Bosch Rexroth AA7VO355 axial piston variable pump

The AA7VO355 is a variable-displacement, open-circuit axial piston pump from Bosch Rexroth's A7VO product line. The "355" refers to its geometric displacement of roughly 355 cm³ per revolution at maximum swivel angle — placing it in the larger end of the series, which typically spans from around 28 cc/rev up to 500 cc/rev.

How the AA7VO355 Works

At its core, the pump converts rotational mechanical energy from a prime mover — a diesel engine, electric motor, or another pump in a through-drive train — into hydraulic flow, with the added ability to change that flow on demand without changing shaft speed.

The Bent-Axis Rotary Group

Inside the housing, a cylinder block containing the pistons rotates around an axis set at an angle to the drive shaft. As the block turns, each piston is drawn out and pushed back in through one full revolution, drawing fluid in on one side (suction) and expelling it under pressure on the other (discharge). Tilting the cylinder block angle — the "swivel angle" — changes the piston stroke length, which changes displacement per revolution and therefore output flow, all while the shaft keeps spinning at the same speed.

Variable Displacement in Practice

Because flow is proportional to both speed and displacement, the AA7VO355 can:

- Deliver maximum flow when the swivel angle is at its largest setting (Vg max)

- Reduce flow smoothly down toward zero (Vg min) as the swivel angle decreases

- Respond automatically to pressure, power, or flow-control signals depending on which control module is fitted

This is the whole point of a variable pump: instead of throttling excess flow across a relief valve (wasting energy as heat, as a fixed-displacement pump forces you to do), the pump only produces the flow the system actually needs at that instant.

Typical Applications

The AA7VO355's combination of high displacement, high-pressure capability, and rugged bent-axis construction makes it a natural fit for:

Mobile Hydraulics

- Concrete pump trucks, where high flow at high pressure is needed to push concrete through long boom sections

- Truck-mounted cranes and winches

- Large excavators and material handlers running through-drive pump combinations

 Industrial Hydraulics

- Plastic injection molding machines, where precise, variable flow control affects part quality and cycle time

- Rolling mills and metallurgical equipment, tolerating continuous high-pressure duty

- Presses and forging equipment

- Marine deck machinery — windlasses, mooring winches, cargo handling systems

Installation and Maintenance Considerations

A few practical points that come up repeatedly in the field:

Mounting Position Matters

Rexroth's documentation for the A7VO series specifies recommended installation orientations to ensure the case remains flooded with fluid at all times — running the pump dry, even briefly at startup, is one of the fastest ways to damage the bearings and rotary group.

Fluid Cleanliness and Viscosity

Bent-axis piston pumps operate with tight internal clearances at high pressure. Contamination control (per the fluid cleanliness class specified in Rexroth's datasheets) and staying within the recommended viscosity range at operating temperature are non-negotiable for achieving expected service life.

Case Drain Temperature

Because case drain temperature is influenced by both pressure and running speed, it's normal — and expected — for it to run hotter than tank temperature. Maintenance teams should monitor it against the pump's rated maximum rather than assuming tank temperature alone tells the full story.

Through-Drive Combinations

The A7VO series supports through-drive shafts, allowing an AA7VO355 to power a second (or third) pump off the same input shaft. Rexroth generally recommends limiting combinations to a small number of stacked units and checking permissible total input torque carefully — exceeding it risks shaft or coupling failure.

For more information on the AA7VO355 hydraulic pump, please visit https://www.baolilaihydraulic.com/product/.

Specifications

Selection Table

Q1: What control options are available on the AA7VO355?

A1: Typical options include pressure control (DR), power control (LR), load-sensing control (LS), and electric proportional control (EP), along with combined variants. The exact options depend on the specific ordering code.

Q2: What kind of applications typically use this pump?

A2: High-flow, high-pressure open-circuit systems: concrete pump trucks, cranes, presses, injection molding machines, rolling mills, and marine deck equipment are common examples.

Q3: How to purchase an AA7VO355 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 AA7VO355 hydraulic pump?

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