Bosch Rexroth A4VSO40 axial piston hydraulic pump

The A4VSO40 is a variable displacement axial piston pump designed for hydrostatic drives in open-circuit hydraulic systems. It is produced by Bosch Rexroth AG, headquartered in Lohr am Main, Germany, one of the world's leading manufacturers of hydraulic components and drive technology.

The pump operates in an open circuit: hydraulic fluid is drawn from a reservoir, pressurized, delivered to the actuator or system, and returned to the tank. This is the standard arrangement for industrial presses, machine tools, and stationary power units, as opposed to closed-circuit operation more common in mobile hydrostatic transmissions.

Control Options for the A4VSO40

One of the A4VSO platform's strongest selling points is its extensive menu of control devices. Available controllers include DR, DFR, DRG, LR, LR2G, LR2N, LR2D, HS4, EO2, and HSE variants. Each serves a different control philosophy. Here are the most commonly specified for Size 40 applications:

DR-Pressure Compensator

The DR control maintains a constant system pressure regardless of flow demand. When system pressure reaches the set point, the swash plate destroke reduces displacement until flow matches what the load actually consumes. This is the most straightforward control for applications with variable flow demands and a fixed maximum pressure-hydraulic clamping circuits being a classic example.

DFR-Pressure/Flow Combined Control

The DFR (and DFR1 variant) combines pressure compensation with an external flow command signal, typically from a proportional valve. The DFR1 variant eliminates the connection from the XF port to the tank and allows minimum and maximum swivel angle limitation, mechanically adjustable to 50% of maximum displacement. The DFR is well-suited for load-sensing systems where the pump responds dynamically to both pressure and flow setpoints.

LR / LR2-Power (Hyperbolic) Control

The LR family implements constant power control, sometimes called hyperbolic control because the pressure-flow curve traces a hyperbola on a P-Q diagram. As pressure rises, the control reduces displacement to keep input power approximately constant. This protects the prime mover from overload across varying load conditions. The LR2 adds a second control stage, allowing two-range power settings on a single pump.

EM / MA-Electro-Hydraulic and Manual Controls

For applications requiring proportional electrical command, the EM control interfaces with standard analog or fieldbus signals. The MA (manual adjustment) provides a simple mechanical handwheel for test rigs or applications where electronic control isn't available.

Industrial Applications

Plastic Injection Molding

The A4VSO series is employed in plastic injection molding, metal forming, heavy machines, and other hydraulic systems demanding high performance. In injection molding specifically, the A4VSO40 is sized for smaller tonnage machines, typically in the 50 to 150-ton clamping force range, where precise pressure control during the pack-and-hold phase directly affects part quality. The pump's rapid swash plate response means it can follow the fast pressure transients of the injection cycle without hunting or overshoot.

Metal Forming and Stamping Presses

Metalforming presses demand both high flow on the approach stroke and sustained high pressure at the clamp. The A4VSO40's 400 bar peak pressure rating means it can handle the demanding pressure spikes of deep-draw or blanking operations. The power control (LR) variant is particularly useful here: as the press builds clamp force and pressure rises, the pump automatically backs off displacement to avoid overloading the motor during the high-force hold phase.

Machine Tool Hydraulics

CNC machining centers and transfer lines use the A4VSO40 in tool clamping, rotary table clamping, and workholding applications. The low noise level matters in these environments-operators work in proximity to machine tools, and cumulative noise exposure is a real concern. Rexroth's axial piston design with its precisely timed valve plate is demonstrably quieter than equivalent gear pump solutions at the same power level.

Hydraulic Power Units and Test Rigs

Test stands for hydraulic component testing routinely use the A4VSO40 as the primary pressure source. The combination of 350 bar continuous pressure, variable displacement for energy efficiency during idle periods, and a wide range of control options makes it ideal for flexible test cell architectures. The visual swivel angle indicator-a standard feature of the A4VSO series-is particularly useful in test environments where operators need a quick confirmation of pump state without instrumentation.

Steel, Marine, and Ceramic Industries

The A4VSO finds application in steel factories, marine equipment, ceramic factories, and die casting machinery-environments where continuous duty, high pressure, and long service intervals are non-negotiable requirements.

For more information on the A4VSO40 hydraulic pump, please visit https://www.baolilaihydraulic.com/product/.

Specifications

Selection Table

Q1:How often do axial piston pumps like the A4VSO40 need rebuilding?

A1: Service life depends heavily on fluid cleanliness and duty cycle. In well-maintained systems with clean fluid at ISO 16/14/11 or better, service lives exceeding 20,000 hours are achievable. Contaminated systems or frequent high-pressure shock loading can reduce this drastically. When volumetric efficiency drops below approximately 85–90% of new, internal wear inspection and potential valve plate/cylinder block replacement should be considered.

Q2:Is the A4VSO40 suitable for variable-speed drive (VFD) applications?

A2:Yes. The A4VSO is explicitly suited for variable-speed drives. Pairing a VFD-controlled motor with the A4VSO40's variable displacement creates a two-axis efficiency optimization — speed and displacement can both be modulated to minimize power consumption at partial load. This is increasingly common in new machine installations targeting energy efficiency certifications.

Q3:What is the price and delivery time of the A4VSO40 hydraulic pump?

A3:The specific price and delivery time will be provided based on the specific model you provide.

Q4:How to purchase an A4VSO40 hydraulic pump?

A4:You can visit https://www.baolilaihydraulic.com/contact/ to contact us and purchase our products through various methods.