D634-398C is a pilotless direct drive servo valve belonging to MOOG D634 series with ISO4401-05 (NG10) mounting standard. As the maximum-flow flagship model, it integrates 24VDC drive unit and built-in LVDT spool position closed-loop feedback. Designed for extreme heavy-duty closed-loop hydraulic systems with 350bar high pressure, ultra-large flow and high dynamic response.

Brand: MOOGModel: D634-398CCategory: Pilotless electro-hydraulic direct drive servo valveMounting Standard: ISO4401-05 (NG10)Drive Mode: Permanent magnet linear force motor, no pilot oil requiredPower Supply: 24VDC integrated PWM drive, operating range 18-32VDCFeedback Type: Built-in LVDT closed-loop position detectionReset Mode: Spring centering, auto return to neutral position after power lossProtection Class: IP65Weight: Approx. 11.2kgAlias: High-flow direct drive servo valve, high-pressure DDV servo valve

Core Function: Precisely control hydraulic flow and flow direction via analog control signals. Realize closed-loop regulation of position, velocity, pressure and thrust. It features low pollution sensitivity and pressure-independent dynamic performance.Product Positioning: Top-end high-flow high-response model of D634 series. It replaces multi-stage combined valve sets, perfectly applied to extreme heavy-duty working conditions with high pressure, ultra-large flow and rapid dynamic action.

Max working pressure: 350barMax T-port pressure: ≤50bar (without Y port), ≤350bar (with Y port)Rated flow @35bar pressure drop: 480-500L/minPeak flow: Approx. 630L/minNull internal leakage: ≤9.0L/minApplicable fluid: ISO11158 standard mineral oilFluid temperature: -20℃ ~ 80℃Fluid cleanliness: ISO4406 17/14/11

Full stroke step response: ≤10ms-3dB frequency bandwidth: 95-105HzHysteresis: ＜0.16% full scaleControl resolution: ＜0.06% full scaleTemperature drift: ＜0.8% full scale

Max operating current: 6.0AStandard control signal: ±10VDCOptional signal: ±10mA, 4-20mASpool position feedback: 0-10VDCConnector: M18 6-pin with PE terminalAmbient temperature: -20℃ ~ 60℃Certification: CE compliant

Shielded twisted signal cable, M18 waterproof connectorISO4401-05 standard valve mounting baseHigh-precision hydraulic filter24VDC low-ripple stabilized power supplyServo controller, displacement and pressure sensors

Heavy forging, extrusion and high-pressure hydraulic machineryLarge-scale aerospace and automotive structural test benchesHigh-load vibration test and motion simulation equipmentMarine and offshore engineering hydraulic systemsHigh-end hydraulic control systems for wind power and large construction machinery