Patent GB-657030-A (GB)
Title: Improvements in or relating to telescopic hydraulic shock absorbers
IPC: F16F9/34
Filed: 1948-11-20
Abstract: 657,030. Hydraulic shock absorbers. ARMSTRONG'S PATENTS CO., Ltd., and SMITH. R. Nov. 20, 1948, No. 30213. [Class 108(iii)]  In a telescopic hydraulic shock absorber comprising a pressure cylinder 60 and piston 50, a liquid reservoir A external to the cylinder 60, two similarly directed non-return valves, one 53 in the piston and one 62 fixed with respect to the cylinder 60; and a dependent, liquid discharge pipe 70 communicating with the upper end of the pressure cylinder and extending to below the level of liquid in the reservoir, a non- return valveassembly is located at the lower end of the dependent liquid discharge pipe. The cylinder 60 is held between a head 65 and a spider member 61 forming a seat for the valve 62 and having three legs 61a seated on the end of an outer tube 78 of the reservoir A. The valve 62 is of spring steel and is urged to closing position by a spring 64. The pipe 70 is connected with the cylinder 60 by a passage 71 formed in the head 65. The valve 73 has a conical head which is urged by a spring 76 on to a seat 72 formed in the pipe 70. The seat 72 may alternatively be formed by a constriction in the pipe 70 or by the end surface of the pipe, the valve then being  mounted in a tube of slightly larger bore, Figs. 2, 3 Provisional Specification, (not  shown). Flow through the valve 73 to the reservoir takes place through a port 77 in the wall of the pipe 70. Flutter of the valve 73 is damped by the provision of a piston portion 73a on the valve having a predetermined clearance in the pipe 70, and in addition a passage of small bore may be provided in the plug 75 which closes the pipe 70, Fig. 4, Provisional Specification, (not shown). The valve 53. comprises a cylindrical member slidable within a bore in the piston. The valve 53 has a spherical head which is urged by a spring 56 on to an annular seating, provided by an annular flanged member 55. A washer 57 for positioning the member. 55, is selected according to the valve performance characteristic desired. Valve flutter is damped by flow through the clearance provided between the valve and its bore in the piston, and through a restricted passage 58. A small groove 84 is formed in the spherical head of the valve 53 to permit a bleeding action on small relative movement of the device. A similar groove may be provided in the head of the valve 73. In a modified construction of valve 73, the latter is replaced by a plate valve 92, Fig. 7, mounted in a housing 90 and upwardly urged on to a seat 90a by an annular spring 93 of waved formation. Liquid passing from the pipe 70 is supplied to the face of the valve 92 by means of an annular recess 95 in the housing 90 which is in communication with the pipe 70. The housing 90 is disposed halfway along the length of the reservoir and functions as a baffle. An abutment 94 for the spring 93 is located by a spur edge 90a of the housing but it may alternatively seat on a screw-adjustable plug. A nut 79, Fig. 5, threaded in the outer end of the tube 78, loads packing 80, and a sealing ring 66 which has a series of internal lips and seats on annular spring 67 of waved formation. Liquid passing through the head 65 may drain to the reservoir through a passage 69. In a modified construction, Fig. 1, Provisional Specification, (not shown) the shock absorber mounting eyes 81, 82 are replaced by axially-disposed bolts welded to the end faces of the tube 78 and dust shield 83 respectively. The. bolts carry respective nuts and pairs of annular rubber blocks between which the frame and axle members are clamped.  Operation. On compression, liquid passes upwards through the valve 53, and via passage 71, pipe 70, valve 73, and ports 77, to the reservoir A, valve 62 being'maintained closed. On extension, liquid passes from the reservoir A through valve 62 to the cylinder space below the piston. The valve 53 remains closed and liquid above the piston passes as before via passage 71 &c. to the reservoir.