A4VG71HWDT1/32R-NZF02F041D Rexroth Variable Piston Pump 400 Bar

Product Overview

The Bosch Rexroth A4VG Series 32 is a variable displacement axial piston pump with a swash-plate design for closed-circuit hydrostatic transmissions.

The series covers nominal sizes from 28 to 250 cm³/rev. Bosch Rexroth’s official technical information specifies 400 bar nominal pressure and 450 bar maximum peak pressure for Series 32. The pump incorporates high-pressure relief/boost functions, an integrated boost pump for charge and control oil, and standard pressure cut-off protection.

The models covered here are:

• A4VG71HWDT1/32R-NZF02F041D
• A4VG125HDMT1/32R-NSF02F021S-S
• A4VG180HD9MT1/32R-NSD02F021S-S

For replacement applications, our engineering process focuses on in-place interchangeability, matching the original mounting interface, shaft configuration, rotation, hydraulic connections, control arrangement and pressure-related functions. Each replacement pump can undergo 100% simulated working-condition testing before delivery.

Technical Specifications

A4VG71HWDT1/32R-NZF02F041D

• Manufacturer: Bosch Rexroth
• Series: A4VG Series 32
• Type: Variable displacement axial piston pump
• Design: Swash-plate axial piston
• Circuit: Closed circuit
• Displacement: 71 cm³/rev
• Nominal pressure: 400 bar
• Maximum peak pressure: 450 bar
• Maximum speed at Vg max: 3,300 rpm
• Theoretical flow at maximum speed: 234 L/min
• Maximum input power at Δp = 400 bar: Approximately 156 kW
• Maximum torque at Δp = 400 bar: Approximately 451 Nm
• Control: HW hydraulic control, mechanical servo
• Rotation: Clockwise / right-hand
• Base weight without through-drive: Approximately 50 kg
• Associated material numbers found in product records: R902079984 / R902151251

Bosch Rexroth describes HW control as hydraulic mechanical-servo control. A feedback lever maintains pump displacement according to control-lever position, while the neutral-position switch can provide a safety function requiring zero flow during certain operating conditions.

A4VG125HDMT1/32R-NSF02F021S-S

• Manufacturer: Bosch Rexroth
• Series: A4VG Series 32
• Type: Variable displacement axial piston pump
• Design: Swash-plate axial piston
• Circuit: Closed circuit
• Displacement: 125 cm³/rev
• Nominal pressure: 400 bar
• Maximum peak pressure: 450 bar
• Maximum speed at Vg max: 2,850 rpm
• Theoretical flow at maximum speed: 356 L/min
• Maximum input power at Δp = 400 bar: Approximately 237 kW
• Maximum torque at Δp = 400 bar: Approximately 795 Nm
• Control: HD hydraulic proportional control, pilot-pressure related
• Rotation: Clockwise / right-hand
• Base weight without through-drive: Approximately 80 kg
• Associated material number: R909608256

The HD control principle uses an external pilot-pressure signal to operate the control valve and positioning cylinder, allowing pump displacement to respond proportionally to the pilot signal.

A4VG180HD9MT1/32R-NSD02F021S-S

• Manufacturer: Bosch Rexroth
• Series: A4VG Series 32
• Type: Variable displacement axial piston pump
• Design: Swash-plate axial piston
• Circuit: Closed circuit
• Displacement: 180 cm³/rev
• Nominal pressure: 400 bar
• Maximum peak pressure: 450 bar
• Maximum speed at Vg max: 2,500 rpm
• Theoretical flow at maximum speed: 450 L/min
• Maximum input power at Δp = 400 bar: Approximately 300 kW
• Maximum torque at Δp = 400 bar: Approximately 1,144 Nm
• Control: HD9 hydraulic proportional control variant
• Rotation: Clockwise / right-hand
• Base weight without through-drive: Approximately 101 kg
• Material number: R902193093

The exact HD9 configuration is listed in product records as a hydraulic proportional-control version of the A4VG180.

Key Technical Advantages

1. Variable Swash-Plate Architecture

The A4VG uses an axial-piston swash-plate mechanism. Changing the swash-plate angle changes piston stroke and therefore pump displacement. Moving through the neutral position allows smooth reversal of flow direction, which is fundamental for hydrostatic transmission applications.

2. Closed-Circuit High-Pressure Capability

The A4VG Series 32 is engineered for closed-circuit hydrostatic drives. High-pressure relief/boost functions help protect the transmission, while the integrated auxiliary pump supplies charge and control oil.

3. Multiple Hydraulic Control Technologies

The A4VG platform supports different control concepts, including HD, HW, EP, DA and EZ. The three specified models therefore require different control considerations:

• A4VG71HWDT1: HW mechanical-servo hydraulic control
• A4VG125HDMT1: HD pilot-pressure-related hydraulic proportional control
• A4VG180HD9MT1: HD9 hydraulic proportional-control variant

The complete model code must be retained when specifying a replacement pump.

4. High-Pressure Protection

Series 32 combines high-pressure protection with integrated pressure cut-off functionality. This protects the hydrostatic transmission from overload while allowing the pump to reduce displacement as operating conditions change.

5. High Power Density

At Δp = 400 bar, the official series data gives approximately 156 kW for A4VG71, 237 kW for A4VG125 and 300 kW for A4VG180. This makes the platform suitable for high-power hydrostatic transmission applications where hydraulic output must be delivered from a compact package.

6. Smooth Flow Reversal and Controllability

The swash-plate can be moved through neutral to change the direction of hydraulic flow smoothly. This characteristic is valuable in propulsion, traction, winching and other reversible hydrostatic drive systems.

7. Replacement Engineering Focused on Interchangeability

A true A4VG replacement requires more than matching nominal displacement. Critical checks include:

• Mounting flange
• Drive shaft and spline configuration
• Rotation
• Main hydraulic ports
• Charge/control connections
• Control unit
• Pressure cut-off configuration
• Valve-plate configuration
• Through-drive arrangement

Our replacement engineering process is therefore based on the complete Type Code and Material Number, followed by 100% simulated working-condition testing.

Application Areas

The A4VG Series 32 is suitable for closed-circuit hydrostatic applications such as:

• Excavators
• Concrete pump trucks
• Road construction machinery
• Road rollers and pavers
• Cranes
• Forklifts and special vehicles
• Agricultural machinery
• Mining equipment
• Winches
• Marine hydraulic drives
• High-power industrial hydrostatic transmissions

The A4VG180 configuration is also found in concrete-pump applications in publicly documented equipment specifications.

Final application selection must be confirmed against actual operating pressure, charge pressure, speed, engine power, control requirements and installation geometry.

Expert Maintenance Tips

1. Fill and Bleed the Pump Before Start-Up

Rexroth operating instructions require the axial piston unit to be properly filled with hydraulic fluid and air-bled before commissioning and after extended shutdown periods. This is particularly important in special installation positions where the unit can drain during long idle periods.

2. Keep the Case-Drain Circuit Correct

Case leakage must be routed back to the reservoir through an appropriate drain connection. Case pressure should be controlled carefully because excessive housing pressure can affect shaft sealing and internal lubrication conditions.

3. Verify Charge Pressure Before Adjusting the Control

In a closed-loop hydraulic system, charge pressure has a direct influence on inlet conditions, lubrication and cavitation protection. Abnormal noise, temperature rise or flow loss should therefore trigger checks of charge pressure and inlet conditions before changing the pressure cut-off setting.

4. Do Not Substitute HW and HD Controls

The A4VG71HWDT1 and the HD-controlled A4VG125/A4VG180 configurations use different control principles. HW is mechanical-servo hydraulic control, while HD is pilot-pressure-related proportional hydraulic control. A displacement-compatible pump with the wrong control architecture is not a true drop-in replacement.

5. Keep 400 bar and 450 bar Clearly Separated

For Series 32, 400 bar is the nominal pressure and 450 bar is the maximum peak pressure. The 450 bar figure should not be marketed as a continuous working-pressure rating.

6. Confirm the Installation Drawing for Final Replacement

The official technical data provides series-level displacement, pressure, speed and basic mass values, but final replacement approval should use the exact installation drawing and order confirmation for the specific Material Number. This is especially important where through-drive or special shaft/interface configurations are involved.

Engineering Verification Note

For the product page, the safest verified core data are:

• A4VG71: 71 cm³/rev / 400 bar nominal / 450 bar peak / 3300 rpm
• A4VG125: 125 cm³/rev / 400 bar nominal / 450 bar peak / 2850 rpm
• A4VG180: 180 cm³/rev / 400 bar nominal / 450 bar peak / 2500 rpm

These values come from Bosch Rexroth’s A4VG Series 32 technical data.

For the three complete codes, the verified control families are HW / HD / HD9, respectively. The exact suffixes should remain intact in the published product title because they identify configuration details that are relevant to replacement and cannot safely be removed in favor of only “A4VG71 / A4VG125 / A4VG180.”