A4VG Piston Pump | Rexroth A4VG110 A4VG250 A4VG280 Replacement

Genlu Hydraulic specializes in the continuous engineering and production of heavy-duty, industrial, and mobile-grade high-pressure axial piston variable pumps. The A4VG Series High-Pressure Closed-Circuit Hydraulic Piston Pump is precision-built as a rugged, high-performance, and 100% drop-in interchangeable alternative to the global industry benchmark Rexroth classic 32-series closed-circuit variable piston pump lines. We provide comprehensive order support for standard displacements, prominently covering frame configurations including A4VG45, A4VG65, A4VG85, A4VG110, A4VG145, A4VG175, A4VG210, and A4VG280, as well as the specialized large-displacement frame A4VG250. We offer extensive support for factory cross-referencing of premium builds such as the specific model code A4VG250EP4DT1/32R-NZD10N001EH-S and material SKU R902128455.

Serving as the fluid core of Hydrostatic Transmission (HST) systems, the main pump’s displacement control linearity, high-pressure volumetric stability, and integrated charge boost pressure define the traction capacity and exact positioning limits of heavy vehicles. Genlu’s A4VG closed-loop pumps match the original technical data manuals across all physical mounting envelopes, standard splined drive shafts, high-pressure flange ports, and the sophisticated EP4 (Electric Proportional Control with proportional solenoids and emergency manual overrides) control logic. Prior to final dispatch, every unit undergoes 100% Full-Simulation Condition Testing on digitized diagnostic benches to guarantee responsive control valves, stable boost parameters, and ultra-low internal leakage under continuous pressures up to 450 bar.

Technical Specifications 

• Product Line: A4VG Series Closed-Circuit High-Pressure Axial Piston Variable Displacement Pump

• Exact Designated Part Number & Model Build: A4VG250EP4DT1/32R-NZD10N001EH-S (SKU: R902128455)

• Geometric Displacement Profile Matrix:

  • A4VG45 (45.0 $cc/rev$) / A4VG65 (65.0 $cc/rev$) / A4VG85 (85.0 $cc/rev$)

  • A4VG110 (110.0 $cc/rev$) / A4VG145 (145.0 $cc/rev$) / A4VG175 (175.0 $cc/rev$)

  • A4VG210 (210.0 $cc/rev$) / A4VG250 (250.0 $cc/rev$) / A4VG280 (280.0 $cc/rev$)

• Nominal Continuous Operating Pressure: 400 bar (40.0 MPa / 5800 psi)

• Maximum Intermittent Peak Pressure: 450 bar (45.0 MPa / 6525 psi)

• Control Mechanism Profile: EP4 – Electric Proportional Control (24V DC, proportional proportional solenoids with mechanical emergency manual override and integrated limit switches)

• Thru-Drive Auxiliary Adaptor: T1 – Equipped with rigid structural thru-drive for tandem configuration coupling (e.g., coupling auxiliary gear pumps or secondary piston units)

• Drive Shaft Directional Rotation: R – Clockwise (CW, looking from the front shaft end extension)

• Design Generation Sequence: 32 Series (Optimized rotating group and fluid timing geometry)

• Sealing Configuration Compound: N – NBR Nitrile rubber compound sealing arrangement (highly resistant to continuous heavy pressure pressure waves)

• Auxiliary Boost Circuit Integration: Outfitted with an integral large-displacement gear-type Charge Pump including low-pressure charge relief validation

Key Technical Advantages:

• All-in-One Compact Architecture for Closed Loops: The internal body of the A4VG pump integrates all critical closed-loop valves, including dual high-pressure cross-port relief valves (with integrated boost functions), a low-pressure charge relief valve, and an independent gear charge pump. This high integration eliminates excessive external plumbing and manifold blocks, providing up to 450 bar of peak power while optimizing installation space and preventing vibration-induced line leaks.

• EP4 Intelligent Proportional Control with Millisecond Response: Equipped with the advanced EP4 regulator, the unit utilizes precision proportional solenoids and hydraulic servo spool positioning to control a large-diameter, dual-acting stroking piston. Under a standard 24V analog command signal, the swashplate adjusts with millisecond-scale responsiveness. An internal hydraulic negative feedback mechanism keeps displacement delivery linear to the control current, ensuring smooth, precise machine tracking.

• 9-Piston Rotating Kits Machined to Micron Clearances for 96% Volumetric Efficiency: The internal cylinder blocks and pistons undergo vacuum hardening and specialized nitrocarburizing treatments. Paired with spherically lapped valve plates, the piston-to-bore clearances are held to micron-scale tolerances. This design minimizes internal cross-port leakage during continuous high-pressure reversals, keeping the continuous operational volumetric efficiency steadily above 96%.

• Heavy Duty Ductile Iron Casing with Low-Noise Flow Dynamics: The main housing is cast from high-tensile ductile iron, with structural thickness optimized at major bearing journals via 3D geometric modeling. The fluid chambers at both the intake and discharge ports are shaped using computational fluid dynamics (CFD) to lower resistance, significantly dampening pressure pulsations caused by closed-loop frequency shifts and keeping airborne noise within strict industrial standards.

Application Areas:

• Heavy Hydrostatic Mobile Travel Drives (HST Circuits): Main closed-loop propulsion pumps for high-capacity dual-track hydraulic excavators, large wheel loaders, heavy asphalt pavers, and tandem road rollers.

• Mining, Geotechnical Tunnelling & Specialized Concrete Rigs: High-torque rotary head drives for piling rigs, cutter auxiliary advancement circuits for tunnel boring machines (TBM), and primary high-output hydraulic drives for concrete pump trucks.

• Heavy-Duty Maritime Deck Crane & Port Handling Equipment: Primary closed-loop hydraulic power supply for container reach stackers, heavy shipboard gantry winches, and luffing mechanism loops.

Expert Maintenance Tips:

• Mandatory Closed-Loop Housing Pre-Filling Through Highest Drain Port: Because the A4VG series operates within high-load closed circuits, the swashplate and piston shoes require immediate lubrication at startup. Before starting the prime mover for the first time, fill the pump housing completely with fresh, filtered hydraulic fluid through the highest available case drain port until it overflows without air bubbles. Running the pump dry while waiting 3-5 seconds for the charge pump to build pressure can cause immediate, irreversible scoring of the main bearings and piston shoes.

• Continuous Charge Pressure & Multifunction Valve Monitoring: During operation, closely monitor the low-pressure charge circuit, which should maintain a steady 20 to 30 bar gauge pressure under normal conditions. If charge pressure drops below the factory minimum, stop operation immediately to prevent severe fluid cavitation and catastrophic rotating group failure. Inspect the integrated multifunction high-pressure relief valves and the charge relief valve for particle contamination or spring fatigue.

• Shielded Proportional Solenoid (EP4) Wiring Against Electromagnetic Interference: For the A4VG250EP4 control solenoids, use twin-core twisted shielded cabling for all 24V DC command lines. Because closed-circuit pumps often operate near high-output diesel engines and alternator arrays, unshielded lines can pick up electromagnetic interference. This interference can cause the proportional solenoids to vibrate, leading to erratic pressure fluctuations or jerky machine movements.