How Variable Displacement Works

The pump’s efficiency comes from matching flow to demand by adjusting the swashplate angle:

• Full stroke (max flow) – steepest angle gives longest piston stroke, delivering the full 72 cc/rev for fast actuator motion.

• Modulated stroke – as demand drops, a hydraulic piston reduces the angle, shortening stroke and proportionally cutting output.

• Near‑zero stroke (standby) – angle nearly flat, pump only supplies enough flow to hold pressure and cover internal leakage. This “de‑stroked” mode drastically cuts power use and heat generation.

This robust mechanical principle, combined with Rexroth’s control valves, turns the A10VO72 into an adaptive, system‑aware power source.

Specifications & Model Code

The model name tells you key facts:

• A10VO – variable axial‑piston pump for open circuits.

• 72 – nominal displacement per revolution.

Key ratings:

• Displacement: 72 cc/rev

• Continuous pressure: 350 bar; peak: 400 bar

• Speed: compatible with electric motors and diesel engines

• Mounting: standard SAE or ISO flanges for easy replacement.

Control Options – Tailor the Pump to the Job

Swap the regulator to match your application:

• Pressure compensator (DB/DBU) – reduces displacement to maintain a preset pressure, cutting loss and heat during idle. DBU adds load‑sensing override for remote adjustment.

• Load sensing (LR/LRD) – constantly adjusts flow to keep a fixed pressure margin above the highest load, eliminating throttling losses – the most efficient option.

• Constant flow (FRC) – keeps output flow steady regardless of pressure changes; used for conveyors or feed drives needing consistent motor speed.

• Torque limiter (M/MR) – caps input power to protect the engine or motor from overload – essential for power‑limited installations.

Application Example – Injection Moulding Cycle

1. Clamp close – high flow needed: pump runs near full displacement.

2. Injection & holding – flow drops, pressure peaks: pressure compensator instantly reduces displacement, maintaining high force with minimal flow – saving over 80% energy during this long phase.

3. Ejection & return – moderate flow: pump smoothly increases displacement for controlled movement.

Key Advantages

• Energy savings – no fixed‑flow waste or relief‑valve losses, cutting running costs and emissions.

• Less cooling – reduced fluid throttling lowers heat load, extending component and oil life.

• Precise control – smooth, responsive metering for better process quality.

• Compact power – high output in a small, rugged package.

• Quiet operation – optimised porting reduces noise levels.

Typical Applications

• Plastics: injection moulding, extrusion, blow moulding.

• Metalworking: presses, shears, rolling mills.

• Mobile: cranes, aerial platforms, material handlers.

• Automation: test rigs, simulators, heavy‑duty systems.

• General industry: balers, compactors, any variable‑power need.

Maintenance & Troubleshooting

Preventive care:

• Fluid cleanliness – maintain ISO 4406 18/16/13 or better; particles are the main cause of wear.

• Viscosity – keep within 16‑36 mm²/s using high‑quality anti‑wear oil; wrong viscosity causes wear or cavitation.

• Inlet condition – ensure flooded suction with positive pressure; use correctly sized lines and filters to avoid cavitation (sharp rattling noise).

Common faults:

• Low output / weak power – worn internals, seal leak, or misadjusted control.

• Excessive noise – check clogged strainer, restricted inlet, cold oil, or air leaks (aerated oil sounds rough; cavitation is metallic rattling).

• Overheating – often due to continuous high‑pressure running at large displacement – check control setting, relief valve, or internal wear.

• Sluggish response – usually contamination in control orifices, sticking piston, or low pilot pressure.