GB998742A - Improvements in or relating to telescopic shock absorbers - Google Patents

Abstract

998,742. Hydraulic shock-absorbers. AUTOMOBILOVE ZAVODY LETNANY, NARODNI PODNIK. March 29, 1963 [March 29, 1962], No. 12516/63. Heading F2S. A telescopic hydraulic shock-absorber provided with hydraulic limiting stops at both ends includes a piston which is formed of two parts 20, 21 providing a chamber 14 for an annular relief valve 51 and which is slidable within a working cylinder 1 closed at each end by a more robust cylindrical stop extension 2, 10 or 4, 10 of smaller diameter and mounted within an outer cylindrical jacket 31 to form an annular fluid space 32 communicating at its upper end through openings 40B in the stop extension 4, 10 with a reservoir 37 and, through a base valve assembly 3, 60, with a compression chamber 18 below the piston 20, 21. The atop extensions 2, 10, and 4, 10 co-operate with corresponding braking-stop rings 7, 7 which are mounted, for limited axial movement, on supporting extensions 9, 8 of the piston 20, 21: An intermediate full-size portion 12 of the piston carries a seal 13 and is located between reduced end portions 24 which are substantially of the same diameter as the stop rings 7, 7 for introduction into the stop extensions 2, 10 and 4, 10. Each stop ring, split to form a closable axial slot 27, is urged by a spring 30, away from the corresponding flat seating surface of the piston 20, 21, into engagement with the enlarged head 28 of the corresponding supporting extension 9 or 8, through-flow passages being provided through bores 29 in the supporting extensions and openings 48 between the inner ends of the rings 7, 7 and the corresponding seating surfaces of the piston 20, 21. The valve plate 51, having small bores 52, controls passages 50, 22, 49 through the lower piston port 20. The upper end of the working cylinder space 17 communicates with the annular space 32 through a cylinder wall. opening 41 which is shielded by a deflector 57 and which has as wedge-shaped slot 55 extending from its upper edge. During operation, when a stop ring 7 commences to enter the cylindrical portion 10 of a stop extension 2, 10 or 4, 10 bevelled surfaces 23, 11 respectively on the ring 7 and stop extension co-operate so that the ring becomes radially compressed to progressively close the slot 27 at the same time the ring is gradually urged down on to the corresponding flat seating surface of the piston 20, 21 to progressively close the opening 48 and the bores 29 so that asubstantial full hydraulic lock is provided. A slight leakage past a piston-rod seal 39, 54 occurs in the upper stop a corresponding leakage in the lower stop being by way of small bores 52B in a foot valve plate 3. The reservoir 37 is formed by a tube 38 which spaces a closure 34, for the upper end of the outer casing 31, from the upper stop extension 4, 10 the closure having a filling plug 36 and a drain plug 47 being provided in a lower closure 33.