Rexroth A4VG Series Piston Pump | A4VG250 A4VG90 A4VG40 Closed Circuit Hydraulic Pump Replacement

Genlu Hydraulic proudly introduces our A4VG Series (covering 28, 40, 56, 71, 90, 125, 180, and 250 cc/rev displacement modules) high-performance axial piston variable displacement pumps. This series is engineered as a seamless, premium replacement for the classic Rexroth A4VG platform (specifically Series 32 and Series 40) dedicated to closed-circuit hydrostatic transmissions (HST). Serving as the core powertrain component for heavy-duty mobile machinery, this pump series integrates a boost/charge pump, closed-loop high-pressure relief valves, a charge pressure relief valve, and a highly responsive elektro-hydraulic variable mechanism. Genlu guarantees 100% Drop-in Interchangeability across standard SAE mounting flanges, splined drive shafts, through-drive auxiliary configurations, and control valve terminal profiles compared to original Rexroth units. Every A4VG pump undergoes rigorous 100% simulation testing under peak operational stresses to ensure rapid dynamic swivel control, minimal internal bypass leakage, and superb volumetric efficiency.

Technical Specifications 

• Product Series: Rexroth A4VG Series Axial Piston Variable Pump (For Closed Circuits)

• Complete Model Identifier: A4VG250HD3D1/32R-NSD10F00

• Displacement Profile: 250 cc/rev (Available across 28cc to 250cc full scale)

• Nominal Working Pressure: 40 MPa (400 bar)

• Peak Operating Pressure: 45 MPa (450 bar)

• Max Rotation Speed: 2400 rpm (at absolute displacement of 250cc; smaller frame sizes allow higher rotational velocity)

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

• Control Mechanism: HD3 (Proportional hydraulic control, pilot-operated via electronic proportional pressure reducing valves)

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

• Design Generation: Series 32 (fully aligned with original Series 32 configuration drawings)

• Auxiliary Charge System: Integrated internal gear boost pump with built-in limitation protection

Key Technical Advantages:

• HD3 High-Dynamic Linear Control: Outfitted with dual proportional solenoid pressure-reducing valves and a hydraulic servo positioning block, it provides an exceptional linear current-to-swashplate angle ratio. Shifting response times take only tens of milliseconds, ensuring perfect harmony with modern ECU programming.

• High-Density Nodular Iron Structural Integrity: The main casing is cast from high-strength nodular iron with induction-hardened fluid tracks. This layout absorbs continuous 400 bar load profiles and 450 bar transient peaks without developing micro-fissures or bore ovalization, securing permanent component alignment.

• Fully Integrated Hydrostatic Module Block: The inner housing monolithically incorporates two high-pressure multifunction valves (combining pressure cross-relief with boost check capabilities) and a charge pressure control valve, eliminating complex external lines and optimizing leak-free reliability.

• Robust Swashplate Saddle Bearings: The swashplate is balanced by a high-capacity saddle bearing architecture. Paired with a hydro-mechanically optimized 9-piston rotary kit, it effectively cushions pressure ripples during direction reversals, scaling down operational noise far below strict manufacturing regulations.

Application Areas:

• Heavy Duty Mobile Machinery: Rotary drilling rigs crawler drives, large asphalt pavers, compacting road rollers, high-capacity concrete transit mixers, and wheel loader hydrostatic drivetrains.

• Lifting & Material Handling Fleet: Main winch control networks for heavy-duty crawler cranes and slewing loops for large truck cranes.

• High-Capacity Agriculture & Forestry: Front-axle traction drives for heavy combine harvesters and hydrostatic propulsion for large logging forwarders.

Expert Maintenance Tips:

• Mandatory Initial Pre-Priming (Critical Protocol): Upon finishing installation and prior to cranking the engine, the pump casing must be fully flooded with clean hydraulic oil through the highest case drain port. Additionally, due to the unique properties of closed circuits, the charge lines and high-pressure ports must be bled of air pockets to prevent dry-scuffing destruction.

• Boost Pressure Monitoring Diagnostics: Closed loops rely heavily on internal boost pressure for shifting signal actuation and thermal fluid exchange. If you observe sluggish directional indexing or cavitation-like clicking, immediately link a gauge to the G-port to verify if charge pressure matches technical specifications (typically 20-30 bar).

• Enforce Maximum Closed-Loop Filtration: The A4VG servo pilot block and multifunction valves are highly vulnerable to particulate contamination. The circuit configuration must run premium charge suction filtration (filtration rating $\le 10\mu m$) or high-pressure pressure-line inline elements. Maintain oil cleanliness strictly at ISO 18/16/13 (NAS Class 7) or cleaner.