Abstract: The invention is a mechanical-type position-sensing and feedback system employed between a main stage spool valve and a pilot stage spool valve of an electro-hydraulic servovalve. The feedback mechanism makes use of a rotatable feedback link that directly senses the position of the slide of the main stage valve and transforms a linear motion of the slide into a linear movement of the sleeve of the pilot stage valve. The feedback link has an elongated body and is adapted for rotation about its body's longitudinal axis.

Abstract: The invention is a multi-stage electro-hydraulic servovalve having a mechanical feedback between the valve's main and pilot stages. The feedback mechanism makes use of an interconnected set of linkages that transform a linear motion of the main stage slide into a rotative movement of a torque rod that can produce a translation of the pilot stage slide. Many of the linkages of the feedback mechanism are located exterior to the valve's fluid boundary and feature readily adjustable connections through which a user can adjust various parameters of the feedback such as the degree of gain and null point.