Patent GB-1029556-A (GB)
Title: Improvements in or relating to hydraulic buffers
IPC: F16F9/18
Filed: 1962-11-13
Abstract: 1,029,556. Hydraulic shock - absorbers. HOUDAILLE INDUSTRIES Inc., and MIDLAND-ROSS CORPORATION. Nov. 13, 1962 [Dec. 8, 1961], No. 42917/62. Heading F2S. An hydraulic buffer comprises a working cylinder 49 which communicates with a reservoir 63, a piston 77 slidable in the cylinder 49 and connected to a piston-rod 13 projecting beyond one end of the cylinder, and a separately formed cylindrical extension 12 concentrically connected to said one end of the cylinder, the piston-rod extending slidably through the cylindrical extension 12 and fluid-sealing and bearing surfaces being formed on the piston-rod engageable with the cylindrical extension. As shown in Figs. 3-5, the rod 13 of the piston 77 workable in the hydraulic cylinder 49 located by flange members 51, 55 in the reservoir housing 10 having an upper enlargement 64 is guided in the extension tube 12 which is welded at 58 to the flange 55 and which projects, with a seal 54, into the outer end of the cylinder 49, the inner machined surface of'the tube 12 cooperating with a closure bearing 104 which is carried by the rod 13 and which is backed-up by a resilient seal 107 with backing rings 112 and packing and compression plugs 109, 114 respectively constrained between a series of springs 115 and a retainer ring 111, the springs 115 being accommodated in recesses 117 in a further bearing bushing 118 which is provided with a groove 122 and a bore 123 which leads to a radial passage 125 communicating, through a ball valve arrangement 129, 131 with the hollow interior 87 of the piston-rod 13. Oppositely-coiled spring units 15-17 extend, in compression, between the flange 55 and a flange on a swivelling mounting on the outer end of the piston-rod 13, a further swivelling mounting 11 being secured to opposite end of the housing 10. During a compression stroke the piston 77 pumps fluid through openings in a metering tube 69 secured in an opening 70 in the flange 51, and through corresponding radial passages 72, 73 respectively in the flange 51 and the end wall 40 of the housing 10 and into the reservoir 63 fluid passing into the space behind the piston 77 through the metering tube 69 and into the rod interior 87 and then, through radial passages 88 and branched axial bores 89 past a floating plate valve 91. A bleed and metering orifice 75 is provided in the upper edge of the flange 51. On rebound the valve 91 closes the bores 89, but for a small radial groove 93 across the end face of the piston, make-up fluid passing from the reservoir 63 through the tube openings 68 and through the tube 69 and the hollow rod space 87 to the radial passages 88 which have flow areas 94 opening into the front face of the piston 77 and controlled by a floating plate valve 97. During very high pressures slight distortion of the cylinder 49 may permit fluid to by-pass seals 99, 101 between the cylinder 49 and the piston 77 and the flange 51 respectively. The reservoir 63 has a filling opening closable by a plug 65 and an annular inspection window 66. In a modification, Figs. 10, 11 (not shown), the reservoir 217 communicates with the space 251 between the piston-rod 214 and the extension tube 229 through a port 250 in an end closure plate 226 which may not be in fluidtight engagement with the corresponding end of the cylinder 212. Radial ports 243 in a closure plate 222 at the other end of the cylinder 212 connect the metering tube 213 to the reservoir 217, the ports 243 being provided with branch ducts 244 which lead to the cylinder space 241 and which are controlled by a spring-loaded plate valve 245. A metering orifice 249, e.g. of  inch diameter, is provided in the wall of the cylinder 212 and fluid may flow from the hollow interior of the rod 214 through a passage 261 and past a check valve 260 to the area behind the piston 211. A bearing 258 with a spring- pressed resilient seal 256 and retainer 253 carried by the rod 214, seals the outer end of the annular space between the latter and the extension tube 214. In a further modification, Figs. 12, 13 (not shown), the seal at the end of the extension tube is subjected to return-stroke damping pressure and the metering holes are formed in the wall of the working cylinder. Also the piston is loosely attached to the pistonrod in a manner to act as a check valve, a tie-rod assembly being located between the opposite ends of the cylinder and the piston-rod.