Bosch Rexroth A4VG28 axial piston hydraulic pump

The Bosch Rexroth A4VG28 is more than just a pump; it's a variable displacement axial piston unit designed for high-performance closed-loop hydraulic systems. For applications demanding extreme reliability, dynamic control, and operational efficiency, the A4VG28 is a perfect fit. Rated at 28 cubic centimeters per revolution, this model sets the standard in mobile and industrial machinery—from small excavators to complex material handling systems, it skillfully transforms mechanical input into precisely regulated hydraulic power with extremely high energy density.

Displacement, Pressure, and Performance Range

The "28" in A4VG28 represents its rated displacement of 28 cubic centimeters per revolution, making it ideal for medium-power, high-response applications. Designed for durability, this model reliably delivers continuous operating pressures up to 350 bar (≈5,075 psi) and even higher peak pressures under transient loads. This robust pressure capability ensures system integrity and provides critical safety margins for demanding operating cycles, directly reducing total cost of ownership. Swashplate Principle: The Heart of a Variable Displacement Pump

The revolutionary performance of the A4VG28 stems from its axial piston, variable-angle swashplate design—a hallmark of Rexroth's engineering excellence.

• Basic Mechanical Principle: Multiple pistons are arranged axially around a rotating cylinder. These pistons rest against an inclined swashplate. The rotation of the shaft translates into the reciprocating motion of the pistons, generating pumping action.

• Key to High Efficiency: The swashplate angle is dynamically adjustable. Changing this angle alters the piston stroke, directly and proportionally changing the pump's displacement and output flow rate—from zero to maximum—while the input shaft speed remains constant. This on-demand flow control is the fundamental technology for eliminating throttling losses, minimizing heat generation, and significantly saving energy.

Intelligent Control: Pump Perfectly Matched to Application

The true versatility of the A4VG28 stems from its adaptable control system. The pump acts as the power source, while the selected control system acts as the brain, adjusting performance according to specific operational needs.

Main Control Methods:

• HD (Hydrostatic) Control: A pressure-compensated pure hydraulic control. It automatically reduces displacement when the system pressure approaches a preset limit, providing a powerful pump-integrated pressure relief function. It is ideal for simple, durable, and pressure-limiting applications in drive systems.

• EP (Electro-Proportional) Control: This system uses precise electronic commands. Electrical input signals (e.g., 0-10V or 4-20mA) directly control the swashplate angle proportionally via a proportional solenoid valve. This allows for seamless speed and flow regulation via joystick or PLC, resulting in intuitive machine operation.

• EW (Electro-Proportional Load Sensing) Control: EW control combines proportional flow control with load sensing (LS) logic for peak efficiency. The pump automatically provides the flow required by the actuator, with pressure slightly higher than the pressure caused by the load. This on-demand matching operation significantly reduces energy consumption, cooling requirements, and operating costs for complex, multi-functional machinery.

Application Case: Efficiency Improvement in Forestry Cranes

In modern forestry cranes, the A4VG28 pump equipped with EW load-sensing control is crucial. Whether performing delicate positioning operations or high-power lifting work, this pump adapts instantly. It provides the precise flow required for smooth, accurate movement, avoiding waste and directly reducing fuel consumption and the thermal load on the vehicle's engine. Ultimately, this results in higher productivity, longer component life, and a smaller environmental impact.

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Specifications

Selection Table

Q1: What is the primary application difference between the A4VG28 and a fixed-displacement pump?

A1:The A4VG28 is a variable-displacementpump. It is the core component for closed-loop, hydrostatic drive systems (e.g., for travel drives) or sophisticated open-loop work hydraulics requiring variable flow. A fixed-displacement pump provides constant flow, which must then be throttled or bypassed, often wasting energy. The A4VG28 adjusts its output to match demand, saving energy and reducing heat.

Q2:What is the most critical maintenance aspect for ensuring long service life?

A2: Beyond adhering to recommended oil change intervals, filtration is paramount.​ Maintaining fluid cleanliness to ISO 4406 19/17/14 or better (NAS 1638 Class 8) is non-negotiable. The pump's high-precision components, with tight tolerances, are highly susceptible to wear from particulate contamination. Investing in a high-quality filtration system protects your investment in the pump.

Q3:How to purchase an A4VG28 hydraulic pump?

A3:You can click on the right sidebar or the contact information in the top bar to contact us to purchase. You can do so via email, form, WeChat, WhatsApp, or other methods.

Q4:What is the price and delivery time of the A4VG28 hydraulic pump?

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