VDC-1A VDC-1B Variable Vane Pump | Nachi VDC Series Replacement

Genlu Hydraulic proudly introduces our VDC Series (VDC-1A / VDC-1B) industrial-grade, high-efficiency small axial single-vane variable displacement hydraulic pumps. Specifically engineered for close-tolerance industrial applications—including high-precision CNC lathe chucking networks, shoe-making machinery, industrial woodworking equipment, and localized low-pressure automation aggregates—this pump family excels where thermal heat reduction and auto-regulating “high-flow rapid approach to high-pressure holding” control are paramount. This series delivers a precision-manufactured, drop-in replacement for global classic Nachi VDC / VDN / VDR / VDS and matching Toyooki variable volume vane architectures. We specialize in cross-referencing and supplying heavy-duty build specifications, prominently covering the VDC-1A-1A2-20 and VDC-1B-1A2-20 single configurations alongside configured tandem-unit pump packages.

Within high-performance automated circuits, conventional fixed gear or vane pumps waste extensive electrical energy by bypassing full-volume oil across relief valves during clamping and idle phases, triggering severe thermal degradation. Genlu’s VDC series incorporates a highly sensitive, internal spring-loaded pressure compensation mechanism. Once circuit pressure matches the pre-set threshold, the pump automatically adjusts its internal cam ring stroke close to center-zero, slicing active delivery flow and cutting standby power usage to a minimum. Conforming strictly to standard imperial/metric envelopes, we guarantee 100% Drop-in Interchangeability across international SAE standard pilot flanges, standard cylindrical parallel keyed drive shafts, and universal port layouts. Prior to facility clearance, each variable vane unit undergoes 100% deadhead cutoff transient response timing, pressure-tracking resolution auditing, and case-drain slippage checks, ensuring quiet running and minimal power draw under extended holding duties.

Technical Specifications 

• Product Line: VDC Series Small High-Efficiency Variable Displacement Pressure Compensated Vane Pump

• Core Covered Model Formats:

  • VDC-1A-1A2-20 (Size 1A frame, high-pressure execution, pressure range A2 code, design sequence 20)

  • VDC-1B-1A2-20 (Size 1B frame, extended-flow execution, pressure range A2 code, design sequence 20)

• Maximum Geometric Delivery Displacement Matrix:

  • VDC-1A Footprint: 8.0 $cc/rev$ (Yielding approx. 14.4 $L/min$ peak flow @ 1800 rpm)

  • VDC-1B Footprint: 12.0 $cc/rev$ (Yielding approx. 21.6 $L/min$ peak flow @ 1800 rpm)

• Calibrated Pressure Adjusting Threshold Ranges:

  • Stage A1 Envelope: 0.8 MPa to 3.5 MPa (8 bar to 35 bar / 116 psi to 507 psi)

  • Stage A2 Envelope: 3.0 MPa to 7.0 MPa (30 bar to 70 bar / 435 psi to 1015 psi; Primary industrial clamping specification)

• Maximum Permissible Continuous Rated Operating Pressure: 7.0 MPa (70 bar / 1015 psi)

• Allowable Driven Shaft Velocity Boundaries: Minimum speed 800 rpm; Maximum rated speed 1800 rpm

• Primary Regulation Form: Direct-acting dynamic spring-opposed pressure compensation control

• Drive Shaft Specification Profile: Standard cylindrical straight parallel keyed layout (ideal for coupling directly to standard IEC/NEMA electric motors)

Key Technical Advantages:

• Precise Cam Ring Lateral Shifting for Low Deadhead Power Loss: The core internal cam ring is built on a responsive, lateral sliding carrier backed by a calibrated high-flex control spring and feedback piston. As system pressure nears the A2 setting, fluid forces push the ring toward center alignment. At full deadhead pressure, eccentric displacement drops close to zero, keeping delivery flow just high enough to offset internal lubrication leakage and slashing power draw by over 80%.

• Premium Wear-Resistant Alloy Port Plates for High Volumetric Efficiency: The matching side port plates are cast from high-density, anti-friction copper alloy and fine-ground to nanometer specs. This choice establishes a reliable hydrodynamic fluid film between the rotating vane tips and the inner cam track, lowering friction and maintaining excellent volumetric efficiency under continuous 7.0 MPa pressure.

• Integrated Acoustic Dampening Slots for Ultra-Quiet Operation: To counter the localized pressure spikes typical of variable displacement transitions, the pump body incorporates a dedicated fluid dampening chamber paired with variable-curvature V-grooves on the timing lands. This arrangement smooths out pressure ripples during shifting, keeping noise levels between 55-60 dB for quiet workshop operation.

• Compact Lightweight Engineering with Thru-Shaft Tandem Capability: The VDC-1A/1B housings are cast from high-strength, lightweight die-casting alloys, creating an exceptionally compact profile with a small footprint. Additionally, the through-shaft architecture allows engineers to tandem-mount a secondary VDC pump or a high-pressure gear unit on a single motor drive, simplifying dual-pressure circuit layouts.

Application Areas:

• High Precision CNC Lathe & Machining Center Chucking Circuits: Continuous, un-interrupted high-pressure holding for spindle power chucking, tailstock cylinder positioning, and automatic tool-changer locks.

• Industrial Shoe-Making & Lightweight Leather Processing Machinery: Rapid tool approach and high-load pressure clamping sequences for automated industrial lasting, cutting, and leather embossing presses.

• Automated Multi-Station Transfer Lines & Specialized Workholding Sub-Stations: High-cycle cylinder positioning and positive work-holding locks for automotive welding fixtures and precision assembly arrays.

Expert Maintenance Tips:

• Pre-Fill the Pump Casing and Case Drain Manifold Before Initial Startup: The internal sliding cam tracks and vane guide channels rely heavily on immediate fluid lubrication at startup. Before starting the motor, fill the pump case with clean hydraulic oil through the top case drain port. Ensure the drain line routes directly back to the reservoir without restriction and terminates below the minimum oil level to prevent air from entering the system. Running dry for even 10 seconds will cause rapid friction wear and score the internal cam tracks.

• Loosen the Pressure Adjustment Screw Completely During First Commissioning: When firing up a newly installed unit, turn the top pressure adjustment screw counter-clockwise until it is fully loose. Start the electric motor and let the pump idle under zero load for 5-10 minutes to safely purge air from the internal chambers. Once the loop runs smoothly, watch the inline pressure gauge while slowly turning the adjustment screw clockwise to dial in your target holding pressure.

• Enforce Tight Controls on Fluid Viscosity and Operating Temperatures: Variable vane pumps depend on stable oil characteristics, making them highly sensitive to viscosity changes. We recommend using premium anti-wear hydraulic oil rated at ISO VG 32 or 46, keeping working temperatures strictly between 15°C and 60°C. Excessive heat thins the fluid and increases internal leakage, which can disrupt the pressure feedback loop and cause system pressure to oscillate erratically.