Rexroth A4VG A4VTG Charge Pump | A4VG125 A4VG250 A4VG90 | Hydraulic Filling Pump

The A4VG and A4VTG Series Charge Pumps from LIC Hydraulic are essential precision components for Bosch Rexroth closed-circuit variable displacement pumps. These filling gear pumps (including A4VG125, A4VG250, and A4VG90) are responsible for maintaining the low-pressure loop, providing cooling oil flow, and supplying the pilot pressure required for the swashplate control. We provide 100% drop-in replacements, ensuring that your hydraulic system maintains peak performance and prevents catastrophic cavitation of the main pump.

Technical Highlights

• Pump Compatibility: Fits A4VG (Sizes 40-250), A4VTG (Sizes 71, 90), and A10VG/T series.

• Function: Internal/External gear pump for charge pressure and pilot oil.

• Pressure Rating: Designed to sustain continuous charge pressure of $25\text{–}35\text{ bar}$.

• Mounting: Direct drive from the main pump rear shaft.

Core Advantages

• Reliable Priming Performance: Our charge pumps are engineered to deliver immediate oil flow upon engine startup, ensuring the main piston groups are lubricated before the system reaches full load.

• Heavy-Duty Durability: Built with hardened gears and precision-ground side plates to withstand the heat and vibration of heavy construction and mining duty cycles.

• Optimized Pilot Control: Provides a clean, ripple-free oil supply to the hydraulic control valves (HD, HW, DA), resulting in responsive and accurate machine handling.

• OEM Specification Matching: From spline tooth profiles to housing tolerances, every pump is tested to ensure a perfect “bolt-on” installation without modifications.

Expert Maintenance Tips

• Suction Line Sealing: Ensure the suction hose connected to the charge pump is 100% airtight. Any air ingress (aeration) will lead to foam in the closed loop and damage the main pump’s cylinder block.

• Filter Quality: The charge pump is the first component to see oil from the tank. Use high-quality 10-micron filtration to prevent debris from scoring the gear teeth and side plates.

• Pressure Calibration: After installation, always check the charge pressure at the main pump gauge port. If the pressure is too low, the main pump will cavitate; if too high, it may cause shaft seal leaks or excessive parasitic power loss.