Servo Valves and Proportional Valves for Industrial Machines

A Hydraulic Servo Valves is a device that meters the flow of oil in response to an electrical input signal or command  to control position, velocity, pressure or force in some type of machine or device (usually through a piston or cylinder). Servo Valves are closed-loop control devices that can be single stage, two-stage or three stage designs.

Moog is a leader in designing, manufacturing, and selling high performance hydraulic valve products. With over 60 years experience producing servo and proportional valves for the industrial market, our products are legendary for reliability and accuracy.  Moog valves contain either a mechanical or electrical feedback mechanism.

Designed and built to meet the unique needs of even the most demanding customers, we offer numerous models with a range of sizes, performance characteristics and mounting options. 

Flow Control Valves

Flow control servo valves are designed to produce hydraulic flow output proportional to electrical current input.  Available valve types include:

  • Integrated digital electronics with optional fieldbus interface
  • Analog interface with integrated electronics
  • Analog interface without integrated electronics


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Pressure and Flow (p/Q) Control

p/Q valves control flow and regulate pressure (upper or lower limiting pressure) and can be used for both pressure regulation as well as applying a pressure-limit.

Our p/Q valves contain integrated digital electronics with optional fieldbus interface.

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Servo Valves and Proportional Valves with Special Features

Offerings include servo valves and proportional valves with advanced safety features such as fail-safe and explosion-proof options (e.g. ATEX certification) as well as special performance modifications including customized spool null cuts.

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Servo Valves and Proportional Valves Accessories

As part of our approach to providing motion control solutions, Moog provides a wide variety of accessories our customers may need for hydraulic valves. From valve checkers for troubleshooting to mounting manifolds for easy installation on machines to configuration software, Moog’s expertise involves helping you to get running quickly and easily.

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What are the components of a servovalve?

  • The pilot stage takes the input or command signal from the controller and provides the hydraulic or mechanical force needed to move the spool of the main stage.
  • The feedback mechanism communicates actual main stage spool position to the pilot stage either by mechanical feedback (MFB) or electrical feedback (EFB).
  • The main stage spool meters hydraulic flow as a function of input signal and provides either mechanical or electrical feedback to the pilot stage. The main stage consists of the valve body and a bushing spool assembly or body spool assembly.  A bushing spool assembly is used in servovalves where a critical lap is required.