Moog Servo Valve Electro-Hydraulic Servo Valve with Up to 350 bar Pressure 25cm Nominal Diameter and 36 Operating Temperature

D634-345C D634-346C
D634-358C D634-361C
D634-362C D634-368C
D634-371C D634-372C
D634-373C D634-374C Hydraulic valve MOOG electro-hydraulic servo valve high pressure control flow pressure

FAQ:

Frequently Asked Questions (FAQ): MOOG Electro-Hydraulic Servo Valves

Product Overview

1. What is a MOOG Electro-Hydraulic Servo Valve and how does it work?

A MOOG Electro-Hydraulic Servo Valve is an electro-hydraulic conversion and power amplification component. Its primary function is to receive analog electrical control signals and then proportionally adjust the output flow and pressure of hydraulic fluid based on these signals, thereby achieving precise control of hydraulic actuators . Essentially, it converts tiny electrical signals into high-power hydraulic output, making it a core component in electro-hydraulic servo systems .

Most MOOG servo valves are two-stage valves. In the first stage, an electrical signal is sent to a torque motor, which moves a flapper between two nozzles, creating a pressure differential. This pressure difference acts on a spool (the second stage), moving it to control the main hydraulic flow to the load. The valve may use mechanical feedback (e.g., a spring) or an electrical feedback system (LVDT sensor) to ensure the spool position accurately corresponds to the input command signal .

2. What are the main advantages of MOOG Servo Valves?

MOOG servo valves are known for several key advantages :

• High-Precision Control: They offer exceptional control accuracy, which can reach about 0.1%, suitable for demanding applications.

• High Dynamic Performance: They feature fast response times, often in the millisecond range, allowing for high-speed and high-precision control.

• High Reliability and Stability: Designed with advanced technology and materials for stable long-term operation, even in harsh environments.

• Variety of Designs: Available in various series, including standard two-stage, high-performance two-stage and three-stage, and direct-drive valves (DDV) to meet different performance needs.

• Fail-Safe Functionality: Some models include a fail-safe feature that moves the valve to a safe position in case of a power failure or system fault .

Series and Specifications

3. What are the main series of MOOG Servo Valves?

MOOG offers a comprehensive range of servo valves. Some prominent series include :

• G761 Series: A popular two-stage flow control valve with mechanical feedback. Known for fast response and robustness, it is widely used in various industrial applications .

• D630 Series (e.g., D634, D636, D637): These often feature direct drive by a linear force motor (DDV) or advanced control. The D636/D637 series, for example, comes with a fieldbus interface and integrated digital electronics for high flexibility .

• D660, D661, D662 Series: Classic two-stage servo valves with a wide range of industrial uses .

• 72 Series: Standard response two-stage valves with a field-replaceable pilot valve filter and the option for external pilot pressure control .

The table below summarizes the key features of some common series:

Series Example Key Characteristics Typical Applications / Features
G761-3003B Two-stage, mechanical feedback, high response Industrial machinery (e.g., metal forming presses)
D634-341C Pilot-operated, closed-loop spool control with LVDT Precision control systems
D636/D637 Direct Drive (DDV), linear force motor, fieldbus interface No pilot leakage, high dynamics, programmable
72 Series Standard response, replaceable pilot filter Power generation (steam/gas turbines)

4. What are the typical operating parameters for MOOG Servo Valves?

While specifications vary by model, general operating parameters can include :

• Maximum Operating Pressure: Up to 4000-4500 psi (approx. 31.5 MPa) for many models.

• Flow Control Range: From a few liters/minute (e.g., 3.8 L/min) to very high flows (e.g., 3800 L/min), depending on the valve size and type .

• Input Signal: Typically a current signal (e.g., ±40 mA) or a voltage signal. Modern valves may accept digital fieldbus commands .

• Coil Resistance: Typically, each coil in the torque motor has a specific resistance, for example, in the range of 72-88 Ω .

• Operating Temperature: A common range is -20°C to 80°C .

Applications, Troubleshooting, and Maintenance

Up to 350 bar Moog Servo Valve

25cm Nominal Diameter Electro-Hydraulic Servo Valve

36 Operating Temperature Proportional Flow Control Valve

Moog Servo Valve Electro-Hydraulic Servo Valve with Up to 350 bar Pressure 25cm Nominal Diameter and 36 Operating Temperature Images