A4VG Series Pump with DA Valve (A4VG系列带DA阀泵)
1. Product Overview
• Series Introduction: The A4VG series is a variable axial piston pump developed by Bosch Rexroth, widely used in closed-circuit hydrostatic transmission systems.
• DA Valve Function: The DA (Drain Adjustment) valve is an integrated control valve that regulates the pump's displacement based on engine speed, ensuring optimal power matching and preventing engine overload.
2. Technical Specifications
• Displacement Range: 28–250 cm³/rev (multiple sizes available: 28, 40, 56, 71, 90, 125, 180, 250).
• Maximum Pressure: 400 bar (continuous), 450 bar (peak).
• Control Modes: Supports various control forms (e.g., HW, EP, HD, DA) to adapt to different application needs.
• DA Valve Characteristics:
• Generates a pilot pressure proportional to the pump's drive speed.
• Adjusts the pump's swashplate angle via a 3/4-way solenoid valve, controlling flow and pressure.
• Prevents engine stall by reducing pump displacement when engine speed drops.
3. Key Features
• Closed-Circuit Design: Eliminates the need for an external charge pump, simplifying the hydraulic system.
• High Power Density: Compact structure with integrated control functions (e.g., pressure relief valves, check valves).
• Energy Efficiency: The DA valve optimizes power distribution by matching pump output to engine load, reducing fuel consumption.
• Low Noise Operation: Patented noise-reduction technology ensures quiet performance.
• Robust Construction: High-quality main bearings and hydraulic balancing system extend service life.
4. Applications
• Construction Machinery: Excavators, concrete pumps, and hydraulic cranes.
• Mining Equipment: Coal haulers, shearers, and drum rollers.
• Industrial Machinery: Hydraulic power units and presses.
5. Working Principle
• DA Valve Operation:
• Detects changes in engine speed and adjusts the pilot pressure accordingly.
• The pilot pressure acts on a variable piston, which tilts the swashplate to change the pump's displacement.
• This ensures the pump's torque matches the engine's output torque, preventing overload.
• System Protection:
• The DA valve reduces pump displacement when engine speed drops, safeguarding against engine stall.
• Built-in safety and pressure cut-off valves protect the hydraulic system from overpressure.
6. Advantages
• Automatic Power Distribution: The DA valve enables seamless power matching between the engine and hydraulic system.
• Enhanced System Reliability: Reduces the risk of engine damage due to hydraulic overload.
• Improved Fuel Efficiency: Optimizes pump performance to minimize energy waste.
• Versatile Control Options: Supports multiple control modes for flexible system integration.
7. Maintenance & Troubleshooting
• Regular Checks: Monitor pilot pressure, pump displacement, and engine speed to ensure proper DA valve operation.
• Common Issues:
• Pilot Pressure Fluctuations: May indicate a faulty DA valve or solenoid.
• Pump Displacement Irregularities: Could be caused by mechanical wear or control signal issues.
• Recommended Actions:
• Follow manufacturer guidelines for pump installation, commissioning, and maintenance.
• Use high-quality hydraulic oil and filters to prevent contamination.
8. Model Examples
• A4VG56DA1D8:
• Displacement: 56 cm³/rev.
• DA control for engine speed-dependent displacement adjustment.
• A4VG125EP2D1/32R:
• Displacement: 125 cm³/rev.
• EP (electro-proportional) control with additional features for precise flow regulation.
The A4VG series pump with a DA valve is a high-performance hydraulic component designed for demanding applications. Its integrated DA control ensures efficient power management, enhancing system reliability and reducing operational costs.
