A4VSO Series Axial Piston Variable Pump (Model: APA4VSO250LR2DY/30R-VZB25U35-SO757, Part No.: R902555191)
The A4VSO series is a high-performance axial piston variable pump designed for closed-circuit hydrostatic drive systems, with the APA4VSO250LR2DY/30R-VZB25U35-SO757 (part number R902555191) as a heavy-duty variant. It delivers adjustable flow proportional to drive speed and displacement, offering exceptional pressure resistance and precise control for high-power hydraulic applications. Available in a wide displacement range—including A4VSO71, A4VSO125, A4VSO180, A4VSO250, A4VSO355, A4VSO500, and A4VSO750—it adapts to diverse flow and power demands across industrial and mobile scenarios.
Core Design & Performance Highlights
Features a robust bent-axis design and axial piston configuration, ensuring high rigidity, strong load-bearing capacity, and extended service life even under continuous heavy-duty operation.
Boasts impressive pressure ratings: rated working pressure up to 35 MPa (5075 psi) and peak pressure reaching 40 MPa (5800 psi), supporting high-power system output without compromising stability.
High volumetric efficiency (up to 95%) and mechanical efficiency, minimizing energy loss and heat generation for cost-effective and reliable operation.
The LR2DY/30R-VZB25U35-SO757 variant integrates load-sensing and pressure control, optimizing oil supply based on real-time system demands.
Key Control & Functional Traits
Load-Sensing Control (LR): Automatically adjusts displacement to match actual load requirements, reducing energy waste and improving system responsiveness.
Pressure Compensation (VZB): Maintains stable system pressure under fluctuating loads, preventing pressure spikes and protecting downstream components.
Dual-Displacement (DY) Option: Switches between two displacement settings to balance high power and energy efficiency for multi-condition operations.
Compatibility with Series Standards: Shares modular core components with other A4VSO models, simplifying maintenance, replacement, and spare parts management.
Application Range
Ideal for high-power closed-circuit hydraulic systems, it is widely used in heavy construction machinery (mining excavators, large cranes, concrete pump trucks, wheel loaders), industrial equipment (steel mill rolling machines, hydraulic presses, plastic injection molding machines), and marine systems (ship propulsion, offshore equipment). It provides stable power for traction, lifting, slewing, and pressing operations, adapting to harsh working environments with heavy loads and frequent load changes.
Core Advantages
Wide Displacement Coverage: From 71 cc/rev (A4VSO71) to 750 cc/rev (A4VSO750), meeting small to ultra-high power system requirements.
Durable Construction: Resists wear, corrosion, and cavitation, with a robust housing and high-quality seals suitable for extreme temperatures and dusty/humid conditions.
Flexible Installation: Compatible with SAE/metric mounting flanges and multiple port configurations, supporting horizontal and vertical installation for space-constrained setups.
Easy Maintenance: Modular design allows quick access to key components (pistons, bearings, seals), reducing downtime for inspections and repairs.
