مضخة هيدروليكية Nachi PVD-08-18P-6G3-4191A 4654364 لـ حفارة صغيرة Hitachi ZX16-3 ZX17U-2 ZX18-3

1. Product Identification
Component: Main Hydraulic Variable Displacement Axial Piston Pump Assembly

Manufacturer Model Number: Nachi PVD-08-18P-6G3-4191A (PVD Series Architecture)

Hitachi OEM Part Number: 4654364

Machine Compatibility:

Hitachi ZX16-3

Hitachi ZX17U-2

Hitachi ZX18-3 Mini Excavator

Condition: Genuine Original New / Premium OEM Specification Equivalent

2. Technical Specifications
Pump Type: Variable Displacement Axial Piston Pump with Auxiliary Gear Section

Flow & Pressure Control: Factory-engineered displacement thresholds, pressure limits, and flow curves calibrated specifically for Hitachi 1.6 to 1.8-ton mini excavator auxiliary and main implement circuits.

Drive Configuration: Heavy-duty input spline shaft designed to couple directly with the engine flywheel dampener.

Integrated Control Network: Features integrated regulators to balance hydraulic output and prevent engine lugging or stalling during combined multi-function operations.

3. Critical Installation Requirements
Hydraulic Pump Housing Priming (Mandatory)
Before starting the engine, manually pre-fill the main pump casing with clean, fresh hydraulic fluid through its highest case drain port. Running an axial piston pump dry—even for a few seconds—will score the valve plate and piston slippers, causing immediate total pressure loss.

Air Bleeding & Initial Startup Procedure
After installation, loosen the air bleed port on top of the pump housing. Crank the engine with the fuel supply disabled until clear, bubble-free oil flows from the port, then retighten. Allow the machine to idle under no load for 10 to 15 minutes to purge any trapped air from the hydraulic system.

Fluid & System Decontamination
If replacing a pump that suffered internal mechanical breakdown, completely drain and clean the main hydraulic oil reservoir, flush all circuit lines, and clean the oil cooler. Replace all return and suction filter elements before starting the engine.

Pilot & Main Relief Pressure Inspection
Verify system pressure relief valve settings upon startup. Incorrect pressure settings can lead to sluggish hydraulic response, circuit overheating, or engine stalling under heavy digging loads.

4. Frequently Asked Questions (FAQ)
Q: Is the Nachi PVD-08-18P-6G3-4191A a direct replacement for Hitachi part number 4654364?
A: Yes. Nachi is the original hydraulic pump manufacturer for these Hitachi mini excavator models. Part number 4654364 cross-references directly to this Nachi PVD-08 model, matching all physical mounting dimensions, input shaft splines, and hose port locations.

Q: My Hitachi ZX17U-2 bogs down or stalls the engine when lifting heavy loads. Is the main hydraulic pump at fault?
A: Engine stalling under load typically indicates that the pump regulators are failing to destroke properly when pressure spikes, or that internal wear has degraded hydraulic control balance. Installing a replacement pump assembly restores proper engine-to-hydraulic power balance.

Q: Does the unit come complete with the auxiliary gear pump section attached?
A: Yes. The unit comes fully assembled as a single integrated pump assembly, including the main axial piston pump section, factory-adjusted regulator blocks, and the auxiliary gear pump section.

5. Shipping & Logistics
Packaging: Treated with rust-inhibiting anti-corrosion storage oil, sealed with heavy-duty port plugs, and packed inside an export-safe protective crate or box.

Transit Time: Global express air freight via DHL/FedEx/UPS typically delivers within 3 to 7 business days directly to your workshop or job site.