Servo-control valve

A hydraulic servo-control valve comprising:

• a polarized electromagnet adapted for connection to an electric current source and having a movable shaft with a first plunger member on one end thereof and a second plunger member on the second end thereof and responsive to electric current of one polarity from the source for urging said shaft, said first plunger member and said second plunger member to move in a first direction and to electric current of opposite polarity for urging said shaft, said first plunger member and said second plunger member to move in the opposite direction;
• a slide member with a third plunger member on one end thereof and a fourth plunger member on the second end thereof, said first plunger member and said fourth plunger member being of different cross-sections;
• and
• means defining a housing having:
• (a) a first chamber with said first plunger member therein;
• (b) a second chamber with said second and third plunger members therein and in contact with each other;
• (c) a third chamber with said fourth plunger member therein;
• (d) said slide member aligned with said movable shaft;
• (e) spring means acting to oppose movement of said shaft and said slide members in the direction of the smaller cross-section plunger;
• (f) an inlet adapted for connection to a source of hydraulic fluid;
• (g) an outlet adapted for connection to a utilizer of pressurized hydraulic fluid;
• and
• (h) a plurality of conduits interconnecting said chambers, said inlet, and said outlet, for flow of hydraulic fluid therebetween, and subjecting said outlet to the hydraulic fluid pressure of said first and third chambers while substantially isolating said second chamber therefrom.