KDG4V Proportional Valve KDG4V-3 KDG4V-5 Vickers Eaton Replacement

The industrial-grade Vickers / Eaton Compatible KDG4V Series Direct Operated Proportional Directional Control Valves, engineered by Chengyuan Hydraulic, are premium fluid-power components designed for the continuous, infinitely variable regulation of hydraulic fluid flow rate, direction, and actuator acceleration/deceleration. Serving as the primary technical foundation for precision closed-loop or open-loop electro-hydraulic systems, this line comprises two dominant industrial form factors: KDG4V-3 (Nominal Size 6 mm / NG6 / CETOP 03) and KDG4V-5 (Nominal Size 10 mm / NG10 / CETOP 05).

This high-performance valve portfolio targets the global B2B industrial component aftermarket and machinery manufacturing sectors, delivering 100% direct drop-in interchangeability with classic, high-frequency procurement Vickers reference models, including: KDG4V-5-33C50N-H-MU-HA7-30, KDG4V-3-2C20N-Z-M-U-H7-60, and KDG4V-3-2C28S-M-U-H7-60 (also referenced as KDG4V32C28SMUH760).

Chengyuan’s alternative proportional valve arrays are manufactured in strict compliance with universal international ISO 4401 mounting configuration matrices. Every physical and functional operational boundary—including the subplate interface footprint, bolt-hole grid arrays, electrical coil Pin assignments, and inlet-to-outlet volumetric flow-to-current metering curves—perfectly mirrors native Vickers technical manual criteria. On integrated automated production floors or heavy mobile platforms, field mechanics can execute rapid component change-outs immediately without requiring rewiring of PLC digital/analog output channels or modification of existing proportional card parameters (such as Eurocard electronic drivers).

Because direct-operated proportional spools function under single-micron clearance thresholds without mechanical spool feedback loops, they are susceptible to system oil degradation, high magnetic hysteresis, and dynamic drift induced by continuous pressure waves. To ensure reliable performance under extreme conditions, 100% of Chengyuan’s KDG4V series proportional valves undergo 100% strict dynamic simulation testing on digitized load blocks. Verified at continuous pressures up to 315 bar, every valve is certified for localized flow-drop linearity, symmetrical deadband distribution, and restricted hysteresis ratios to provide long-term operational precision.

Technical Specifications

• Product Classification: Direct Operated Proportional Directional Spool Valve without Electrical Position Feedback

• Compatible Reference Platform Series: Flawless adaptation for Vickers / Eaton KDG4V-3 (60 design series) and KDG4V-5 (30 design series) electro-hydraulic control architectures

• Nominal Sizing Footprint & ISO Compliances:

  • KDG4V-3 Product Line: Size 6 mm (fully compliant with ISO 4401-03-02-0-05 interface standards)

  • KDG4V-5 Product Line: Size 10 mm (fully compliant with ISO 4401-05-04-0-05 interface standards)

• Maximum Permissible Circuit Pressure Ratings (P, A, B Ports): 315 bar (31.5 MPa / 4500 psi)

• Maximum Permissible Return Tank Line Back-Pressure (T Port):

  • KDG4V-3 Series Form Factor: 210 bar (21 MPa)

  • KDG4V-5 Series Form Factor: 160 bar (16 MPa)

• Technical Model Coding Decoupling & Precision Parameters:

  • Replacement Reference: KDG4V-3-2C20N-Z-M-U-H7-60

    • Configuration: Size 6 mm valve; “2C” specifies a 3-position 4-way spring-centered layout with an all-ports-blocked closed neutral center; “20N” indicates a nominal rated flow of 20 L/min at a reference single-valve-land pressure drop of $\Delta p$ = 10 bar; “Z” denotes a linear flow profile; “M” represents manual override pin actuation; “U” marks standard ISO 4400 / DIN 43650 junction connections; “H7” signifies a heavy-duty DC 24V proportional coil block.

  • Replacement Reference: KDG4V-3-2C28S-M-U-H7-60 (KDG4V32C28SMUH760)

    • Configuration: Size 6 mm valve; “2C” closed-center spool layout; “28S” designates an upgraded high-capacity core delivering a rated flow output of 28 L/min at $\Delta p$ = 10 bar per metering land, with maximum transient flow thresholds up to 42 L/min; driven by a DC 24V proportional coil.

  • Replacement Reference: KDG4V-5-33C50N-H-MU-HA7-30

    • Configuration: Size 10 mm valve; “33C” identifies a specialized asymmetric metering spool configured to balance asymmetric volumetric flow on differential cylinders; “50N” signifies a nominal flow rating of 50 L/min at $\Delta p$ = 10 bar per land, with peak volumetric capacities reaching 80 L/min; “HA7” designates an optimized high-thrust proportional solenoid matched to the 30-design block series.

• Electrical Control Requirements: Recommended for operation via constant-current proportional amplifiers incorporating superimposed Dither signals; maximum solenoid drive current limits range from 1.5A to 2.8A depending on configuration sizing.

• Valve Core Hysteresis Limits: <= 8% of maximum spool travel (restricted further to < 4% when utilized with optimized Dither frequency boards)

• Target Fluid Cleanliness Criteria: Must strictly comply with ISO 4406 18/16/14 or better (minimum recommended absolute system filtration rating of 10 microns)

• Component Net Weight: KDG4V-3 dual-solenoid configuration is approx. 2.4 kg; KDG4V-5 dual-solenoid configuration is approx. 4.6 kg.

Key Technical Advantages

• Precision-Ground Spools with CNC-Milled Flow Metering Notches: The internal sliding spools are machined from specialized premium alloy steel, undergoes deep cryogenic quenching to secure a surface hardness exceeding 60 HRC, and finished via CNC cylindrical micro-grinding. Precision electro-discharge and grinding techniques produce refined V-notch or rectangular metering edges, ensuring predictable, highly linear orifice area expansion relative to coil input current for micron-level metering resolution.

• High-Thrust Wet-Pin Pressure-Impervious Proportional Solenoid Tubes: The electromagnetic armatures function fully submerged within the hydraulic system’s internal return fluid (T-line). This configuration eliminates traditional dynamic shaft-seal components, avoiding external oil leaks, while providing an exact linear current-to-force curve. The robust coil casing features a thermal-stabilized coating to withstand high-duty radiant environments.

• Five-Chamber Flow-Balanced Ductile Iron Housing Matrix: The primary subplate body is cast from high-grade ductile iron using an optimized 5-chamber shell manufacturing architecture. This spacious internal fluid gallery layout balances static pressure loads across different spool strokes, minimizing hydrodynamic lateral forces (flow force) to eliminate spool binding during high-velocity flow loops.

• Low Hysteresis and Superior Dynamic Frequency Shifting: The heavy-duty internal centering spring arrays undergo millions of compression cycles to maintain exceptional stiffness uniformity. Combined with low-inductance proportional solenoids, this ensures rapid small-signal dynamic response and precise spool positioning repeatability across both directions.

Application Areas

Chengyuan’s high-performance replacement Vickers KDG4V-3 and KDG4V-5 series proportional directional valves deliver exact fluid modulation across high-load modern production frameworks:

• Modern Plastic Injection Molding & Rubber Extruders: Managing precision multi-stage injection cylinder speed velocity profiles and low-force mold protection travel loops.

• Heavy-Duty Sheet Metal Forming Presses & Hydraulic Shears: Ensuring smooth transitions between high-speed cylinder down-stroke, slow compression pressing, and high-speed return cycles without shock waves.

• Automated Pulp, Paper, & Material Handling Conveyors: Governing proportional synchronized velocity control circuits utilizing high-torque hydraulic motors.

Expert Maintenance Tips

• Prior to Positioning the Proportional Valve on the Manifold, Verify System Fluid Cleanliness Complying with ISO 4406 18/16/14 (NAS Class 7) via Direct Sampling: Proportional spools operate within single-digit micron tolerances. If the hydraulic oil contains unfiltered particulate debris or suspended carbon sludge, these contaminants will instantly lodge within the micro-notches, causing spool seizure, flow output steps, or erratic drift during initial startup.

• Mount the Valve Assemblies Onto Subplate Interfaces strictly with a Calibrated Torque Wrench to Avoid Asymmetric Distortion: Enforce tight fastening limitations—tighten KDG4V-3 mounting bolts (Class 12.9) to precisely 5.5 N·m, and KDG4V-5 mounting bolts to precisely 12.5 N·m. If the manifold surface flatness deviates past 0.01 mm or if the bolts are over-torqued unevenly, the resulting physical stress will warp the precision iron bore, causing elevated spool friction and magnetic hysteresis.

• If the Valve Exhibits Erratic Shifting or an Excessive Operational Deadband at Startup, Verify the Superimposed Dither Settings on the Proportional Card First: Because direct-operated valves function without a position transducer feedback loop, they rely purely on current balancing against spring force. A high-frequency AC Dither signal (typically 100 Hz to 200 Hz) must be adjusted on the driver amplifier. This dither signal keeps the spool in a continuous microscopic vibration state, overcoming static friction and oil film adhesion to minimize hysteresis.