Model Code Definition

D664 = NG25 ISO4401 installation footprint, ServoJet jet-pipe pilot configuration, built-in amplifier + full-travel LVDT spool closed-loop feedback, large-flow D660 subdivision

4784 = Factory preset zero-overlap four-way spring-centered metering spool with tailor-calibrated flow gain, null point fully pre-adjusted at MOOG factory, standard amplifier circuit without special K-parameter custom modification

Technical Specifications

Hydraulic Parameters

Rated Flow:530 L/min @35bar single-side differential pressure; peak instantaneous flow 1752 L/min @70bar supply differential pressure

Max Working Pressure:P/A/B main control ports up to 350bar; built-in T drain ≤210bar; external Y drain withstands full 350bar working pressure

100% Full Stroke Step Response:≤29.2ms under nominal 210bar supply hydraulic pressure

Control Precision:Hysteresis＜0.20%FS, Resolution＜0.060%FS, total thermal drift(-20~+80℃)＜1.90%FS after factory gain fine calibration

Null Leakage:0.22~1.70 L/min determined by original spool machining tolerance

Working Medium:Anti-wear mineral hydraulic oil, fluid cleanliness NAS6~7 / ISO4406 17/14/11, operating fluid temperature -20℃~+80℃

Net Weight:5.83kg

Electrical Parameters

Input Power Supply:24VDC wide voltage range(18~32VDC), static standby current ≤850mA

Default Control Signal:Factory standard ±10VDC differential analog input; ±10mA /4~20mA current signal available via factory custom modification

Connector:11-pin circular aviation socket, IP65 protection after complete cable assembly

EMC Standard:Complies with EN55011 industrial electromagnetic compatibility regulationMoog Inc.

Port & Connection Configuration

Hydraulic Interface:ISO4401 NG25 standard hole layout including P supply port, A/B actuator control ports, separated built-in T internal drain and dedicated Y external drain; pre-installed original NBR mounting gasket, unused X pilot port blocked with factory blank plug for non-external pilot oil application

Electrical Interface:11-pin circular receptacle integrates 24V power supply, ±10V command signal and full-travel LVDT feedback wiring; double-shielded control cable required with single-point cabinet grounding, no fieldbus communication function

Core Functions

1.Patented ServoJet jet-pipe pilot delivers better contamination resistance than conventional nozzle-flapper pilot, ensuring continuous stable running under medium-impurity hydraulic oil in metallurgical production workshops and test laboratories.

2.Optimized fixed flow gain of 4784 spool meets high-precision large-flow closed-loop control requirement; four-way zero-lap spool realizes accurate position/speed/force closed-loop regulation for hot/cold rolling mill and heavy forging hydraulic cylinder; onboard LVDT automatically offsets spool drift induced by ambient temperature fluctuation.

3.Spring-centered fail-safe neutral design: main spool automatically returns to middle position upon power failure to cut off A/B oil path and lock hydraulic actuator, preventing unexpected equipment runaway damage.

4.Factory pre-calibrated built-in amplifier features outstanding anti-interference performance, adapting long-distance analog wiring under harsh industrial field environment.

Typical Application

Hot & cold continuous rolling mill AGC roll gap closed-loop servo adjustment, heavy slab hydraulic forging press master cylinder precise flow control, full-size hydraulic component fatigue test bench, large aluminum/steel extrusion forming equipment, marine hydraulic servo test system.

Installation & Maintenance Instructions

1.Install 3μm high-precision inline high-pressure filter on upstream P supply pipeline; replace filter cartridge after the first 15 working days of equipment commissioning startup.

2.Arrange power cable and shielded control wire inside independent wiring troughs to avoid inverter harmonic interference on analog control signal; fix valve with factory specified bolt torque and standard flat washers.

3.Flow gain and null offset parameters of standard 4784 version are fully preset at MOOG factory; only slight on-site potentiometer fine adjustment is allowed; complete disassembly of ServoJet pilot assembly and main spool component is strictly forbidden.

4.Seal idle spare T/Y drain ports with original factory blank plugs during spare part storage; store valve in dry dustproof warehouse to prevent NBR rubber seal ageing and subsequent oil leakage.