I. Product Overview
TheA10VG28/45 seriesis a range of axial-piston variable-displacement pumps with inclined-axis design, developed by Bosch Rexroth for closed-circuit hydraulic systems. TheDA3R valveserves as the core control component of this series, regulating pump displacement, flow rate, and direction to meet dynamic operational demands across various applications.
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II. Functions and Features of the DA3R Valve
1. Dynamic Displacement Control
• The DA3R valve adjusts the pump’s swashplate angle in real-time via hydraulic or electrical signals, enabling stepless displacement modulation (0%–100%).
• Example: In excavator travel systems, the DA3R valve automatically regulates pump output flow based on load changes to ensure smooth operation.
2. Pressure Compensation
• Integrated with a pressure cut-off valve, the DA3R valve reduces pump displacement when system pressure reaches the preset limit, preventing overpressure damage.
• Typical Application: Vibratory systems in road rollers maintain constant vibration pressure while protecting hydraulic components.
3. Directional Control
• The DA3R valve switches the pump’s suction and discharge directions, enabling forward/reverse rotation or stopping of actuators.
• Example: In loader steering systems, the DA3R valve controls steering cylinder extension/retraction by altering pump flow direction.
4. Load-Sensing (LS) Control (Optional)
• Some DA3R valve variants support load-sensing functionality, dynamically matching pump output flow to load demands for reduced energy consumption.
• Application Scenario: Agricultural machinery (e.g., combine harvesters) require real-time adjustment of working device speeds based on crop height/density.
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III. Technical Specifications
• Displacement Range: A10VG28 (28 cm³/rev), A10VG45 (45 cm³/rev)
• Rated Pressure: 300 bar (peak pressure up to 350 bar)
• Control Modes: Hydraulic control (DA, HD, HW, etc.), electro-hydraulic proportional control (EP, EZ)
• Speed Range: 600–3000 rpm (dependent on model and operating conditions)
• Compatible Fluids: Mineral oil (standard), environmentally friendly hydraulic fluids (model-specific)
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IV. Typical Applications
1. Construction Machinery
• Excavators: Control travel motors and slewing motors’ flow/direction.
• Cranes: Regulate luffing/hoisting mechanisms’ hydraulic speeds.
• Pavers: Maintain constant vibratory frequency for screed plates.
2. Agricultural Machinery
• Combine Harvesters: Adjust header height and threshing drum rotational speed.
• Tractors: Control hydraulic hitch lifting force.
3. Industrial Equipment
• Injection Molding Machines: Regulate clamping unit and injection unit speeds/pressures.
• Die-Casting Machines: Control clamping force and injection speed.
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V. Selection and Configuration Recommendations
1. Model Selection Based on System Pressure
• For systems ≤250 bar, prioritize A10VG28; for higher pressure/flow demands, select A10VG45.
2. Control Mode Matching
• Simple Applications: Choose mechanical (e.g., MD valve) or hydraulic control (e.g., DA valve) for cost efficiency and reliability.
• High-Precision Needs: Opt for electro-hydraulic proportional control (e.g., EP valve) for remote adjustment and automation integration.
3. Auxiliary Function Integration
• For systems requiring charge pumps or pilot control, consider models with built-in charge pumps (e.g., A10VG28 + A10VO45 combined pump).
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VI. Maintenance and Troubleshooting
1. Regular Inspections
• Monitor pump output pressure/flow to ensure proper DA3R valve regulation.
• Check hydraulic fluid cleanliness to prevent valve core blockage from contaminants.
2. Common Failures
• Unstable Flow: Worn valve core or failed spring in the DA3R valve—replace valve core assembly.
• Pressure Build-Up Failure: Verify pressure cut-off valve settings or check for system leaks.
3. Spare Parts Management
• Stock critical DA3R valve components (e.g., valve cores, springs, seals) to minimize downtime during repairs.
