GB641527A - Improvements in telescopic shock-absorbers for resisting loads operating in tension - Google Patents

Abstract

641,527. Liquid-spring shock-absorbers. DOWTY EQUIPMENT, Ltd., and BINGHAM, A. E. June 16, 1948, No. 16231. [Class 108(iii)] A shock absorber of the kind in which resilient compression of entrapped liquid affords resistance to loads operating in tension, and expansion of the liquid is controlled by damping orifices, comprises two chambers arranged concentrically in overlapping relation, one chamber being essentially of greater volume than the other, the smaller chamber being constituted by the annular space around a piston rod extending into a cylinder at one end and carrying a piston slidable in the cylinder, the cylinder being open to atmosphere at the other end, there being one or more restrictions affording the sole communication between the two chambers, and liquid filling the larger chamber and the maximum available space in the smaller chamber. In the construction shown in Fig. 1, the larger chamber 11 is formed by an outer cylinder 12 surroundthe cylinder 13 defining the smaller chamber 10. Communication between the two chambers is by way of one or a few restricted orifices 22 and by several orifices 23. Flow through the orifices 22 is controlled by a rigid ring 24 having an annular channel 24A and a plurality of communicating ports 24B, 24C. Flow through the orifices 23 is controlled by a resilient split-ring 25 which prevents flow into the smaller chamber but permits it in the reverse direction. The end 19 of the cylinder 13 is reduced in thickness and seats on a packing ring 18 in an annular recess in the end of the outer cylinder 12. Thus liquid pressure acting on the cylinder 13 in the orifices 22, 23 produces slight axial movement of the cylinder 13 to compress the packing 18 to a greater pressure than that of the liquid. Packing gland means 15, 17 for the piston rod and piston respectively is of the unsupported area type described in Specification 539,966, [Group XXVI]. In the construction shown in Fig. 2 the larger chamber 11A is constituted by a hollow space in the piston rod 26. Fixed flow restriction means 27 are provided between the two chambers.