Rexroth A4VG71DA1D2/32R-NAF02F001BP Hydraulic Piston Pump

Genlu Hydraulic excels as a world-class engineered fluid power component manufacturer, heavy-duty closed-loop hydrostatic transmission (HST) expert, and strategic B2B global supplier of premium axial piston pumps. The A4VG71DA1D2/32R-NAF02F001BP High-Pressure Axial Piston Variable Displacement Pump—along with its sibling displacements A4VG28, A4VG56, A4VG71, and A4VG125—is custom-engineered and manufactured as a premium, structurally reinforced, and 100% drop-in interchangeable high-tier alternative to the definitive global industry standard: the Bosch Rexroth 32 Series closed-loop piston pumps. We maintain dedicated manufacturing lines and robust component stocks for this platform to support application-critical environments in asphalt pavers, concrete transit mixers, heavy road cold-milling equipment, and rotary drilling rig winches.

Operating as the primary power-generation core within closed hydrostatic circuits, this pump manages continuous high-pressure operations (nominal 350 bar, with intermittent shock peaks up to 400 bar) while seamlessly integrating an embedded charge pump, high-pressure relief valves, charge pressure overflow valves, and an advanced DA speed-related hydraulic proportional control valve block. Genlu’s Rexroth-style replacement assemblies conform exactly to the metallurgical, geometric, and fluid-power specifications detailed in original factory technical manuals. We guarantee absolute drop-in compatibility across standard SAE mounting flanges, involute splined drive shafts, SAE split-flange working ports, and internal “9-piston bimetal rotating cylinder groups.” Prior to final warehouse dispatch release, every single pump assembly undergoes 100% Full-Simulation Condition Testing on digitized, multi-channel closed-loop test benches to verify volumetric delivery, control pressure responsiveness, and precise relief valve cracking points under extreme thermal load.

Technical Specifications

• Product Model Configuration: A4VG71DA1D2/32R-NAF02F001BP (100% cross-compatible with Bosch Rexroth Series 32)

• Geometric Displacement Metric: 71.0 $cc/rev$ nominal volume (Comprehensive series covers 28cc, 56cc, 71cc, and 125cc options)

• Control Device Architecture Code: DA1 — Speed-related hydraulic proportional control (Output displacement scales proportionally with input driving speed, featuring mechanical-hydraulic linkage and inching capabilities)

• Control Regulation Valve Spec: D2 — Configured with dual proportional control solenoids (Available in 12V or 24V DC), providing bidirectional stroking management

• Series Designation & Rotational Profile: Series 32 design platform; R-Code designating standard Clockwise single-direction right-hand rotation

• Elastomer Compound Configuration: N — NBR (Nitrile butadiene rubber compounds, paired with premium FKM high-speed shaft lip seals)

• Drive Shaft Spline Type: A — Standard high-torque Involute Splined Shaft (Conforming to ANSI B92.1a)

• Mounting Flange Geometry: F — Standard heavy-duty SAE 4-bolt mounting flange (Conforming to SAE J744 specifications)

• Service Fluid Port Layout: 02 — Main working ports A and B configured as SAE split flanges positioned on the sides of the housing (Metric fastening threads)

• Through-Drive & Auxiliary Configuration: F001 — Integrated standard displacement auxiliary charge pump, sealed rear cover layout without rear through-drive shaft extension

• High-Pressure Relief Valve Profile: B — Equipped with dual high-pressure relief valves integrated with charge check valves (Standard factory cracking pressure calibrated at 420 bar)

• Charge Overflow Valve Parameter: P — Integrated standard charge pressure relief valve (Base pressure setting calibrated at 20-25 bar)

• Continuous Rated Operating Pressure Boundary: 350 bar (35 MPa / 5075 PSI)

• Maximum Intermittent Peak Pressure Bound: Rated up to 400 bar (40 MPa / 5800 PSI) for transient shock load protection

• Maximum Permissible Continuous Rotational Velocity: 3300 RPM (Subject to meeting minimum charge inlet suction parameters)

• Total Pump Assembly Dry Mass: Approximately 50.0 kg (Utilizing a high-rigidity monolithic ductile iron heavy-walled casting)

Key Technical Advantages:

• Monoblock Ductile Iron Reinforced Housing Metallurgy: The main pump casing is cast from premium-grade, high-tensile ductile iron (QT600) in a heavy-walled monolithic layout. This structure minimizes micro-casing deflection under continuous 400 bar peak pressure spikes, keeping the large swashplate cradle bearings and hydraulic cradle-servo pistons aligned to prevent edge loading and binding.

• Vacuum-Sintered Bimetal Cylinder Block with 9-Piston Topology: The rotating cylinder barrel face features a high-strength forged steel core vacuum-sintered with an anti-friction bronze layer. The 9-piston arrangement reduces hydraulic fluid pulsations by over 35% compared to traditional designs. This setup maintains consistent volumetric efficiency above 96% under high-pressure operations while lowering high-frequency system noise.

• Integrated “Five-in-One” Modular Closed-Loop Valve Center: The rear port block integrates bidirectional high-pressure relief valves, charge check valves, a charge pressure overflow valve, and the DA pilot control block. This design eliminates external high-pressure piping connections to reduce leak points. It provides millisecond-level pressure clipping during heavy inertial braking to protect hydrostatic motors from water-hammer shocks.

• DA Speed-Related Control Logic to Prevent Engine Stalling: The integrated DA control mechanism generates pilot pressure based on input driving speed (engine RPM). If the prime mover encounters a sudden load surge and engine RPM drops, the DA valve automatically de-strokes the pump’s swashplate angle. This action matches the pump’s torque absorption with the engine’s torque curve, preventing engine stall during heavy hill-climbing or digging operations.

Application Areas:

• High-Tier Municipal Road and Paving Equipment: Closed-loop independent hydrostatic ground drives for large asphalt pavers and main propulsion circuits for road cold-milling machines.

• Heavy Construction Infrastructure and Piling Rigs: Closed-loop auxiliary winches for rotary drilling rigs and primary high-压 twin-pump configurations for concrete boom pumps.

• Specialized Mobile Heavy Transport Vehicles: High-capacity hydrostatic drum drives (HST) for 12-16 cubic meter transit mixers, reach stackers, and heavy-duty airport tow tractors.

Expert Maintenance Tips:

• Mandatory Dual-Port Casing Priming Protocol Prior to Power-Up: The swashplate cradle bearings and servo piston mechanisms in the A4VG71 depend on case fluid immersion for lubrication. Before initial commissioning or starting after long shutdowns, fill the pump housing with at least 2.5 liters of clean hydraulic oil through the highest case drain port ($T_1$ or $T_2$) and manually rotate the drive shaft at least 5 turns. Running dry will score the piston slipper-to-swashplate interface during the first few seconds of operation.

• Dynamic Closed-Loop Charge Pressure Monitoring Requirement: Insufficient charge pressure within closed-loop systems causes piston shoe lift and cavitation erosion on the low-pressure side. Install a pressure gauge at test port $M_H$ to ensure charge pressure remains above 20 bar at low idle and 24 bar at full operating RPM. If charge pressure drops below these levels, shut down the system immediately to inspect the suction filter and charge relief valve.

• Precise Calibration of the DA Inching Adjustment Screw: This pump includes an inching function (via port N) that allows operators to modulate pilot pressure using a foot pedal for low-speed maneuvering. When tuning vehicle response, turn the DA inching adjustment screw no more than 1/4 turn per adjustment. Clockwise adjustments quicken displacement response, while counter-clockwise adjustments delay it. Always monitor the pilot pressure curve at test port $M_B$ during adjustment to ensure smooth vehicle launch control.