GB648932A - Improvements in or relating to fluid-damped shock absorbers - Google Patents

Abstract

648,932. Oleo pneumatic shock absorbers. BRITISH MESSIER, Ltd. April 13, 1948, No. 10254. [Class 108(iii)] In a shock absorber of the fluid-damped type, a restriction valve is provided having a movable valve member held towards a seating by a spring and having also a piston behind the valve member which piston works in and obturates a bore which forms a passage for fluid passed by the valve, a restricted orifice or orifices being provided for the passage of the fluid from the fluid space afforded in the bore between the valve seat and the piston, to a fluid chamber beyond the piston, so that the fluid after passing the valve has further to pass the orifices. In the arrangement shown, in which a piston 12 and a counter-piston 13 are connected by a grooved piston rod 14 and are slidable on opposite sides of a fixed diaphragm 15 within a cylinder 11, a bore 19 in the diaphragm houses a spring loaded piston 18 provided with orifices 21 and carrying a valve member 17, which latter normally seats on a small orifice 16. The diaphragm is also provided with a recoil orifice 23 and flap valve 24. During compression of the shock absorber low rates of fluid flow through the bore 19 are restricted by the valve 17 which lifts only slightly, while for increasingly higher rates of flow, the restriction is first decreased, due to the valve 17 being fully opened, and is then increased when the restriction is due wholly to the orifices 21. In a modification, (Fig. 3, not shown), the orifices through the valve piston are replaced by a restriction orifice through the wall of the bore and communicating with a bore extending through the diaphragm into the fluid space above it.