GB1049107A - Improvements in hydro-pneumatic suspension systems - Google Patents

Abstract

1,049,107. Adjusting vehicle body height. DAMIC CONTROLS Ltd. Sept. 8, 1965 [June 16, 1964], No. 24930/64. Heading B7D. In a levelling valve for a vehicle suspension, inlet and exhaust ports 5, 4 connected to an engine-driven hydraulic pump P and a reservoir T are communicable with an outlet 8 connected to one or more hydro-pneumatic springs 9 through spring-closed valves 11 which are opened by servo piston 16 controlled by pilot valves 22 when a change in vehicle loading demands fluid flow to or from the springs. Cams C, C<SP>1</SP> actuated by a torsion bar TB sensitive to vehicle body height normally hold the pilot valves 22 open so that fluid supplied to bores 17 above the pistons 16 through a passage (not shown) communicating with the inlet port 5 passes into a passage 26 communicating with the exhaust port 4 by way of a passage 27 (not shown). When the body height changes the cams C, C<SP>1</SP> are displaced by the torsion bar TB and one pilot valve 22 is closed by a spring 23 so that increasing pressure in the bore 17 displaces the piston 16 to open the associated valve 11. Flow restrictors in the passage 31 delay actuation of the pistons 16 to prevent opening of the valves 11 when travelling over uneven ground. A non-return valve 13 in the inlet port 5 retains fluid pressure in the system when the pump P is inoperative. Separate levelling valves may be employed at the front and rear of a vehicle.