A4VG125 Rexroth Variable Piston Pump 400Bar

Product Overview:

Engineered to meet the severe load demands of closed-circuit hydrostatic drives in mobile machinery and heavy industrial equipment, our A4VG series closed-loop variable displacement axial piston pump offers a world-class OEM replacement solution. This unit is fully interchangeable with the Bosch Rexroth A4VG Series 32, specifically tailored for advanced configurations like the A4VG125EP2D1/32R-NSF02K69XEH-S. As a dedicated manufacturer of high-pressure hydraulic components, our distinct advantage is guaranteed 100% Drop-in Interchangeability. Every A4VG125 pump undergoes rigorous 100% simulated closed-circuit load testing on automated test rigs before shipment. From precise displacement control curves to high-pressure dynamic response, it mirrors the original unit’s performance, drastically reducing your operational downtime and procurement costs without compromising power output.

Technical Specifications

• System & Compatibility: Closed-circuit systems / Compatible with Rexroth A4VG (Series 32)

• Specific Model Code: A4VG125EP2D1/32R-NSF02K69XEH-S

• Max Geometric Displacement: 125 cm³/rev (Variable, over-center design)

• Nominal Operating Pressure: 400 bar (5800 psi)

• Maximum Peak Pressure: 450 bar (6500 psi)

• Max Permissible Speed: 3200 rpm

• Control Type: EP2D1 (Proportional electrical control, 24V DC, with pressure cut-off)

• Direction of Rotation: R (Clockwise, viewed from shaft end)

• Integrated Boost Pump: Standard (for charge and control pressure supply)

• Approximate Weight: ~ 90 kg

Key Technical Advantages

• 100% Drop-in Interchangeability: Mounting flanges, splined shafts, high-pressure working ports, and sensor interfaces are dimensionally identical to the original A4VG Series 32. Direct replacement is achieved without any need for adapter plates or hose rerouting.

• Heavy-Duty 400 Bar Reliability: Constructed with a high-strength swashplate, reinforced bearings, and precision-lapped bronze-alloy valve plates and piston shoes. This ensures optimal hydrodynamic lubrication under continuous high-pressure closed-loop operation, extending the pump’s service life.

• Precise EP Control with Pressure Cut-off: Equipped with a highly sensitive 24V proportional solenoid valve, enabling high-frequency, precise coordination with machine controllers for smooth, stepless acceleration. The integrated D1 pressure cut-off automatically destrokes the pump before the system reaches unsafe pressure limits, protecting downstream motors and piping.

• 100% Simulated Closed-Loop Testing: We do not rely on batch sampling. Every unit completes a full closed-circuit simulation run, including calibration of the EP current-to-displacement curve, peak pressure impulse tests, and charge pump pressure buildup validation to eliminate early-stage failures.

Application Areas:

Specifically designed for high-power hydrostatic drives, making it the premier choice for: heavy excavator swing drives, concrete mixer drum drives, road roller propulsion and vibration circuits, tunnel boring machines (TBM), crawler crane winches, and heavy-duty forestry/agricultural harvesters.

Expert Maintenance Tips

• Crucial Casing Priming: Prior to initial startup, the pump housing must be manually filled with clean hydraulic fluid through the highest case drain port to lubricate internal bearings. Never rely on the charge pump to self-prime an empty casing, as dry-running will instantly destroy the rotary group.

• Charge Circuit Filtration: Closed-loop systems are exceptionally sensitive to contamination. It is imperative to use a 10 μm absolute filter in the charge pump suction or pressure line to protect the sensitive proportional control spools.

• Monitor Case Pressure: The internal case drain pressure of the A4VG must never exceed 3 bar (absolute) during operation. Excessive case pressure will cause shaft seal blowout and disrupt the centering springs of the stroking piston. Ensure case drain lines are generously sized and routed directly to the reservoir without backpressure.