Rexroth A4VG250 Series Piston Pump | A4VG250EP2 A4VG250EP4 Closed Circuit Hydraulic Pump Replacement

Genlu Hydraulic proudly introduces our heavy-duty A4VG250 Series high-performance axial piston variable displacement pumps. This series is engineered as a seamless, premium, drop-in replacement for the classic Rexroth A4VG platform in its high-capacity 250cc frame size (including the specific Series 32 legacy part numbers such as R902207220, as well as elektro-hydraulic proportional controlled modules like A4VG250EP2DM1/32R-NZD10F001DH-S and A4VG250EP4D1/32L-NTD10F021DP). Serving as the heavy-duty power core for closed-circuit hydrostatic transmissions (HST), this pump monolithically integrates a high-volume internal gear charge pump, high-pressure swashplate servo cylinders, and bi-directional cross-over relief check valves. Genlu guarantees 100% Drop-in Interchangeability across standard SAE mounting configurations, splined drive shafts, through-drive auxiliary adapters, and the control electrical terminals/logic of the EP2/EP4 proportional valves compared to original Rexroth units. Every 250cc pump assembly undergoes strict 100% simulation testing under peak operational stresses to ensure exceptional control responsiveness and industrial-grade volumetric efficiency.

Technical Specifications 

• Product Series: Rexroth A4VG Series Axial Piston Variable Pump (Series 32)

• Core Displacement Specification: 250 cc/rev

• Cross-Reference Part Number: R902207220

• Represented Specific Configurations:

  • A4VG250EP2DM1/32R-NZD10F001DH-S (Clockwise rotation, EP2 electric proportional control with manual override)

  • A4VG250EP4D1/32L-NTD10F021DP (Counter-clockwise rotation, EP4 electric proportional control with high-dynamic response)

• Nominal Operating Pressure: 40 MPa (400 bar)

• Peak Transverse Pressure: 45 MPa (450 bar)

• Max Rotation Speed: 2400 rpm (under optimized charge pressure conditions)

• Max Theoretical Flow: Approx. 600 L/min (at rated input speed)

• Control Mechanism: EP2 / EP4 (Proportional electric control, utilizing 12V/24V proportional solenoids to regulate pilot pressure for positioning the internal servo piston)

• Through-Drive Configurations: Code D1 / DH / DP (Equipped with auxiliary coupling adapters to mount secondary high-pressure pumps or steering units)

• Sealing & Port Configurations: Viton / FKM sealing (N), standard SAE 4-bolt high-pressure flange port interfaces

Key Technical Advantages:

• High-Precision EP2/EP4 Proportional Electro-Hydraulic Swiveling: Outfitted with advanced dynamic proportional solenoids featuring mechanical or electrical feedback alignment, the assembly establishes a perfect linear ratio between controller current inputs and swashplate tilt angles. Delivering immense hydraulic shifting force, the servo cylinder response time takes only 80 ms, integrating perfectly into intelligent ECU closed-loop vehicle networking.

• Ultra-Rigid Monoblock Ductile Cast Iron Housing: Under continuous 400 bar full-capacity loading, the main drive shaft bearings and swashplate saddle face immense axial feedback forces. Genlu employs premium, high-density nodular iron optimized via Finite Element Analysis (FEA). This structural density completely eliminates micro-cracks and prevents instantaneous shaft deflection under cyclical strains.

• Advanced 9-Piston Rotary Kit with Hydrostatic Slip Balancing: The cylinder barrel houses a optimized 9-piston rotary layout backed by hydrostatically balanced slipper pads and a spherical valve plate. Under abrupt peak pressure shocks, the oil-film support underneath the slippers self-adjusts according to systemic resistance, cutting mechanical friction losses and dampening noise way below manufacturing limits.

• Monolithic Integrated Closed-Circuit Valve Block: The back of the main housing cleanly embeds the low-pressure charge control manifold and two multi-function high-pressure relief valves (acting as both overload thermal limits and circuit check valves). This integrated configuration removes external high-pressure hardlines, preventing leakage risks and minimizing vehicle chassis spatial envelopes.

Application Areas:

• Heavy Duty Infrastructure & Construction: High-capacity rotary drilling rigs undercarriage tracking, heavy road cold-milling planners, engineering crawler dozers, and wide-chassis asphalt concrete pavers.

• Heavy Lifting & Mining Extraction Networks: Primary hoisting winch loops for heavy-duty crawler cranes, underground fully hydraulic tunneling roadheaders, and surface mining transport trucks.

• Hydrostatic Special Logistics Machinery: Aircraft towbarless pushback tractors, seaport container straddle carriers, and multi-axle Self-Propelled Modular Transporters (SPMT) heavy drive axle powertrains.

Expert Maintenance Tips:

• Mandatory Servo Cylinder Air Venting (Critical Protocol): Upon finishing installation and flooding the pump housing via the highest drain port ($T_1$ or $T_2$), it is critical to address the precise EP control mechanism. Prior to the initial engine crank, loosen the air bleeding screws located on top of the servo cylinder blocks to purge air pockets. Trapped air causes severe stroke hunting, erratic displacement indexing, and vibration ripples.

• Monitor Charge Pressure and Proportional Current Signatures: Stable operation of any closed circuit relies on sufficient boost pressure (typically $\ge 2.2-2.6\text{ Mpa}$ at idle). If displacement shifting appears sluggish, verify that the current inputs running to the proportional solenoids are stable within their designated linear range (usually 200–600 mA), and connect a master gauge to the G-port for diagnostic mapping.

• Enforce High-Class Closed-Loop Cleanliness Standards: The rapid fluid recycling loop inherent in a 250cc closed circuit means micro-abrasive debris will cause severe damage to the EP spool valve clearances and the 9-piston rotary assembly. The circuit must deploy top-tier suction or high-pressure inline elements rated at $\le 10\mu m$. Maintain fluid cleanliness profiles strictly at ISO 18/16/13 or cleaner.