Rexroth A4VG A4VTG closed-circuit hydraulic pump for the Liebherr wheel loader 10021818A 10470657 10470662 10814574 11320257 5717293 5717298

A4VG is a general-purpose, swashplate-design, variable-displacement axial piston pump for closed-circuit hydrostatic transmissions. It is common in wheel loaders, rollers, telehandlers, and sweepers.

A4VTG is a Rexroth variant developed mainly for truck-mixer drum drives, not wheel loader propulsion.

Practical advice: don't order from the machine model alone. Read the pump nameplate, note the full type code and serial number, and cross-check against Liebherr's parts documentation for your machine's serial range.

How a Closed-Circuit Hydrostatic Pump Works

Closed loop vs. open loop

In an open circuit, the pump draws oil from a tank and returns it there. In a closed circuit, oil flows in a loop between the pump and the travel motor. Reversing the swashplate angle reverses flow direction, which gives you forward and reverse without a directional valve and with excellent controllability.

The swashplate principle

Inside an A4VG, a rotating cylinder block carries pistons that slide against a tilting swashplate. The tilt angle sets displacement:

Zero angle: no flow (neutral)

Positive angle: flow to one side of the loop (forward)

Negative angle: flow to the other side (reverse)

Built-in charge pump and valves

The A4VG integrates several components that matter to technicians:

Charge (boost) pump: replaces leakage and keeps the low-pressure side supplied, preventing cavitation.

High-pressure relief valves with boost-check function: protect against pressure spikes and let charge oil into the low-pressure side.

Pressure cut-off: limits system pressure for protection.

Charge pressure relief valve: holds charge pressure at the specified level.

Common Applications

Compact and mid-size wheel loaders

Hydrostatic drive suits loading cycles with constant direction changes. Smooth inching, high tractive effort at low speed, and engine-braking behavior come naturally with a closed-circuit pump and motor pair.

Example 1: Sluggish forward travel under load

A contractor reports a loader that drives normally empty but loses pull climbing a stockpile. The technician measures charge pressure (healthy), then checks case drain flow and finds it far above spec. Internal wear is letting oil bypass, so the pump can't hold system pressure. The fix is a rebuild or a replacement rotating group, not a new relief valve.

Example 2: Machine creeping in neutral

An operator complains the loader drifts at rest. The cause may be a mis-set neutral position, a worn control valve, or a faulty electronic control signal. It rarely requires replacing the whole pump, so check the control and neutral adjustment first.

Example 3: Overheating hydraulic oil

A loader running a quarry shift runs hot. Contaminated oil, a clogged cooler, and a worn pump all produce excess heat. Check cooler airflow and filter condition before condemning the pump.

Maintenance Practices That Extend Pump Life

Keep the oil clean

Contamination is the leading killer of axial piston pumps. Rexroth specifies strict cleanliness classes for this pump family (check the datasheet; roughly ISO 4406 20/18/15 is a common target). Replace filters on schedule and use clean transfer equipment.

Respect viscosity and temperature

Hot oil thins, wear climbs, and efficiency drops. Use the recommended fluid grade and keep operating temperatures within the manufacturer's limits.

Check charge pressure routinely

Low charge pressure is an early warning of charge pump wear, a stuck relief valve, or a filter problem.

Monitor case drain flow

A rising case drain flow trend is one of the clearest indicators of internal wear. Record it at service intervals so you can see the trend.

Prime and flush correctly after any repair

Fill the pump housing with clean oil before startup, and run the machine at low speed and low load initially. Dry starts destroy pumps quickly.

For more brands and equipment models, please visit https://www.baolilaihydraulic.com/brand/

Q1: How long does an A4VG pump last?

A1: There's no single figure. Life depends heavily on oil cleanliness, temperature, load, and maintenance. Well-maintained pumps can run many thousands of hours.

Q2: Why does my loader lose power when hot?

A2: Hot oil is thinner, so internal leakage rises. Check cooler performance, oil condition, and case drain flow.

Q3: What is the price and delivery time of the A4VG/A4VTG hydraulic pump for the Liebherr wheel loader?

A3: The specific price and delivery time will depend on the equipment model or specific product model you provide.

Q4: How do I purchase an A4VG/A4VTG hydraulic pump for the Liebherr wheel loader?

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