Nachi PVD-1B-28P PVD Series Piston Pump | PVD-1B-28P-8AG4 Excavator 303C Replacement

Genlu Hydraulic proudly introduces our PVD Series (comprising PVD-0B, PVD-1B, PVD-2B, and PVD-3B) high-performance, multi-circuit axial piston pumps. This series is engineered specifically to meet the rigorous travel, swing, and digging duty-cycles of modern compact and mini excavators, such as the classic Caterpillar 303C. For the core configuration code PVD-1B-28P-8AG4 (PVD1B28P8AG4), we have thoroughly reinforced the mechanical architecture and optimized the internal fluid dynamics. Serving as the primary hydraulic powerhouse for compact excavators, this pump features a specialized “dual piston pump + single gear pump” integrated monoblock design. Genlu unequivocally guarantees 100% Drop-in Interchangeability in SAE mounting flanges, splined input shafts, plumbing port layouts, and displacement control curves relative to Nachi original equipment. Backed by our uncompromising 100% Simulation Load Testing, each PVD pump is rigorously verified across all high-pressure circuits simultaneously, ensuring synchronized volumetric efficiency and smooth compound movement control with minimized acoustic decibel output.

Technical Specifications 

• Product Series: Nachi PVD Series Main Axial Piston Pump for Compact Excavators

• Core Configuration Model: PVD-1B-28P-8AG4 / PVD1B28P8AG4

• Target Application Machinery: Caterpillar 303C style mini/compact excavator main pump

• Pump Combination Layout: Twin variable displacement piston pumps + Single auxiliary gear pump

• Piston Pump Displacement: 28 cm³/rev × 2

• Rated Operating Pressure: 21 – 24.5 MPa (210 – 245 bar)

• Peak Pressure Rating: 28 MPa (280 bar)

• Control Mechanism: Total constant power regulation (Featuring dual-pump cross-sensing power regulator)

Key Technical Advantages:

• Dual-Pump Flow Merging & Constant Power Control: Equipped with an advanced total power regulator that dynamically throttles pump displacement based on instantaneous system load. During heavy digging or climbing operations, it scales down displacement to prevent engine stalling, while expanding flow during light loads to accelerate cycle times for seamless compound movements.

• Monoblock Space-Saving Housing: Integrates two high-pressure variable piston circuits and one pilot/charge gear pump into a single, compact heavy-duty cast iron body. This design drastically saves precious room within the excavator engine bay and eliminates external loop plumbing, minimizing potential leak paths.

• Bimetallic Cylinder & Valve Plate Interface: The cylinder block-to-valve plate friction pairs utilize a high-strength bimetallic sintered bronze layer bonded onto heavy-gauge steel or ductile iron. This greatly heightens resistance to cavitation erosion and adhesive wear, preserving superior volumetric efficiency under prolonged thermal and high-pressure stress.

• Reinforced Shock-Resistant Bearing Array: Outfitted with heavy-duty, high-capacity ball and roller shaft bearings tailored to withstand external structural vibrations from the engine and intense radial/axial shock loads transmitted through the undercarriage during rough travel.

Application Areas:

• Mini & Compact Excavators: Perfect direct-replacement main hydraulic pump for 3-ton class compact excavators (e.g., Caterpillar 303C, Komatsu, Hitachi, and similar tonnage machinery).

• Compact Drilling Equipment: Main rotary and travel drive circuits for small-scale tracked piling or core drilling rigs.

• Specialty Utility Machinery: Primary fluid supply for specialized skid-steer loaders and compact dredging equipment.

Expert Maintenance Tips:

• Pre-Commissioning Shell Priming: Prior to initial machinery startup or reinstalling after service, the PVD pump housing must be entirely pre-filled with clean system fluid through the upper case fill port. Crank or jog the engine intermittently for a few seconds at low idle to confirm suction and ensure the components never experience dry friction.

• Rigid Filtration Hygiene Control: Compact excavators frequently operate in highly abrasive, dusty open-air jobsites. Regularly service the return line filters and pilot strainer elements. System fluid hygiene must be rigidly maintained within ISO 4406 19/16/13 thresholds to shield precision parts.

• Airtight Intake Line Integrity: Periodically inspect the primary suction hose clamps for looseness or micro-fractures. Any intake air ingestion will immediately trigger severe fluid aeration and violent cavitation, which rapidly leads to pitting damage on the valve plate and catastrophic piston shoe delamination.