Patent GB-676418-A (GB)
Title: Improvements in or relating to hydraulic control apparatus
IPC: F16F9/504
Filed: 1948-08-25
Abstract: 676,418. Fluid-pressure servomotor-control systems. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Aug. 25, 1948 [Nov. 20, 1947], No. 22392/48. Class 135 [Also in Group XXXII] A control device for hydraulically actuated apparatus comprises two pressure chambers 108, 109, each directly connected to the device to be actuated and each having two further openings 111, 113 and 115, 117 respectively, the one 111 or 115 being connected to the outlet and the other 113 or 117 being connected to the inlet of a pump or other means 104 for continuously circulating pressure liquid in two closed circuits, the two openings of each chamber being differentially controlled by a pair of shuttle valves 122, 123 which are connected for simultaneous movement as by a rod 124. Fig. 2 shows diagrammatically such a device for application to stabilizing equipment for rail vehicles such as is shown in Fig. 3. The chambers 108, 109 are connected through conduits 102, 103 with a cylinder 129 containing pistons 130, 131 operating through an arm 137 and a shaft 136 on a stabilizing arm 138. The space 134 between the pistons is connected to a neutral space 120 leading to the pump return conduit 105. The pump outlet conduit 106 divides into two branches 106b, 106c leading to the pressure chambers 108, 109. The neutral chamber 120 contains a lever 126 connected to the valve rod 124 and carrying a spring centralised inertia mass 125. Fig. 5 shows in detail an embodiment of the control device suitable for a vehicle stabilizer. It comprises five body parts 201, 202, 203, 204, 205 rigidly connected together. The pressure chambers 108, 109 are formed in sleeves 212, 213 and contain shuttle valves 122, 123 connected to pistons 244, 245 slidable in cylinders 246, 247 mounted in the body part 201. The pump outlet conduits 1066, 106c lead to chambers 206, 207 closed by covers 208, 209. The pistons 244, 245 are rigidly connected by three rods such as 251 passing through bores such as 223. The pressure chambers 108, 109 communicate with the neutral chamber 120 through intermediate pressure chambers 214, 215. Liquid from the latter chambers is continuously bled into the cylinders 246, 247 through orifices 256, 257 and leaves these cylinders through the respective passages 258, 259, recesses 262, 263, and orifices 264, 265, the latter being differentially controlled by pilot valves 266, 267 on a bar 268 rigid with the arm 126 carrying the inertia mass 125. The arm 126 is centred by springs 228, 229 having abutments 232, 233 adjustable on screws 234, 235 carried by the body part 204. A fine adjustment of the balance is obtained by a calibrating screw (not shown). Screws 238, 239 limit the movement of the arm 126. To render the control device responsive to the velocity of the movements to be stabilized, the arm 126 is pivotally connected to a rod 280 bearing pistons 278, 279 movable in cylinders 272, 273 in the body part 204. These cylinders each form part of bleed . passages extending from the respective intermediate pressure chambers 214, 215 to the neutral space 120 and have orifices 276, 282 and 277, 283 for the admission and exit of liquid. Check valves (not shown) are provided between the pressure chambers and the intermediate pressure chambers and also between the latter and the neutral chamber 120. In some cases the arm 126 operates the valves 122, 123 directly. Fig. 3 shows a stabilizer as already described mounted on the bolster 152 of a rail vehicle, the arm 138 being linked to a truck frame 146 which is supported from the axle boxes 142, 143 by springs 144, 145 and itself supports by links 148, 149 a plank 147 bearing the bolster springs 150, 151. Two vertical stabilizers 156, 157 also including a control device according to the invention are arranged between the bolster and the axle boxes. Specifications 7932/05, [Class 135], 644,771, 644,824, and 646,061 are referred to.