Bosch Rexroth A4VSO variable hydraulic pump for the Caterpillar Engineering Equipment 1773931 364-8329 368-0616 373-0689 437-016102 467-9658-00

The A4VSO is a variable-displacement axial piston pump with a swashplate design, made for open hydraulic circuits. The pump draws oil from a reservoir, and the swashplate angle determines how much oil it delivers per revolution. A bigger angle gives more flow; a smaller angle gives less. At zero angle, the pump essentially idles with minimal power draw.

Key characteristics

Design: Axial piston, swashplate, variable displacement

Circuit type: Open circuit

Nominal pressure: Typically 350 bar (about 5,100 psi), with higher peak pressure ratings

Size range: A broad series, from compact frame sizes up to very large displacements of roughly 1,000 cm³/rev

Drive options: Through-drive versions let you stack a second pump on the same shaft

Typical fluids: Mineral oil (HLP), plus certain fire-resistant and biodegradable fluids depending on the model

How the A4VSO Works

The swashplate principle

Inside the rotating group, pistons sit in a cylinder barrel and ride against a tilting swashplate. As the barrel turns, each piston strokes in and out. Tilt the plate and the stroke length changes, which changes displacement. Because the control adjusts displacement rather than dumping excess oil over a relief valve, the pump delivers only what the system demands.

Why that matters for energy use

A fixed-displacement pump pushes full flow all the time and wastes the surplus as heat. A variable pump like the A4VSO cuts that waste. On duty cycles with long holding phases, such as clamping, pressing, or hoisting, the energy savings can be substantial, and lower heat means longer oil and seal life.

A4VSO Control Options Explained

The control type is the most important choice after size. Common options include:

Pressure control (DR)

Holds a set system pressure and reduces flow as the load rises. It suits systems that need constant pressure with minimal power loss.

Pressure and flow control (DFR)

Adds flow regulation on top of pressure control, which gives you load-sensing-style behavior. It's useful when multiple actuators demand different flows.

Hydraulic displacement control (HD)

Sets displacement through an external pilot pressure. It works well when you need proportional, remotely commanded flow.

Electro-proportional control (EO / EP-type options)

Adjusts displacement using an electrical signal from a PLC or machine controller. Choose it when integrating with modern engine and equipment control systems.

Where the A4VSO Fits in Caterpillar-Related Applications

1. Auxiliary and power-unit hydraulics

Hydraulic power units (HPUs) driven by electric motors or Cat engines often use A4VSO pumps for continuous high-pressure duty.

2. Marine and offshore systems

Cat marine engines power vessels and platforms where winches, steering, and deck equipment need dependable variable-flow hydraulics.

3. Test and validation equipment

Engine and component test cells need accurate pressure and flow, which the A4VSO's control range handles well.

4. Industrial plants using Cat power generation

Facilities running Cat generator sets may use A4VSO-equipped systems for presses, material handling, and process machinery.

5. Replacement and cross-reference scenarios

If a machine was upgraded or retrofitted with a Rexroth pump, you'll need the Rexroth type code and serial number, not just the machine model.

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

Q1: Can I use an A4VSO in a closed-loop system?

A1: No. The A4VSO is designed for open circuits. Rexroth's A4VG series is the closed-circuit alternative.

Q2: Where do I find the type code?

A2: On the pump nameplate. Photograph it before ordering parts or a replacement.

Q3:What is the price and delivery time of the A4VSO hydraulic pump for the Caterpillar Engineering Equipment?

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

Q4:How to purchase an A4VSO  hydraulic pump for the Caterpillar Engineering Equipment?

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