A7V Series Variable Displacement Piston Pump: Comprehensive Overview
1. Product Classification & Design
• Type: Oblique-axis (swashplate-free) axial piston pump.
• Circuit Compatibility: Primarily designed foropen-loop hydrostatic transmission systems, though some variants support closed-loop applications.
• Key Structural Features:
• Ball-face oil distribution: Ensures automatic centering during operation, reducing wear and improving efficiency.
• Compact design: No cylinder block swing frame, enabling high power-to-weight ratios.
• Radial load resistance: The drive shaft can withstand radial forces, enhancing durability in harsh environments.
2. Core Technical Specifications
• Displacement Range: 20–250 cm³/rev (e.g., A7V20, A7V55, A7V117, A7V160, A7V250).
• Pressure Ratings:
• Rated Pressure: 35 MPa (5,075 psi).
• Peak Pressure: 40 MPa (5,800 psi).
• Speed Range:
• Minimum: 500 rpm.
• Maximum Continuous: Up to 2,500 rpm (varies by model).
• Intermittent Peak: Up to 3,000 rpm for short durations.
• Operating Temperature: -25°C to 80°C (-13°F to 176°F).
• Viscosity Range: 10–1,000 mm²/s (optimal: 16–25 mm²/s).
3. Control Modes & Functionalities
The A7V series offersfive variable control methodsto adapt to diverse operational needs:
1. LV (Constant Power Control):
• Maintains hydraulic power output by adjusting flow based on load pressure.
• Ideal for applications requiring consistent power delivery, such as cranes and presses.
2. DR (Constant Pressure Control):
• Limits system pressure to a preset value, preventing overload.
• Suitable for systems needing pressure stability, like injection molding machines.
3. EP (Electro-Proportional Control):
• Enables remote electronic adjustment of flow/pressure via proportional valves.
• Used in automated machinery and precision equipment.
4. HD (Hydraulic Proportional Control):
• Uses hydraulic signals to regulate pump displacement.
• Common in multi-pump systems or where electrical control is impractical.
5. MA (Manual Control):
• Mechanical adjustment via levers or handwheels.
• Preferred for simple systems or maintenance scenarios.
4. Performance Advantages
• High Efficiency: Ball-face distribution and low circumferential speeds reduce friction losses.
• Compact & Lightweight: Smaller footprint compared to traditional pumps, saving space.
• Low Noise: Optimized flow paths and precision manufacturing minimize operational noise.
• Long Service Life: Robust bearing systems and radial load resistance extend component lifespan.
• Versatile Mounting: Flexible installation options (horizontal/vertical) simplify system integration.
5. Typical Applications
• Construction & Mining: Drives hydraulic systems in excavators, loaders, and drilling rigs.
• Metallurgical Industry: Powers rolling mills, forging presses, and material handling systems.
• Marine Vessels: Used in winches, steering gears, and deck machinery.
• Industrial Automation: Integrates with CNC machines, presses, and testing equipment.
• Mobile Machinery: Fuel-efficient drives for concrete mixers, agricultural tractors, and municipal vehicles.
6. Maintenance & Operational Guidelines
• Oil Quality: Use mineral-based hydraulic oil with viscosity grades matching ambient temperatures.
• Filtering: Install 10μm filters to prevent contaminants from entering the pump.
• Oil Replacement: Change hydraulic oil every 1,000–3,000 operating hours or six months.
• Mounting: Ensure the pump inlet is above the oil level to avoid cavitation. Use 90° elbows to reduce noise if installed on a tank.
• Troubleshooting:
• Vibration/Noise: Check for misalignment, worn bearings, or air ingestion.
• Overheating: Verify oil viscosity, filter cleanliness, and cooling system efficiency.
• Leakage: Inspect seals, pipe connections, and internal clearances.
7. Model Selection Guide
• Light-Duty (20–55 cm³/rev): Suitable for low-flow applications like lubrication systems or small actuators.
• Medium-Duty (78–117 cm³/rev): Balances flow and pressure for general-purpose machinery.
• Heavy-Duty (160–250 cm³/rev): Designed for high-power systems, such as primary drives in mining equipment.
