Patent GB-637291-A (GB)
Title: Improvements in shock absorbers
IPC: B60G15/14
Filed: 1945-05-18
Abstract: 637,291. Hydro-pneumatic shock-absorbers. GRUSS, L. R. May 18, 1945, No. 12563. [A Specification was laid open to inspection under Sect. 91 of the Acts, May 23, 1946.] [Class 108 (iii)] In a shock-absorber comprising two telescopically movable members housing a floating ram, one end of which operates against gas under pressure in a cylinder within one of the members while the other end operates against liquid in a cylinder in the other member, which latter cylinder carries a device to restrict the flow of liquid therefrom, the device has an opening through which the ram reciprocates. In the construction shown, the shock-absorber comprises telescopic cylinders 10, 11 secured to two relatively-movable members such as a wing and a landing-wheel of an aircraft, and housing a ram 13 having at its upper end a piston 12 slidable in an auxiliary cylinder 8, secured to the cylinder 10, thus forming a combined air and liquid cushioning device, the lower end of the ram being slidable with clearance in a further liquid-containing cylinder 9 within the cylinder 11. Flow of liquid from and into the cylinder 9 on entry and withdrawal of the ram 13 is controlled by a valve 27 formed underneath with clearance ribs 29 and freely movable vertically in a recess 26 in a partition 25 fixed in the cylinder 11. Liquid flows out of the cylinder 9 through restricted clearance spaces between the ram and the valve 27 and a nut 28 closing the recess, and into the cylinder through the clearance space between the ram and nut, around the valve and through the valve ribs 29. The auxiliary cylinder 8 is secured to the head 16 of cylinder 10 by a shank 61 and has a partition 66 containing a passage 67 controlled by a downwardly-seating check valve 68 and a much smaller permanentlyopen passage 69. A quantity of liquid A is introduced through a nipple 70 into the cylinder 8 above the piston 12 and, when the ram is in the lowermost position, liquid is introduced into the cylinder 9 and above the partition 25 by means of a pipe 80, until it overflows through transverse passages with an axial space 74 in the piston and its extension 14, and thence past a spring-pressed valve 78 through transverse passages 76 with the space inside the cylinders 10, 11 above a partition 40 fixed in the cylinder 11. An outwardly-seating check valve 36 on the cylinder 10 controls flow of atmospheric air through a passage 35 into the annular space formed by co-operating shoulders on the cylinders 10, 11. These shoulders limit the extended position of the shock-absorber and separate on compression of the device. The annular space also communicates through a passage 38 with a closed air cell 37, the arrangement preventing the formation of a vacuum in the annular space. Packing in the form of rubber or like rings 20, 21, 45, 63, 64 of circular cross-section is used where shown, the grooves in which the rings are seated being large enough to allow some movement of the rings. Above the groove for the ring 21 are provided a further groove 23 and an oil recess 22 for lubricating both the ring 21 and the ring 20. Operation.-When there is no load on the shock-absorber, the parts assume the position shown, with compressed air and a layer of oil in the cylinder 8 above the piston 12, with the space in the cylinder 10 above the partition 40 and outside the cylinder 8 filled with compressed air through a valve 50, with the ram cylinder 9 filled with oil to the level B above the partition 25 and with the space between the oil-level B and partition 40 filled with compressed air. On compression, as the cylinder 11 is forced into the cylinder 10, oil in the cylinder 9 is forced through the restricted space within the valve 27 into the space above the partition 25, compressing the air therein and simultaneously the ram 13 moves upwardly so that the piston 12 further compresses the air in the cylinder 8. The upper end of the cylinder 11 rising into the annular space surrounding the cylinder 8 and the upward movement of the partition 40, increases the air pressure in the space above the partition, and high pressure air passes through the passages 76, 74 into the space beneath the piston 12, and past the valve 73 into the space above the liquid A, if the pressure therein is lower. When compression of the shock-absorber ceases, the compressed air in the space above the partition 66 passes back through the restricted passage 69 while the oil above the partition 25 gradually returns to the cylinder 9, thus slowly restoring the parts to their normal positions. The air pressure in the cylinder 8 is built up by reciprocating the cylinders 10, 11 quickly relatively to each other so that air passes rapidly through the passages 76, 74 past the valve 73 into the space above the oil in the cylinder 8. The cylinder 8 and associated parts form the subject-matter of Specification 637,356. The arrangement of the air cell 37 and valve 36 for the prevention of formation of vacuum in the annular space between the cylinders 10, 11 forms the subjectmatter of Specification 637,360.