A11VO series

First, General Product Overview

The A11VO series is a high-pressure variable-displacement piston pump developed by Bosch Rexroth of Germany specifically for open hydraulic circuits in mobile machinery. Featuring a swashplate variable-displacement design, the series offers eight standard displacement sizes (40/60/75/95/130/145/190/260) and is designated as Series 10. It is one of the most widely used main hydraulic pumps in the construction machinery market.

1. Distinction Between the Two Basic Models

A11VO: The standard base model, without a built-in centrifugal makeup pump, relies on self-priming for oil supply; suitable for direct use in conventional operating conditions for small-to-medium displacements (40–145), featuring a simple structure and lower cost.

A11VLO: An extended derivative model, with a built-in impeller-type makeup pump in the pump body, providing forced suction, cavitation resistance, and improved cold start performance; Mandatory for high-displacement, heavy-duty equipment (190, 260), significantly improving stability under high-speed and low-temperature operating conditions [(Rexroth St...)].

2. Core Common Features of the Series

High Pressure and Heavy Duty: Rated continuous operating pressure of 350 bar (35 MPa) and short-term peak pressure of 400 bar (40 MPa), suitable for continuous high-pressure loads in heavy-duty equipment;

Infinitely Variable: Continuous adjustment of swashplate angle from 0° to maximum, with displacement varying infinitely from 0 to the rated value; flow is delivered on demand, significantly reducing energy loss through overflow;

100% Through-Shaft Rear Drive: The pump’s output shaft can be connected in series with gear pumps or piston pumps of the same specification, allowing a single engine power source to drive multiple hydraulic systems simultaneously, thereby simplifying the vehicle’s hydraulic circuit layout;

Full Range of Control Modules: Comprehensive coverage of mechanical-hydraulic, pilot-operated hydraulic, and electro-proportional electronic control systems, suitable for both manual and fully automatic electronically controlled construction machinery;

Operationally Adjustable Constant Power: Models equipped with an LR constant-power valve body allow external adjustment of the power curve without stopping the equipment, enabling rapid matching to diesel engine horsepower and preventing stalling;

High efficiency and long service life: volumetric efficiency ≥94%, overall system efficiency over 90%, high-strength cast iron housing, and 9 sets of wear-resistant plunger-shoe pairs ensure durability in harsh construction site environments;

High installation versatility: standard SAE flanges and splined drive shafts support both left-hand and right-hand rotation, and can be installed in either horizontal or vertical orientations.

Second, Internal Structure and Operating Principle

Core Component Configuration

1. Drive Shaft Assembly: Connects to the engine’s power take-off (PTO) box to transmit torque and drive the cylinder block’s rotation; features standard SAE splines with extremely high coaxiality requirements.

2. Cylinder Block + 9 Sets of Piston-Slide Shoe Pairs: The core hydraulic power conversion components, where the slide shoes contact the swash plate’s surface; as the cylinder block rotates, the pistons reciprocate to perform oil intake, pressurization, and oil discharge.

3. Swashplate + Servo-Controlled Variable Piston: The servo piston pushes the swashplate to change its tilt angle; the greater the tilt angle, the higher the displacement and flow rate; when the tilt angle returns to zero, the output flow rate approaches 0.

4. Distribution Plate: A friction pair at the end face of the cylinder block that separates the low-pressure suction port from the high-pressure discharge port, isolating the high- and low-pressure fluids.

5. Top-Mounted Integrated Control Valve Block: A monoblock valve assembly integrating pressure, constant power, load-sensing, and proportional control spools, which determine the pump’s variable regulation logic.

6. Cast Iron Housing: Houses all internal components and features dedicated ports for the suction port (S), high-pressure discharge port (A), dual drain ports (T1/T2), LS load feedback port, and pilot control port (X).

7. Exclusive to the A11VLO: Built-in centrifugal replenishment impeller for low-pressure oil replenishment and cooling of friction pairs, eliminating cavitation noise at high speeds.

Basic Operating Principle: The drive shaft drives the cylinder block to rotate continuously, while the plunger follows the inclined plane of the swash plate to perform reciprocating linear motion:

1. Suction Stroke: The plunger extends outward, increasing the volume of the cylinder cavity; low-pressure fluid is drawn in through the suction port;

2. Pressurization stroke: The plunger retracts inward, reducing the chamber volume; the pressurized oil is then delivered to the hydraulic system through the high-pressure port;

The control system uses pilot oil pressure to drive the servo piston, adjusting the swashplate angle in real time to achieve stepless flow regulation. The pump delivers only the flow rate required by the load, eliminating excess overflow losses.

Elephant Fluid Power Technical team has many years of operation and service experience, Provide customers with professional hydraulic system solutions, Quality assurance of quality products, We have many years in A11VO series products.

Rexroth A11VO hydraulic pump

Rexroth A11VO