MOOG D633-357B Direct Drive DDV Servo Valve

I. Basic Information
Brand: MOOG (a leading American company in high-precision electro-hydraulic servo valves)
Category: D633 series, ISO03 specification direct-acting DDV servo valve (built-in closed-loop electronics, permanent magnet linear force motor direct drive, no pilot oil)
Model code interpretation: D633-357B
D633: ISO4401 Size03 direct-drive servo valve series
357: Hardware configuration code
Rated flow: 40 L/min (single-sided pressure difference 35 bar)
Analog control signal: ±10V voltage command
Standard 4-way centering spring alignment, built-in LVDT valve core position feedback
Standard 6-way + PE circular aviation connector
B: Standard industrial general version (no explosion-proof, no special failure protection customization)

Core Hydraulic Parameters
Rated flow: 40 L/min @ ΔP=35bar / throttling side; maximum flow limit 75 L/min
Pressure rating
P/A/B working pressure: maximum 350 bar (5000 psi)
Return oil T without external leakage Y port: ≤50 bar; with Y external leakage port can withstand 350bar return pressure
Step response: valve core stroke from 0 to 100% ≤12 ms, high frequency response, dynamic not affected by system pressure
Centering function: spring automatic centering, power-off valve core returns to center position, actuator locked and stops (safety failure design)
Hydraulic medium: ordinary anti-wear hydraulic oil; recommended cleanliness ISO4406 18/15/12; viscosity 15~45 cSt; oil temperature -20~+80℃

Electrical Specifications (Built-in Integrated Drive Board)
Power supply: 24VDC (allowable 18~32VDC wide voltage), low static power consumption, dynamic peak 0.3A
Control command: standard ±10V analog voltage input
Feedback output: LVDT valve core position closed-loop feedback signal, can be externally connected for actual valve core opening degree collection
Drive architecture: built-in PWM power drive + valve core closed-loop control circuit, IP65 protection (with original plug)
Interface: standard 6-pin + grounding aviation connector
Performance indicators
Resolution <0.1%
Hysteresis <0.2%
Temperature drift (55℃ temperature difference) <1% FS
Anti-vibration: three-axis 30g industrial reinforcement standard

Structure and Installation
Installation standard: ISO 4401-03 (NG03, small-size stacked valve installation surface)
Drive principle: permanent magnet linear force motor directly drives the valve core, no pilot oil source required, simplifies hydraulic station and reduces pollution risk
Built-in components: LVDT displacement sensor, PWM drive circuit board, bidirectional centering spring
Installation torque: installation screws diagonally locked 6.8 Nm