pawl and slide-valve piston chambers 52, 53, 59, to exhaust 68. The differential piston chambers 29, 30 being now respectively connected to the supplemental reservoir 14 and exhaust port 121, this piston moves to the right with the main slide valve 37. Fluid is also then admitted from the valve chamber 61 to the chamber 113 of the device 5, Fig. 6, which is thus put into operative position, and as the pawls 52, 53 are disengaged, the sliding bar 38 is set to a new position if the load varies, an the slide valve 37 is moved to the corresponding position when the doors are again closed. The slide valve 37 is adapted, according to its position, to connect any combination of the chambers A, B, C, D with the auxiliary reservoir 12 by way of the passages 123, 124, space 125 in the slide valve 60, passage 126, and pipe 16, and, except when a chamber is so connected, to connect it by space and passages 33, 35, 34 and pipe 17 with the supplemental reservoir 14. A suitable application and release valve 10, Figs. 1 and 5, includes a slide valve 79 adapted to connect the reservoirs 12, 14 and subsidiary chambers A .. D with the train-pipe 11 for charging, and in service applications, to connect the reservoir 12 and the chambers A .. D open to it, with the pipe 18 leading to the brake cylinder .9. In emergency applications, the reservoir 14 is also connected with the brake cylinder by pipe 19 by the operation of the second slide-valve device 87. Limiting-valves, described below, are interposed at 127, 127<a>, Fig. 2, between the pipes 18, 19 and the brake cylinder. The reservoir 12 and connected chambers A .. D are charged by connexions 82, 81, 94, 83, and the reservoir 14, and inoperative chambers A .. D by passages 95, 96 and also by passage 159. The brake-cylinder passage 84 is shown as open to exhaust port 157. In an application, the passage 84 is open to the valve chamber 78 as usual. The valve chamber 87 of the emergency device, and through it the chambers 147, 148, are normally maintained at train-pipe pressure by passages 82, 90, 97 past check valve 98, and the valve 91, which controls the connexion between the supplementalreservoir and brake-cylinder passages 92, 93, is held in closed position by this pressure through passage 154. In an emergency application, the auxiliary slide valve 89 first moves and admits pressure beneath the quick-action valve 145 through passage 146, and the consequent venting of the train-pipe by passage 90 and orifice 161 effects the prompt and complete movement of the main valve 88 against the action of the spring stop 162. In this position the pressure beneath the valve 91 is vented through passages 154, 151 and port 153, and the valve therefore drops to the open position. The chamber 147 is at the same time connected by passage 165 with the chamber 146 of the quickaction valve, which is, however, provided with a leak-off port 166 to effect closure after an interval. The pressure in chambers 87, 148 is meanwhile permitted to leak off through passage 152, and when it falls below that of the train-pipe and the spring stop 152, the valve 88 is returned. In service applications, to prevent emergency movement of the valve, the chamber 87 is vented by passages 163, 164 and port 153, to equalize with train-pipe pressure by movement of the auxiliary slide valve 89. The brake-cylinder pressure is prevented from receding a maximum, dependent on the load, by limiting-valve devices 127, 127<a>, Fig. 2, interposed in both the service and emergency passages 128, 18, and 139, 19 leading from the valve 10. These comprise, in each case, a spring piston valve 127 controlling, in the case of the service device, a passage 137 connecting passages 128 with brakecylinder passage 129 and adapted to be opened by the fluid pressure. A connexion 133 between the valve chamber 136 and passage 129 is cut off by a valve 132 when the pressure acting on diaphragm 130 is sufficient to overcome the spring 131, thereby effecting closure of valve 127 by allowing equalization of the pressures on the two sides thereof. The limiting-valve device 127<a>, 132<a> is similarly arranged with respect to the emergency passage 139, 19. The tension of the springs 131, 131<a> is adjusted according to the load, by the cross-head 135 and connexions 156 with the lever 40, Fig. 3. The tension of the spring 131<a> of the emergency device is always greater than that of the service device. In release, the fluid flows from the brake cylinder past the check valve 138. In the event of failure of the limiting-valves, the fluid flows to the brake cylinder by way of the valve 140.