D663-5002 D663-5304K
D663Z4305K D663Z4307K
D663Z4322K D664-4009
D664-4013 D664-4311K
D664-4383K D664-4384K American MOOG German made pressure flow control servo valve

FAQ;

Frequently Asked Questions (FAQ): Moog Electrohydraulic Servo Valves

1. What is an Electrohydraulic Servo Valve?

An electrohydraulic servo valve is a precision component that acts as an interface between the electrical control system and the hydraulic power system. It receives a low-power electrical analog signal and converts it into a proportional, high-power hydraulic output (flow and pressure). This makes it a crucial control core in electrohydraulic servo systems, responsible for both electrical-to-hydraulic signal conversion and power amplification .

2. How does a Moog Servo Valve work?

A Moog servo valve typically consists of a polarized electrical torque motor and a two-stage hydraulic amplifier .

• First Stage: The torque motor deflects an armature and a flapper attached to it. This flapper moves between two nozzles, creating variable orifices that control the pressure on either end of the second-stage spool .

• Second Stage: The differential pressure moves the spool, which then controls the flow of hydraulic fluid to the actuator. A feedback spring, connected to the flapper and engaging the spool, creates a force that balances the input signal torque, ensuring precise spool positioning proportional to the electrical command .

3. What are the key installation requirements?

Proper installation is critical for performance and longevity.

• Filtration: Install a precision filter with a rating of 5 microns or less upstream of the servo valve. The hydraulic fluid cleanliness should be maintained at a maximum ISO DIS 4406 Code 16/13, with Code 14/11 recommended .

• System Flushing: Before installing the servo valve, the entire hydraulic system must be thoroughly flushed to remove contaminants. Use a flushing manifold and circulate fluid under conditions simulating normal operation .