Rexroth A4VG Series Closed Loop Piston Pump A4VG56 A4VG125 A4VG180

The heavy-duty A4VG Series High-Pressure Closed-Loop Axial Piston Variable Pumps (encompassing premium hydrostatic marketplace designations A4VG56DA2D2/32R-NZC02F025FH-S, A4VG125DA2DM2/32R-NSF02F071DC, and the massive power A4VG180EP4DT1/32LN2D02 N001), manufactured by Chengyuan Hydraulic, stand as exceptional fluid power units engineered for 100% direct drop-in interchangeability inside global B2B mobile equipment hydrostatic transmissions (HST). Built to strict structural guidelines that match the original Bosch Rexroth Series 32 technical manuals, this matrix perfectly replicates factory mounting pilots, high-torque SAE/DIN drive shafts, integrated manifold bolt layouts, and boost charging port alignments. Mobile plant operations and heavy fleet engineering teams can execute rapid, immediate on-site component changes with zero modifications to pre-existing high-pressure piping hoses, auxiliary pilot valves, or electronic control networks.

Operating as the self-contained “power center” for high-pressure closed loops, the A4VG series integrates an internal charge pump, dual high-pressure cross-port relief safety valves, and a dedicated boost regulator within a single, highly refined package to handle smooth variable speed control and seamless forward/reverse directional switching. At Chengyuan, zero environmental risks are left unmanaged; every single closed-circuit pump completing production successfully clears our 100% rigorous dynamic simulation test bench criteria. Subjected to continuous testing up to its nominal 350 bar load and 400 bar peak structural pressure, each pump is strictly evaluated for DA (speed-related hydraulic) and EP (proportional electric) swashplate stroke reaction times, case drain leakage profiles across the entire thermal bandwidth, and anti-shock deceleration stability before earning its quality certificate.

Technical Specifications

• Product Series Classification: A4VG Series Variable Displacement Swashplate Axial Piston Pump (Closed-Loop Specialized)

• Technical Generation Matrix: Series 32 Design Edition

• Nominal Continuous Operating Pressure: 350 bar (35 MPa)

• Maximum Permissible Peak Pressure: 400 bar (40 MPa continuous shock-load threshold)

• Integrated Charge Pump Pressure Baseline: Standard factory calibration spanning 20 bar to 30 bar

• Recommended System Cleanliness Boundary: Strictly matching or exceeding ISO 4406 20/18/15 criteria to mitigate contaminant accumulation in closed circuits

• Model-Specific Nomenclature & Engineering Metrics (Catalog Verified):

  • Part Designation: A4VG56DA2D2/32R-NZC02F025FH-S

  • Geometric Displacement Scale: 56 cc/rev ($cm^3/rev$)

  • Control Configuration DA2D2: Speed-related hydraulic control equipped with a manual emergency override lever and dedicated mechanical spring centering. The pump displacement tracks engine RPM, matching requirements for road rollers and utility wheel loaders.

  • Drive Extensions: Letter R signifies right-hand (clockwise) rotation; designation NZC02F025 denotes SAE standard high-torque involute splines and matching suction flanges.

  • Through Drive Capacity: Suffix FH-S embeds a reinforced through-drive shaft adapter, allowing tandem coupling of a secondary steering pump or auxiliary gear system.

  • Maximum Permissible Velocity: 3600 rpm; Net Weight: Approx 38.0 kg.

  • Part Designation: A4VG125DA2DM2/32R-NSF02F071DC

  • Geometric Displacement Scale: 125 cc/rev ($cm^3/rev$)

  • Control Configuration DA2DM2: Speed-related hydraulic control incorporating a specialized electrical cut-off solenoid module. Suffix DM2 specifies high-recovery trim adjustments to optimize heavy vehicular drawbar pull.

  • Drive & Auxiliary Porting: Code NSF02F071DC registers a heavy-duty splined main shaft with an integrated 071-size through-drive rear port for high-delivery auxiliary steering hookups.

  • Maximum Permissible Velocity: 2850 rpm; Net Weight: Approx 78.0 kg.

  • Part Designation: A4VG180EP4DT1/32LN2D02 N001

  • Geometric Displacement Scale: 180 cc/rev ($cm^3/rev$) (Ultra-capacity heavy HST main pump)

  • Control Configuration EP4DT1: Proportional electric control utilizing dual 24V DC solenoids. Input current correlates linearly with swashplate angle for fluid metering control, augmented by the DT1 hardware configuration for automated electronic safety override protection.

  • Special Hardware Suffix: Code LN2D02 registers specialized case-drain orientation parameters with tailored cross-port pressure settings; suffix N001 defines custom modifications matching specific heavy-duty OEM mobile platforms.

  • Maximum Permissible Velocity: 2500 rpm; Net Weight: Approx 101.0 kg.

Key Technical Advantages

• Micron-Precision Lapped Pistons with Hydrostatically Balanced Slippers: Incorporates a balanced 9-piston rotating group. Each piston undergoes high-precision centerless grinding and mirror polishing, matching with high-strength bronze alloy slippers. Micro-channels within the slippers establish a $\le 3\,\mu\text{m}$ hydrostatic oil film over the swashplate under 350 bar continuous pressure, boosting mechanical efficiency up to $\ge 95\%$.

• Vacuum-Sintered Bi-Metal Timing Face with Cavitation Dampening: The cylinder face relies on a multi-axis lapped, bi-metal vacuum-sintered valve plate. This robust layer resists high-velocity fluid erosion and controls micro-pitting caused by flow reversals typical in closed-loop transmissions. This setup effectively mitigates fluid hammer and limits internal cross-port leakage.

• Monoblock Integrated Multi-Functional Control Manifold: The upper pump housing directly integrates the auxiliary charge pump, cross-port safety relief valves, and pilot control modules (such as the DA regulator or EP proportional electronic solenoids). This compact manifold layout minimizes external plumbing connections, eliminates potential leak paths, and drops pilot signal hysteresis close to zero.

• FEA-Reinforced High-Tensile Ductile Iron Casting Core: The core pump frame is cast from high-density, stress-relieved ductile iron, with internal galleries structurally enhanced using 3D finite element analysis (FEA). This rigid framework contains micro-yielding under continuous 400 bar load shocks, preserving precise同轴轴同轴度 (coaxial alignment) across internal cradle bearings and the drive shaft assembly.

Application Areas

The A4VG series closed-loop variable pumps, recognized for their power density, precise step-less speed regulation, and structural resilience, are widely integrated as primary hydrostatic propulsion centers across severe-duty mobile machinery:

• Heavy-Duty Hydrostatic Mobile Machinery: Main drive transmissions for high-pressure dual-drum vibratory compactors, heavy wheel loaders, and independent dual-track hydrostatic crawlers/bulldozers.

• Road Construction Equipment & Utility Fleets: Constant-velocity drum drives for heavy concrete mixers (e.g., A4VG56 paired with A2FM56 motor arrays), cold milling machinery, highway pavers, and heavy breakdown recovery vehicles.

• High-Yield Agricultural & Modern Forestry Harvesters: Hydrostatic travel propulsion for high-throughput grain combines, sugar cane harvesters, heavy-duty forwarders, and industrial logging vehicles.

Expert Maintenance Tips

• Mandatory Pre-Commissioning Housing and Boost Loop Priming: Due to the complex internal galleries and integrated pilot actuators of closed-loop architecture, always fill the pump enclosure with fresh, filtered hydraulic fluid via the highest case drain port before initial startup. Additionally, prime the auxiliary charge pump intake lines to prevent dry friction during startup. Operating the unit dry will score the internal valve plate and slipper faces within seconds.

• Enforce Separation of Loops and Monitor Filtration Metrics: Closed-loop systems recirculate fluid continuously, meaning microscopic metal wear particles are amplified rather than settled. Regularly replace the high-efficiency charge-line filter elements, and ensure the electrical clogging indicator switches are fully integrated. Ensure all replenishment fluid passes through an absolute filtering screen of at least $5\,\mu\text{m}$ to maintain an oil cleanliness standard of ISO 4406 19/17/14 or better.

• Keep Case Drain Line Back-Pressure Within Safe Operating Limits: The pump’s internal leakage must be piped independently back to the reservoir, terminating below the minimum fluid line. Never couple this drain path with check valves or main system return lines. Ensure continuous running case back-pressure stays beneath $\le 1.2$ bar (with brief cold-start peaks not exceeding 2.0 bar) to protect the input shaft lip seals from blowing out and prevent parasitic pressure from disrupting the DA or EP pilot control pistons.