Rexroth A4VG Series Piston Pump Replacement | A4VG56 & A4VG40 Closed Circuit Pump

The Rexroth A4VG Series axial piston variable displacement pumps (specifically featuring A4VG56DA2D2/32R-NZC02F005S, A4VG56DA2D2/32R-NZC02F015S, and A4VG40HWD2/32R-NZC02F015S) by Chengyuan Hydraulic are high-performance power solutions purposefully engineered for hydrostatic closed-circuit transmissions. Designed as a 100% direct drop-in replacement for Bosch Rexroth Series 32 pumps, these units exactly match the OEM geometry, port designations, and hydraulic performance characteristics, allowing international B2B clients to swap units effortlessly while minimizing supply chain delays.

As the heartbeat of closed-circuit systems, the A4VG pump series fully integrates an auxiliary charge pump, high-pressure relief valves, and a charge pressure relief valve within its housing to streamline layout engineering. At Chengyuan, every single assembly undergoes 100% simulated working condition testing, guaranteeing that it will withstand intense 400 bar pressure spikes and severe dynamic shocks. Equipped with precision DA (speed-related automatic control) or HW (mechanical proportional servo control) modules, these pumps deliver optimal efficiency and structural stiffness for global off-highway and heavy industrial applications.

Technical Specifications

• Specific Model Codes: A4VG56DA2D2/32R-NZC02F005S / A4VG56DA2D2/32R-NZC02F015S / A4VG40HWD2/32R-NZC02F015S

• Product Series: A4VG Series 32

• Circuit Type: Closed Circuit

• Nominal Displacement: 40.0 cc/rev ($cm^3/rev$ for Size 40) / 56.0 cc/rev ($cm^3/rev$ for Size 56)

• Integrated Charge Pump Displacement: 10.6 cc/rev (Size 40) / 16.0 cc/rev (Size 56)

• Nominal Operating Pressure: 400 bar (40 MPa)

• Maximum Peak Pressure: 450 bar (45 MPa)

• Standard Charge Pressure Setting: 20 bar (adjustable range: 15 – 30 bar)

• Maximum Rated Speed: Up to 4000 rpm (Size 40) / 3600 rpm (Size 56) under working pressure

• Control Mechanisms: DA2 (Speed-related automatic control with positioning cylinder and inching valve capability); HW (Proportional control, hydraulic, mechanical servo feedback)

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

• Sealing Configuration: N (NBR nitrile rubber seals with high-resilience shaft ring)

• Shaft & Flange Specification: Z (SAE splined shaft for high torque capability) / C (SAE 2 or 4-bolt standard combination flange)

• Overload Protection: D (Integrated pressure cut-off valve standard to prevent sustained fluid thermal breakdown)

• Approximate Unit Weight: ~31.0 kg (Size 40) / ~38.0 kg (Size 56)

Key Technical Advantages

• Heavy-Duty Volumetric Resilience: The internal rotary group incorporates a high-grade bimetallic sintered cylinder block paired with precision-lapped piston shoes, retaining a volumetric efficiency above 96% even under continuous 400 bar loads. Cradle-style swashplate roller bearings effectively counter heavy radial and axial loading.

• Monoblock Closed-Circuit Architecture: The integrated design houses dual high-pressure relief valves with charge-feed functions and a charge pressure valve directly in the rear port plate. This heavily reduces external plumbing configurations, virtually removing external fluid leakage points while dampening circuit reversal vibration.

• Agile Control Response & Linearity: Both the DA2 speed-sensing control valve and the HW mechanical servo mechanism are finely calibrated for hydraulic dead-band stiffness. The DA setup perfectly translates engine RPM fluctuations into smooth displacement adjustments for vehicle traction, while the HW control offers exceptional operator stroke linearity.

• Comprehensive Simulation Testing: No pump leaves Chengyuan without enduring rigorous end-of-line simulation testing. The validation routine benchmarks structural case-drain volumes, transient response rates, high-speed charge stability, and cut-off safety parameters to verify OEM-tier operation out of the box.

Application Areas

The A4VG series serves as the primary hydrostatic travel drive engine for versatile off-highway machinery:

• Road & Infrastructure Machinery: Double-drum asphalt vibratory rollers (travel & vibration systems), asphalt pavers, skid steer loaders, and compact excavator track/swing loops.

• Agricultural & Forestry Equipment: Combine harvesters, heavy forage harvesters, and timber feller-bunchers.

• Material Handling & Mining: Heavy-capacity industrial forklifts, container reach stackers, underground LHDs (Load-Haul-Dump vehicles), and mining utility trucks.

Expert Maintenance Tips

• Pre-Commissioning Case Filling & Bleeding: Because closed-circuit systems can easily trap air pockets, it is mandatory to fill the pump housing via the highest available drain port (Port L1 or L2) with micro-filtered oil before cranking. Jog the engine briefly and utilize the MA/MB high-pressure ports to vent lingering air from the main loop to prevent dry friction damage.

• Charge Pressure Verification: During initial commissioning, always hook up a pressure gauge to the charge test port (Port G). Under neutral conditions and peak pressure reversal cycles, the charge pressure must never dip below 15 bar; inadequate charge pressure will cause fatal cavitation damage across the piston shoes.

• Strict Loop Hygiene Regulations: Closed circuits continually recirculate oil, meaning trapped contaminants will repeatedly pass through vital tolerances. It is highly recommended to install a $10 \mu m$ absolute filtration circuit (complete with electrical clogging indicators) to preserve fluid cleanliness levels at or cleaner than ISO 4406 19/16/13.