05584224 is referenced by 6 patents and cites 7 patents.

An hydraulic lift system has an actuator connected to an hydraulic circuit, having a pump, via a supply line. A balanced seated valve is connected between the supply line and a reservoir, the valve being controlled by a solenoid and an electric drive unit. The drive unit supplies a gradually increasing or decreasing voltage to the solenoid to open or close the valve gradually. The valve has a valve member that is displaceable along its length and has a valve head of frusto-conical shape. A passage along the valve member balances fluid pressure across the valve member. The solenoid has an armature with a pole face that can be displaced towards a fixed pole face to unseat the valve member. The pole faces have complementary frusto-conical surfaces and there is a non-magnetic washer between them.

Title
Hydraulic systems
Application Number
8/541091
Publication Number
5584224
Application Date
October 11, 1995
Publication Date
December 17, 1996
Inventor
Michael J Wallace
Brize Norton
GB
Stephen J Downward
Cheltenham
GB
Anthony R Davies
Cirencester
GB
Agent
Pollock Vande Sande & Priddy
Assignee
Smiths Industries Public Company
GB
IPC
F15B 13/16
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