Patent GB-682974-A (GB)
Title: Improvements in or relating to vibration dampers of the friction disc type
IPC: F16F7/04
Filed: 1950-02-23
Abstract: 682,974. Friction-type vibration-dampers. ANDRE (COMPONENTS), Ltd., and BARNETT, L. H. Feb. 23, 1951 [Feb. 23, 1950], No. 4676/50. Class 108 (iii). In a vibration damper of the type in which one or more friction plates are mounted to slide but not rotate on an operating shaft journalled in at least one wall of a casing in which one or more friction plates (interposed between the shaft friction plates) are mounted to slide but not rotate, means for forcing the friction plates into contact comprise a pressure member, one face of which acts on the end friction plate, and a lever member having one end acting on the adjacent end wall of the casing, an intermediate point of the lever acting on the pressure member, and its other end bing acted on by an adjusting member. In the construction shown, the shaft 6 has a portion 10 of rectangular section which co-operates with a correspondingly-shaped aperture in a shaft friction plate 13. This aperture may be wider than the shaft portion 10 in order to provide a degree of lost-motion between the plate 13 and the shaft 6. A second shaft friction plate 14 is riveted to a flange 16 of the shaft 6. Friction plates 17, 18 and 19 have spaced peripheral lugs (not visible in Fig. 2). Each trio of corresponding lugs on the respective plates 17, 18, 19 are engaged by a common axially-extending bolt rigid with the casing. The bolt passes through a rubber bush mounted in an aperture in the corresponding lug, Fig. 4 (not shown). Friction discs 23 of wood or other suitable material are disposed between the friction plates. A pressure plate 24 bearing on the friction plate 19 is in the form of a disc having a diametral ridge 24a which bears on the ridge 25a of a similar plate 25. One point of the periphery of the plate 25 bears on the cover-plate 3, and a diametrically-opposite point is acted upon by an adjusting-screw 28 to select the pressure applied to the friction discs and plates. Co-operating flats or pins and notches may be provided to prevent rotation of the plates 24, 25. The pressure is also adjustable by the action of a rubber pressure chamber 34, the interior of which is connected by a pipe 35 (Fig. 5) with a source of adjustable hydraulic pressure such as a sealed collapsable chamber adjacent the driver of the vehicle. The casing 1 may be filled with viscous oil through a filler 31. A duct 11 provides for equalization of pressure in the spaces 30, 30a on axial movement of the shaft 6 consequent with variation of friction plate pressure. The shaft 6 may alternatively be held from movement in an axial direction, the plate 14 then being axially slidable on the shaft. Instead of the shaft portion 10 being of rectangular cross-section, it may be serrated. When the shock absorber is applied to suspensions employing wishbone links the shaft 6 may extend through both ends of the casing and carry an operating arm at each end. In an alternative arrangement for providing for lost-motion between a friction-plate and the casing or shaft, the plate comprises two or more concentric annular parts. One part is formed with a radial projection which engages a slot of greater peripheral length formed in the adjacent peripheral edge of the adjacent annular part. The degree of lost motion may be different for different plates. According to the Provisional Specification, . the friction plates may be urged together by adjustable spring pressure and the disc 24 may be a spring lever. The casing friction plates may be formed with peripheral grooves or projections co-operating with corresponding grooves, projections or slots formed in the casing. The slots may be longer than the projections in order to provide for lostmotion. Where a friction-plate is formed in two or more annular parts as described above, the radially innermost part may also have lostmotion relative to the shaft.