Bosch Rexroth A4VG71 axial piston hydraulic pump

The Bosch Rexroth A4VG71 is a variable displacement, axial piston pump utilising a swashplate design. It is engineered predominantly for hydrostatic transmissions in closed circuits, meaning the fluid flows from the pump to the motor and then returns directly to the pump.

Key Specifications at a Glance

To understand its capability, we have to look at the numbers. The "71" in its name denotes its displacement size:

Displacement: 71cm³/rev

Nominal Pressure: 400 bar (5800 psi)

Maximum Pressure: 450 bar (6525 psi)

Control Types: Hydraulic, electrical, or manual proportional control

The Power of the Swashplate Design

The core mechanism relies on a rotating cylinder block containing pistons. As the block rotates, the pistons press against an inclined swashplate.

By adjusting the angle of this swashplate via the integrated control units, you alter the stroke length of the pistons. This allows for seamless, infinitely variable control over the fluid flow rate—from zero to maximum displacement—and even allows for a reversal of flow direction without changing the rotation of the input shaft.

Performance Benefits: Why the A4VG71 Stands Out

1. High Power Density

Space is at a premium in modern machinery. The A4VG71 delivers an exceptional power-to-weight ratio. It packs massive pressure capabilities into a relatively compact frame, allowing OEMs (Original Equipment Manufacturers) to design sleeker, lighter machines without sacrificing pulling or lifting power.

2. Integrated Auxiliary Features

One of the major advantages of the A4VG series is the integration of auxiliary components. The A4VG71 features:

Built-in boost pump (charge pump): Needed to supply make-up fluid, maintain minimum pressure in the low-pressure line, and provide cooling flow.

Integrated high-pressure relief valves: Protect the system from catastrophic pressure spikes.

Boost-pressure relief valves: Keep internal charge pressure stable.

3. Modular Control Flexibility

Whether your system relies on purely mechanical linkage or sophisticated electronic control units (ECUs), the A4VG71 adapts. It supports NV (Hydraulic pilot control), DG (Hydraulic control, direct operated), and EP (Electric control with proportional solenoid), making it highly compatible with modern IoT and automated machinery.

Real-World Applications and Examples

Where do you actually find the Bosch Rexroth A4VG71 hard at work? Its design makes it perfect for heavy-duty mobile hydraulics where precise speed and directional control are paramount.

Example 1: Earthmoving and Construction Equipment

In large wheel loaders and crawler excavators, the A4VG71 often drives the hydrostatic travel gear. When the operator pushes the joystick forward, the pump’s swashplate angles smoothly, providing the precise torque required to push into a pile of rock or accelerate smoothly across rough terrain.

Example 2: Agricultural Machinery

Modern combine harvesters require constant speed adjustments depending on crop density and terrain. The A4VG71 allows for infinitely variable ground speed control independent of the engine RPM, ensuring the harvesting mechanism runs at peak efficiency while the vehicle speed self-adjusts.

Pro-Tips for Maintenance and Longevity

To get the longest lifespan out of your A4VG71, engineering experts emphasise two critical factors: fluid cleanliness and proper commissioning.

Keep it Clean: Axial piston pumps operate with incredibly tight tolerances. Microscopic particles can cause scoring on the valve plate and pistons. Always use the recommended high-quality mineral oils and adhere strictly to filtration schedules (typically Beta ratio β_x ≥ 200).

Case Drain Management: Never start the pump without filling the housing with hydraulic fluid first. Running dry for even a few seconds will destroy the internal bearings and brass components. Ensure the case drain line is always routed directly back to the reservoir without restrictions.

For more information on the A4VG71 hydraulic pump, please visit https://www.baolilaihydraulic.com/product/.

Specifications

Selection Table