Description
MOOG D691-072D
Technical Specifications Mounting pattern conforms to ISO 4401; maximum working pressure reaches 315 bar; rated flow is determined by pressure drop across valve ports; command signal accepts ±10 V analogue voltage; built-in LVDT spool position feedback sensor; operating hydraulic fluid temperature covers -20 ℃ to +80 ℃; ambient operating temperature ranges -20 ℃ to +60 ℃; recommended fluid cleanliness level meets ISO 4406 18/15/12; electrical connector with IP65 protection when fully mated; hysteresis less than 0.5 %; resolution less than 0.1 %.
Functional Features Direct drive structure eliminates pilot stage leakage; integrated LVDT provides real-time spool position closed-loop feedback; embedded electronic amplifier supports gain and zero point calibration; pQ control mode switches between pressure regulation and flow regulation according to system demand; internal self-diagnosis detects signal loss, spool fault and over-temperature conditions; spring centering returns spool to neutral position when power supply fails.
Application Scenarios Metal stamping presses, hydraulic bending machines, injection moulding machine clamping control, material fatigue test rigs, steel rolling mill hydraulic cylinder control.
Material Composition Valve body uses high-strength alloy steel with precision honed flow ports; spool and sleeve adopt hardened alloy material with ultra-low clearance; electronic housing is made of aluminium alloy with anti-corrosion surface treatment; sealing elements use fluorocarbon elastomer compatible with mineral hydraulic oil; internal PCB is FR4 multilayer circuit board with conformal coating.
Structural Characteristics Monoblock valve body with standard ISO flange installation; hydraulic oil ports arranged on bottom mounting surface; electronic drive unit and LVDT feedback sensor assemble on upper valve body; side-mounted circular electrical connector separates power supply and command signal pins; internal flow channels optimise flow distribution and reduce turbulence loss.
Working Principle Analogue ±10 V command signal transmits to onboard electronic amplifier. The amplifier drives the direct drive torque mechanism to displace the main spool. LVDT sensor measures actual spool position and feeds value back to control circuit. Control circuit continuously adjusts drive output to minimise deviation between command position and measured spool position. Spool displacement modulates opening area of hydraulic ports to control flow rate and pressure delivered to hydraulic actuator.
Installation Requirements Mount valve on rigid, flat hydraulic manifold block; torque mounting bolts to manufacturer specified torque value; install high-pressure filter upstream of valve to maintain required fluid cleanliness; use shielded twisted pair cable for analogue command signal; separate signal wiring from high-current power cables; bleed air from hydraulic circuit before commissioning.
Operation Notes Flush entire hydraulic pipeline to remove particulate contamination before valve startup; do not apply electrical command signal without pressurised hydraulic supply; execute zero and gain adjustment after installation or maintenance; inspect sealing rings and connector pins during scheduled overhaul.
