Key Design Characteristics

Two independent flows from a single drive input, each proportional to speed and displacement – available across the A20VG, A22VG, A24VG, and A30VG families. Infinitely variable displacement via swashplate angle adjustment, with smooth reversal through neutral meaning flow direction changes without harsh transitions. Integrated pressure relief valves (typically four) on the high-pressure side protect both pump and motor from overload, with boost pressure functionality where relief valves do double duty as boost valves. This is a pump family designed specifically for closed-loop hydrostatic transmissions – not general-purpose open-circuit fluid transfer. Rated pressures reach 380 bar nominal and 420 bar peak for the A22VG, while the A24VG delivers 450 bar nominal and up to 500 bar peak.

Representative Material Numbers

For the A20VG45, complete pump assembly Material No. R902192842 for A24VG045-045 variant.

For the A22VG045HT1003M1/40B-RNB2S73UB2S4A-Y, Material No. R902201465.

For the A22VG045HT1005M1/40B-RNB2S73FB2S4A-Y, Material No. R902211027.

For the A24VG085-085HP1HP1R0MM0/10MRC6T1B2S4B6-0, Material No. R902249797.

Spare part numbers for A24VG45 include Material Nos. R902157177, R902192734, R902192856, and R902157425.

Typical Applications

Excavators – separate circuits for travel drive and upper-structure slewing. Cranes – independent hoist, slew, and travel functions without cross-interference. Drilling rigs – simultaneous rotary and feed functions. Skid steer loaders – the A22VG045HT series is specifically engineered for these applications. Combine harvesters, road rollers, asphalt pavers, and self-propelled agricultural machines from brands including John Deere, Hamm, and Volvo. Other multi-function construction and mining equipment where two hydrostatic circuits need to run off one prime mover.

The practical benefit is efficiency and control precision. Because each circuit is independently variable, the operator gets smoother, more responsive control, and the engine doesn’t have to compromise between two competing hydraulic demands routed through a single variable unit.

The 50% Differentiation – Why Choose the A20VG/A22VG/A24VG/A30VG

Beyond the dual-circuit architecture, these pumps offer a through-drive capability – mount a secondary gear pump or another axial piston pump directly onto the rear, creating a multi-pump stack without an extra PTO. This saves space, weight, and installation cost, giving a 50% packaging advantage over single-pump layouts.

The asymmetric size combinations (e.g., 110-85 or 125-110) allow different displacements for each circuit – travel and slew drives rarely need identical flow. The on-board electronics (OBE) variant delivers software-based controls for up to 10% increase in travel drive effectiveness. Combine that with higher pressure ratings (up to 500 bar peak), smoother neutral transition, and the compact design with a common port plate for both rotary groups – and the A20VG/A22VG/A24VG/A30VG series delivers a clear performance edge for demanding mobile hydrostatic applications.

Choosing the Right Pump for Your Application

A few practical questions worth answering before specifying a size:

1. What are the independent flow demands of each circuit? Travel and slew drives rarely need identical displacement – that is exactly why the asymmetric size combinations (like 110-85 or 125-110) exist.

2. What is the realistic peak operating pressure, not just the theoretical maximum? Sizing a pump to run near its 500 bar ceiling constantly will cost you in service life and unplanned downtime.

3. Does the application benefit from on-board electronics? If engine downsizing, emissions reduction, or travel drive efficiency gains are priorities, the OBE variant deserves a serious look rather than defaulting to a purely mechanical control setup.

4. What fluid environment will the machine operate in? Standard mineral oil according to DIN 51524, environmentally acceptable fluid, or fire-resistant fluid – this decision affects seal compatibility and should be locked in before final pump selection.