Rexroth A28VLO280 axial piston variable double hydrauilc pump

The A28VLO280 is a swashplate-design axial piston pump with two rotary groups mounted on a common drive shaft, each feeding its own pressure port from a shared suction line. In plain terms: it's really two pumps in one housing, driven together but capable of delivering flow independently to two separate hydraulic circuits.

How the A28VLO280 Works

Swashplate Variable Displacement

Each rotary group contains a cylinder barrel with pistons arranged parallel to the drive shaft. The pistons ride against a swashplate set at an angle. As the shaft turns, the pistons reciprocate in and out of the barrel bores, drawing in fluid on one stroke and pushing it out under pressure on the other.

Because the swashplate angle is adjustable, the pump's displacement — and therefore its output flow — can be changed without changing shaft speed. Tilt the swashplate further, and each piston stroke gets longer, pushing more oil per revolution. Bring it back toward neutral, and flow drops toward zero even while the engine or motor keeps running at full speed.

Two Independent Circuits, One Drive

The "double pump" part matters for machine design. Instead of running two separate pumps off a splitter gearbox, the A28VLO280 packages both rotary groups in-line. This:

Saves mounting space and weight on the prime mover

Reduces the number of shaft seals and coupling points

Allows each section to be sized and controlled differently for its own circuit (for example, one side feeding a steering/implement circuit, the other feeding a working hydraulic circuit)

Self-Priming or Charge-Pump Assisted

Like most pumps in this class, the A28VLO280 can operate self-priming for lighter-duty applications or be paired with a charge pump for applications where inlet conditions are marginal — long suction lines, high-speed operation, or cold-start viscosity concerns.

Where the A28VLO280 Is Used

This pump class is aimed squarely at mobile machines with multi-circuit hydraulic demands — situations where one prime mover has to power more than one hydraulic function with different pressure and flow needs.

Example 1: Mobile Crane Hydraulics

On a mobile crane, one section of the double pump might supply the slewing and outrigger circuit while the other handles the main hoist or telescoping boom circuit. Independent swashplate control means the operator can run slow, precise slewing movements at the same time as a high-flow hoisting operation, without one circuit starving the other.

Example 2: Construction and Earthmoving Equipment

In graders, loaders, or specialized construction machines, a double pump configuration lets the steering and implement circuits draw from separate flow sources. This isolates a steering fault from implement performance (and vice versa) — a meaningful safety consideration.

Example 3: Industrial Multi-Circuit Systems

Outside mobile equipment, stationary industrial applications with two independent process circuits — such as press systems or material handling lines — use the same double-pump logic to avoid running two full pump-and-motor assemblies.

Installation and Maintenance Notes

A few practical points that experienced hydraulic technicians tend to flag with this pump family:

Match the control type to the machine's control philosophy. These pumps ship with different regulator/control options (pressure control, load-sensing, power control, electric proportional, etc.). Swapping in a pump with the wrong control variant will make the machine behave unpredictably even if the mechanical size is correct.

Check shaft and coupling alignment carefully. Because this is a tandem/double unit, the shaft carries torque through both rotary groups — misalignment stresses show up faster than on a single pump.

Don't skip fluid cleanliness targets. Axial piston pumps run tight piston-to-bore clearances; contamination is the single most common cause of premature wear in this pump class.

Verify the full part number before ordering a replacement. As noted above, the same base designation can correspond to several different configurations (control type, shaft end, mounting flange, rotation direction, seal material).

Inspect case drain flow during service. A rising case drain flow rate over time is typically the earliest sign of internal wear in a swashplate pump.

For more information on the A28VLO280 hydraulic pump, please visit https://www.baolilaihydraulic.com/product/.

Specifications

Selection Table

Q1: What does "variable double pump" mean on the A28VLO280?

A1: It means the unit contains two independently adjustable pumping sections on one shaft, each able to change its own flow output by adjusting its swashplate angle — effectively giving a machine two independently controllable hydraulic supplies from one drive point.

Q2: How do I identify the right replacement pump?

A2: Match the complete alphanumeric ordering code and, where available, the Rexroth material number (the "R9…" code) rather than relying on the short model name alone — control type, shaft, flange, and rotation direction all affect fit and function.

Q3: How to purchase an A28VLO280 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 A28VLO280 hydraulic pump?

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