Rexroth A20VO variable double hydraulic pump for the Caterpillar crawler excavator 295-9676-02 369-9676-03 284-9631-03 325-9799-02 373-0644 194-0436-03

The A20VO is a variable displacement axial piston pump built as a "double" or "tandem" unit — two independent axial piston rotary groups, each in a swashplate design, mounted back-to-back on a single housing and driven off one shaft. Bosch Rexroth designed it for open-circuit hydrostatic drives, and it borrows proven internal components from the company's A11VO, A10VO, and A4VSO pump families, which is part of why it has earned a reputation for durability in rough mobile equipment duty cycles.

The "double pump" configuration is the key design idea. Instead of running two separate single pumps off a splitter gearbox — extra weight, extra seals, extra failure points — Rexroth packages two variable pumps in one housing. Each half can be sized differently and controlled independently, which is exactly what an excavator needs: one section can feed the boom/arm/bucket circuit while the other feeds swing and travel, or the two sections can be summed together for high-flow operations like fast digging cycles.

Why Caterpillar Uses This Architecture

Caterpillar's mid-to-large crawler excavators (many machines in the 320 through 390 size classes, among others) rely on split-flow, load-sensing hydraulic systems. A single fixed-displacement pump can't give an operator the fine, simultaneous control needed to curl the bucket while swinging the house and creeping forward on tracks — you'd either waste huge amounts of energy through relief valves or starve one function whenever another is active. A variable double pump like the A20VO solves this by matching flow to demand on each side of the circuit independently, then summing flow through the valve stack when the operator calls for combined movements.

How the A20VO Works Inside the Excavator's Hydraulic System

Load-Sensing and Flow Matching

Most Cat excavators equipped with an A20VO-type pump use a load-sensing control. A small pilot signal, taken from the highest-pressure work function currently active, tells the pump's regulator how much flow the system actually needs at that instant. The swashplate angle adjusts continuously to supply exactly that flow — no more, no less. This is what gives modern excavators their smooth, almost telepathic response: touch the joystick lightly, and the pump barely strokes; slam it, and the swashplate swings toward maximum displacement almost instantly.

Power (Torque) Control

Because engine horsepower is finite, the A20VO's power control function prevents the two pump sections from demanding more torque than the diesel engine can supply. As system pressure rises, the controller reduces displacement to hold total power draw within a set limit — this is why an excavator won't stall the engine even when both track motors, the swing motor, and the boom cylinder are all working against high resistance simultaneously.

Maintenance Best Practices

Fluid Cleanliness Comes First

Axial piston pumps run extremely tight tolerances between the piston shoes, swashplate, and cylinder block. Contaminated hydraulic oil is, by a wide margin, the leading cause of premature A20VO failure in the field. Cat recommends filtration to ISO cleanliness targets appropriate for the machine's proportional and servo valves — typically far cleaner than what a simple return-line filter alone can guarantee.

Watch Case Drain Flow and Temperature

The pump's case drain line carries internal leakage back to the tank. A sudden increase in case drain flow, or oil that runs noticeably hotter than the rest of the system, is often the earliest sign of internal wear before performance loss becomes obvious to the operator.

Respect the Through-Drive Load Limits

Because many Cat installations use the A20VO's through-drive to power a pilot pump or fan-drive pump, it's worth confirming that the auxiliary pump's torque draw stays within the rated limit for that shaft. Overloading the through-drive shortens bearing life on the main unit as well.

Follow OEM Torque and Alignment Specs on Reinstallation

Whether swapping in a remanufactured unit or reinstalling after service, shaft misalignment with the engine or pump drive housing is a common, avoidable cause of premature seal and bearing failure. Dowel pins, coupling alignment, and mounting bolt torque sequences should follow Caterpillar's service literature for the specific model.

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Q1: What excavator sizes typically use the A20VO pump?

A1: The A20VO family covers a wide displacement range, so different frame sizes within it are matched to different excavator classes — smaller displacement sizes suit mid-size crawler excavators, while the larger sizes serve heavier machines with higher horsepower engines and larger cylinder bores.

Q2: Can I identify my exact A20VO variant from the pump nameplate?

A2: Yes. The nameplate carries Rexroth's full ordering code, which specifies displacement size, control type (pressure cutoff, load sensing, power control, EP), rotation direction, and shaft configuration. Cross-referencing that code against Rexroth's RE 93100 datasheet, or your Caterpillar parts catalog, gives you the exact specification.

Q3:What is the price and delivery time of the Rexroth A20VO pump for the Caterpillar crawler excavator?

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

Q4: How to purchase an A20VO hydraulic pump for the Caterpillar crawler excavator?

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