Rexroth A4VG250EP4D1 Piston Pump | A4VG250 High Pressure Axial Variable Pump Replacement

Genlu Hydraulic proudly introduces our heavy-duty hydrostatic transmission (HST) master plant—the A4VG250EP4D1/32R-NSD10F001SP-S high-pressure swashplate axial piston variable displacement pump. This series is fully engineered as a seamless, high-value, drop-in replacement for the classic Bosch Rexroth 32 series 250cc high-capacity matrix, adapting flawlessly to replace original main pumps across modern construction fleets and specialized ultra-tonnage off-road vehicles. Functioning as the absolute power heart of closed-loop industrial circuits, this pump houses a high-efficiency integrated charge pump, bi-directional cross-over high-pressure safety relief valves, and the advanced EP4 electro-proportional displacement control manifold. Genlu guarantees 100% Drop-in Interchangeability across standard SAE mounting interfaces, involute splined drive shafts, main fluid ports configurations, and the electronic control response/current curves compared to OEM Rexroth benchmarks. Every 250cc assembly undergoes a rigid 100% dynamic simulation test under alternating maximum loads within our modernized facility to certify outstanding volumetric efficiency under continuous heavy-duty field stresses.

Technical Specifications 

• Product Series: Rexroth A4VG Series 32 Platform Closed Circuit Axial Piston Variable Pump

• Full Structural Identifier: A4VG250EP4D1/32R-NSD10F001SP-S (Compatible with 71/90/110/140/250 series frame scaling)

• Geometric Displacement Configuration: 250 cc/rev

• Nominal Circuit Operating Pressure: 40.0 MPa (400 bar)

• Peak Transient Circuit Pressure: 45.0 MPa (450 bar)

• Integrated Boost Charging: Built-in premium internal-meshing gear charge pump

• Maximum Continuous Velocity: 2400 rpm (sustained under optimized intake and boost charge parameters)

• Control Methodology: EP4 (Electro-proportional control via proportional solenoids, translating electric input into displacement/direction shifts; equipped with Deutsch connectors)

• Direction of Rotation: R (Right Hand / Clockwise, looking directly from the drive shaft front face)

• Through-Drive Auxiliary Output: Code F00 (Standard non-through drive, or customizable for tandem auxiliary pump mounting)

• Drive Shaft Specification: Code S (High-rigidity standard SAE involute splined shaft interface)

• Nominal Weight Envelope: Approx. 143 kg

Key Technical Advantages:

• High-Dynamic EP4 Proportional Electro-Hydraulic Regulators: Utilizing the legendary Rexroth proportional solenoid layout coupled with internal precise hydraulic servo cylinders, the input control current corresponds linearly with the swashplate tilt angle and fluid flow output. Shifting response rates remain under 80 ms with minimal hysteresis and premium control repeatability, integrating perfectly with computerized vehicle logic networks.

• Ductile Iron Chassis via Finite Element Stress Mapping: To absorb the immense internal separation forces generated inside the 250cc rotating kit under a continuous 400 bar working pressure, the housing is precision-cast from premium ductile iron treated via thermal stress-relief. The main bearing seats and valving surfaces are milled in a single setup, checking micro-structural deflections during heavy-duty material tracking.

• 9-Piston Assembly with Stabilized Hydrostatic Slipper Balancing: The internal rotating kit implements a classic 9-piston block where the piston heads are nitrided and hard-coated, sliding on the swashplate via a precise hydrostatic oil film. This geometry ensures overall mechanical efficiency stays above 95% while drastically dampening high-frequency loop fluid pulsations and vibration harmonics.

• Integrated Multi-Functional Rear Valve Block Enclosure: The back valve cluster tightly combines cross-over overpressure relief capabilities with charge-makeup functions. It acts as a microsecond-fast fluid damping gate during explosive circuit spiking events, intercepting excessive load resistance to secure the downstream high-pressure hydraulic motor and plumbing lines.

Application Areas:

• Heavy Mining & Infrastructure Infrastructure: Ultra-tonnage open-pit excavators, heavy-duty hydraulic drilling rigs, rotary piling rig propulsion loops, and closed-circuit HST tracking for large industrial bulldozers.

• Heavy Duty Infrastructure & Road Maintenance: Primary closed-loop propulsion for high-capacity asphalt cold-milling planners, soil stabilizing mixers, and dual-side independent traction for highway pavers.

• Industrial Logistics & Offshore Marine Fleets: Drive networks for Self-Propelled Modular Transporters (SPMT) wheel hubs, high-capacity port cargo hoisting winches, and marine deck anchor windlass closed circuits.

Expert Maintenance Tips:

• Execute Mandatory Case and Servo Valve Air Venting (Critical Pre-Start Protocol): As a massive 250cc closed-circuit piston pump, initial installation requires completely flooding the housing cavity with fresh, deeply filtered hydraulic fluid via the highest physical casing drain opening ($T_1$ or $T_2$). Furthermore, because the EP4 controller relies on internal servo action, you must slightly loosen the air-vent plugs on the side of the servo cylinders, bump-start the motor, and bleed out trapped air pockets. Trapped air causes severe stroke response lag or destructive vehicle tracking jerking.

• Enforce Rigid Audits on Boost Charge Oil Pressure: A closed system must continuously depend on steady charge oil volume to stabilize low-pressure loop balancing and cool the inner rotating components. During low-idle engine initialization, check the pressure gauge port to confirm that the charge boost pressure registers steadily between 2.2 and 2.6 MPa (22-26 bar). Operating with inadequate charge pressure will cause immediate, catastrophic cavitation of the high-value 250cc block within moments.

• Maintain Low-Pressure Casing Drainage Routes and Premium Filtration: The dedicated case leakage drainage line from the A4VG250 must run independently back to the reservoir, discharging smoothly beneath the static fluid line with continuous internal case backpressures strictly limited under 0.2 MPa. Because closed loops continuously recirculate fluid between the pump and motor, tiny abrasive particles will initiate severe “chain-reaction wear.” Deploy high-capacity inline pressure filters rated at $\le 10\mu m$, ensuring system fluid cleanliness indices remain cleanly above ISO 18/16/13.