Hyundai HL770-7A HL770-9S Hydraulic Main Pump | 31LB-00400 707565

The 31LB-00400 Hydraulic Piston Pump from LIC Hydraulic is the high-performance heart of the Hyundai HL770-7A and HL770-9S wheel loader series. Also cross-referenced as Part No. 707565, this tandem variable displacement pump is engineered to deliver precise flow control for heavy-duty digging, lifting, and steering operations. Built to meet or exceed OEM specifications, this pump ensures that your Hyundai fleet maintains factory-level cycle times and fuel efficiency. We provide 100% drop-in replacements, matching original mounting interfaces and spline configurations perfectly.

Technical Highlights

• Part Numbers: 31LB-00400, 31LB00400, 707565.

• Application: Hyundai HL770-7A / HL770-9S Wheel Loaders.

• Design: Tandem Axial Piston Pump with integrated regulators.

• Max Pressure: Rated for high-pressure industrial environments up to $350\text{ bar}$ ($5075\text{ psi}$).

Core Advantages

• Dynamic Load Response: The integrated regulator system is fine-tuned to react instantly to operator commands, delivering the exact power required for the task while minimizing hydraulic heat buildup and energy waste.

• Rugged Construction: Featuring high-tensile cast-iron housings and hardened steel rotating groups, the 31LB-00400 is built to withstand the shock loads and abrasive dust common in construction and mining sites.

• Enhanced Volumetric Efficiency: Precision-lapped valve plates and piston shoes minimize internal oil bypass, ensuring maximum power delivery to the cylinders and motors even at high operating temperatures.

• Simplified MRO (Maintenance, Repair, and Operations): Designed as a direct bolt-on unit, it requires no modifications to the existing Hyundai engine housing or hydraulic line layout, significantly reducing machine downtime.

Expert Maintenance Tips

• Hydraulic System Purge: When installing a new 31LB-00400, it is mandatory to flush the hydraulic reservoir and lines. Any debris from a catastrophic failure of the previous pump will score the new precision-ground parts.

• Prime the Case: Before engine start-up, fill the pump case with clean hydraulic fluid through the top drain port. Running a tandem pump “dry” will cause permanent internal damage within seconds.

• Filtration Integrity: Always replace the main return and suction filters with high-quality 10-micron elements. Maintaining ISO 18/16/13 oil cleanliness is the single most important factor for the longevity of this high-pressure unit.

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