Rexroth A15VLO open circuit variable displacement hydraulic pump

The A15VLO is a swashplate-design axial piston pump built by Bosch Rexroth for open-circuit hydrostatic drives.

How the A15VLO Actually Works

Axial Piston, Swashplate Architecture

Inside the housing, a cylinder barrel containing multiple pistons rotates with the drive shaft. As the barrel turns, each piston rides against an angled swashplate. That angle forces the pistons to move back and forth within their bores — drawing fluid in on one side and expelling it under pressure on the other. Tilt the swashplate further, and each piston stroke gets longer, increasing displacement per revolution. Bring the swashplate toward zero angle, and displacement (and flow) drops toward zero, even while the shaft keeps turning.

This is the mechanical heart of nearly every Rexroth "V" series piston pump, and it's what makes variable displacement possible without changing pump speed.

The Role of the Integrated Charge Pump

The defining feature of the A15VLO is its built-in charge (feed) pump, typically a centrifugal-type impeller mounted at the rear of the unit. Its job is to pre-pressurize the main pump's suction side. This matters for a few practical reasons:

Reliable filling at higher speeds. A self-priming pump (like the A15VSO) can struggle to fill its pistons completely at high shaft speeds, leading to cavitation. The charge pump solves this by supplying fluid under slight positive pressure.

Easier cold starts. In cold conditions, hydraulic fluid gets thick and doesn't want to flow. A charge pump helps overcome that viscosity resistance during startup.

No external boost needed. Because the charge pump handles inlet pressurization internally, you typically don't need to pressurize the reservoir or add an external boost pump — simplifying the overall system design.

If your application involves high shaft speeds, cold ambient starts, or long suction lines, the A15VLO's charge pump is often the deciding factor over the simpler A15VSO.

Control and Regulation Options

One of the reasons this pump family has stayed relevant for decades is its extensive menu of control devices. Depending on the ordering code, an A15VLO can be configured with:

Pressure controllers (DR) — hold system pressure constant by reducing displacement as pressure approaches setpoint

Power controllers (LR) — limit the drive power the pump can absorb, protecting the prime mover

Load-sensing controllers (LS) — match pump output to actual downstream demand for energy efficiency

Electric proportional controls — allow remote or PLC-based control of displacement via proportional solenoids

Combination controllers — stack two or more of the above (e.g., pressure + power) for more sophisticated behavior

This modularity is a major reason system designers reach for this pump instead of a fixed-displacement alternative: you can tune the exact control behavior to the machine rather than working around a one-size-fits-all pump.

Common Applications

Because it was designed for stationary industrial drives rather than mobile equipment, you'll typically find the A15VLO in:

Plastic injection molding machines — where load-sensing or variable-pressure control minimizes energy use across the molding cycle

Machine tools and presses — where consistent pressure and fine displacement control matter for process repeatability

Steel and metal processing lines — running continuously at higher shaft speeds where the charge pump's cavitation protection pays off

Test rigs and simulation equipment — where precise, programmable flow behavior is required

General industrial power units — anywhere a stationary electric motor drives a hydraulic system that needs variable flow

For more information on the A15VLO hydraulic pump, please visit https://www.baolilaihydraulic.com/product/.

Specifications

Selection Table

Q1: Is the A15VLO suitable for mobile equipment?

A1: No. It's designed and rated for stationary, industrial applications. Rexroth's mobile-duty equivalents are pumps like the A4VG (closed circuit) or A11VO/A11VLO variable pumps built for on-highway and off-highway vehicles.

Q2: Does the charge pump require its own external plumbing?

A2: Generally no — the charge pump draws from the same reservoir/suction line as the main pump and is self-contained within the unit, which is part of what simplifies system design compared to adding an external boost pump.

Q3: How to purchase an A15VLO hydraulic pump?

A3: You can visit https://www.baolilaihydraulic.com/contact/ to contact us and purchase our products through various methods.

Q4: What is the price and delivery time of the A15VLO hydraulic pump?

A4:The specific price and delivery time will be provided based on the specific model you provide.