GB1500714A - Shock absorbers - Google Patents

Abstract

1500714 Hydropneumatic shock absorbers with varying spring rate OLEO INTERNATIONAL HOLDINGS Ltd 5 May 1975 [8 May 1974] 20234/74 Heading F2S In a hydropneumatic shock absorber (Figs. 1A and 1B, not shown), the gas and liquid are separated by a movable wall 24A, 24B; liquid displaced through throttling means (including the orifice in wall 14A, 14B) on compression of the shock absorber acts to displace the movable wall and compress the gas; the gas space comprises two chambers 26, 27, the gas in the chamber 26A, 26B acting at all times on the movable wall; and a spring-biased valve 56, 62 prevents communication between the gas chambers until opened automatically when the shock absorber has been compressed to a certain length. On extension the valve recloses when this length is again reached. The gas in the chamber 27 is required to be at a higher pressure than that in the chamber 26. The shock absorber is a railway vehicle buffer and comprises a plunger 10A, 10B bearing an impact head (Fig. 1) at its L.H. end, and sliding in a liquid containing cylinder (11, Fig. 1). On impact, the plunger enters the cylinder and liquid is displaced into the chamber 25A, 25B through the orifice controlled by a metering pin (16, Fig. 1) fixed to the cylinder base, and a flexible annular valve member (23). The liquid displaces the movable wall which is a floating piston 24A, 24B, and this displacement causes a pin 58, 64 on the piston (Fig. 4) or the plunger (Fig. 6) to open the valve, so that further compression of the shock absorber compresses the gas in both chambers. In Fig. 1, the chambers are separated by a movable partition (28) and a stem (32) projects from the L.H. end wall of the plunger and carries a valve head which seats on the partition.