GB539227A - Hydraulic shock absorber - Google Patents

Abstract

539,227. Shock absorbers. ELLIOTT, C. K. Dec. 27, 1939, No. 32879. [Class 108 (iii)] A hydraulic shock absorber has a cylinder 12 a piston slidable within and dividing the cylinder into a compression chamber 31 and a rebound chamber 32, an annular transfer chamber 33 surrounding the cylinder, said cylinder being provided through its wall with one or more apertures enabling a substantial amount of hydraulic fluid to flow from the compression chamber into the transfer chamber and thence into the rebound chamber during the initial compressive movement of the absorber, the effective area of escape for the hydraulic fluid from the compression chamber being progressively reduced during progressive movement, the arrangement of the aperture or apertures also permitting quick return of the piston against progressively increasing resistance, and means for controlling the overflow or rebound beyond the normal position so that predetermined resistance is imposed when the piston is moving at a high speed and relatively high resistance is imposed against slower movement of the piston. The aperture or apertures in the wall of the cylinder may comprise a plurality of openings 35, 35<SP>1</SP> spaced along the cylinder, or a single slot largest at its centre and tapering upwardly and downwardly. The means for controlling the rebound may comprise an opening 36 near the upper end of the cylinder obstructed by a spring strip 46 secured at 48 and free at its other end to yield more or less according to the pressure. Alternatively, the piston may have openings through it controlled by a valve backed by a strong spring. A reservoir 34 communicates with the cylinder by a non-return valve 41. A second non-return valve 38 allows fluid to enter the rebound chamber from the transfer chamber, and a third non-return valve 44 allows surplus fluid to escape from the transfer chamber to the outer reservoir.