GB1344476A - Shock absorbers - Google Patents

Abstract

1344476 Hydropneumatic buffers ALFRED TEVES GmbH 19 April 1971 [4 March 1970] 20166/71 Heading F2S A shock absorber, e.g. for use between a railway vehicle body and a bumper-baulk carrying the buffers and couplers, comprises a cylinder 1 in which a piston 3 normally rests at an end of its path, as shown, and defines one end of a variable chamber 15 from which liquid flow is regulated (e.g. by grooves 13 in a metering rod 4, over which passes the centrallyapertured piston 3, when the latter with its hollow piston-rod 2 enters the cylinder 1), if there is an impact to move the piston into the cylinder 1 from the end position through a shock-absorbing stroke; there is also a valve 10 responsive to the liquid pressure to open a passage 11, 6, 12 for the return of liquid to the chamber 15 (from a chamber 8 in the hollow rod 2) during a first part only of the return stroke of the piston 3 since the passage is ineffective for the latter part of that stroke (when the piston 3 is no longer positioned between cross-bores 9 and 11 in the metering rod 4 and the return stroke is retarded). In the piston-rod 2, a free piston 17 separates the liquid-receiving chamber 8 from a chamber 18 of gas under pressure so that a pressure is maintained in the chambers 8 and 15 and the annular piston 3 is biased to the rest position as shown. Pressure acquired, during a shock-absorbing stroke, by the gas in chamber 18, effects the return stroke. An impact on either end of the shock absorber moves the rod 2 and piston 3 into the cylinder 1 and liquid is displaced from chamber 15 through the parabolically-tapered grooves 13 to open pivoted flaps 14 therein and enter the chamber 8 and an annular space 20, which is enlarged by the movement of the piston 3. There are throttling bores 16 in the grooveclosing flaps 14 for the retarded return flow of liquid into chamber 15. Cross-bores 19 in the wall of rod 2, for communication from the space 20 when enlarged, are normally almost closed, as shown, by a conical surface of the cylinder wall so that the final movement of the piston 3 is gentle.