GB1226534A - - Google Patents

Abstract

1,226,534. Damped pneumatic springs. WILMOT-BREEDEN Ltd. 24 June, 1968 [24 June, 1967], No. 29252/67. Heading F2S. A damped pneumatic spring has a main piston 13 with a passage or passages (not shown) through which gas can flow and an ancillary piston 15 with more restricted gas passages 27. Both pistons are fitted in a closed ended cylinder filled with compressed gas, e.g. nitrogen at 120 atmospheres pressure. The ancillary piston 13 is loaded by a spring 16 of such dimensions that over part of the range of travel of the main piston the ancillary piston is ineffective, but that as the main piston approaches one end of the cylinder it engages the ancillary piston and its further movement is damped by the flow restriction produced by the passages 27. The ancillary piston may be mounted as shown at the piston-rod end of the cylinder, or at the other end, or there could be an ancillary piston at each end. The gas passages in the main piston may (Fig. 4, not shown) be axial channels in the piston periphery, or a single through hole may be provided in the piston and such a hole may contain a damping valve. The cylinder is charged with gas: either through the pistonrod end seal 8, which for this purpose would be constructed as a one-way seal; or through a valve at the other end of the cylinder. Such valve may be a ball valve (Fig. 2, not shown) or a displaceable piston-like end seal for the cylinder end (Fig. 8, not shown). Fig. 8 also depicts minor modifications of the piston-rod end seal and of the ancillary piston.