Electro-hydraulic control valve

Claim 1

AN ELECTRO-HYDRAULIC SERVO VALVE COMPRISING A BODY HAVING AN OPENING THEREIN, PRESSURE FLUID PORTS IN SAID BODY, A MOVABLE MEMBER HAVING SPACED PORTIONS THEREON IN SAID OPENING MOVABLE TO A PLURALITY OF POSITIONS TO CONTROL THE FLOW OF FLUID THROUGH SAID PORTS, MEANS DEFINING A PLURALITY OF FLUID PRESSURE CHAMBERS RESPECTIVELY IN COMMUNICATION WITH SPACED PORTIONS OF SAID MOVABLE MEMBER, MEANS NORMALLY ADAPTED TO CONNECT SAID CHAMBERS SIMULTANEOUSLY TO A SOURCE OF HIGH FLUID PRESSURE AND TO A LOW PRESSURE SOURCE, MOVABLE MEANS POSITIONABLE IN A NEUTRAL POSITION CORRESPONDING TO EQUAL FLUID PRESSURES IN SAID CHAMBERS AND ALSO POSITIONABLE IN DISPLACED POSITIONS TO EFFECT NONEQUAL FLUID PRESSURES IN RESPECTIVE CHAMBERS AND EFFECT THEREBY MOVEMENT OF SAID MOVABLE MEMBER, ELECTRICALLY RESPONSIVE MEANS OPERATIVE TO EFFECT MOVEMENT OF SAID MOVABLE MEANS, AND MECHANICAL MEANS OPERABLE UPON MOVEMENT OF SAID MOVABLE MEMBER EFFECTIVE TO BIAS SAID MOVABLE MEANS TO SAID NEUTRAL POSITION THEREOF.