A56-F-R-04-H-K-32 Yuken Piston Pump 56.2cc 210bar

Product Overview

The A56-F-R-04-H-K-32 is a Yuken A Series swashplate-type axial piston variable displacement pump. The A Series is Yuken’s classic product line, covering displacements from A10 through A70, and is widely used in industrial hydraulic systems and mobile equipment. The A56 model delivers a maximum displacement of 56.2 cm³/rev.

This model features flange mounting (SAE C) with right-hand rotation (clockwise when viewed from the shaft end) . The “04” control code denotes electro-hydraulic proportional load sensing (LS) control, which automatically matches output flow to system load demand for significant energy savings. The “H” pressure rating indicates a continuous operating pressure range of 1.5–21 MPa (210 bar) . The “K” shaft extension is a parallel key shaft of φ31.75 mm. The suffix “32” and extended designations (32366, 32393, etc.) represent different design versions or custom batches.

As a direct OEM-equivalent replacement solution for the Yuken A Series, this product offers complete in-situ interchangeability, strictly adhering to Yuken’s original design specifications and mounting interface standards (compliant with ISO 3019-2 and SAE J744). Every unit undergoes 100% simulated duty-cycle testing, ensuring that key performance metrics—including volumetric efficiency, pressure-flow characteristics, and case drain flow at rated pressure and full displacement—meet or exceed original factory specifications.

Technical Specifications 

• Model Number: A56-F-R-04-H-K-32 (and variants A56-F-R-04-H-K-32366 / A56-F-R-04-H-K-32393)

• Brand Series: Yuken A Series

• Pump Type: Swashplate Axial Piston Variable Displacement Pump

• Maximum Displacement: 56.2 cm³/rev (56.2 ml/rev)

• Rated Pressure (Continuous): 21 MPa (210 bar)

• Maximum Pressure (Peak): 25 MPa (250 bar)

• Rated Speed: 1800 rpm

• Speed Range: 600–1800 rpm

• Control Type: 04 – Electro-hydraulic Proportional Load Sensing (LS)

• Mounting Type: F – Flange Mounting (SAE C)

• Rotation Direction: R – Right-hand (clockwise from shaft end)

• Pressure Grade: H – 1.5–21 MPa (210 bar) Continuous High Pressure

• Shaft Type: K – Parallel Key Shaft φ31.75 mm

• Volumetric Efficiency: ≥ 98% (at 16 MPa, 1800 rpm)

• Overall Efficiency: ≥ 90% (at 16 MPa, 1800 rpm)

• Noise Level: ≤ 57 dB(A) (under low pressure conditions)

• Weight: Approx. 37 kg

• Port Connections: Standard Flange (Inlet φ50, Outlet φ32)

• Body Material: High-strength Cast Iron

• Hydraulic Fluid: Mineral Oil

• Recommended Filtration: 10 μm

Key Technical Advantages

1. Electro-Hydraulic Proportional Load Sensing for Significant Energy Savings
The “04” control configuration employs electro-hydraulic proportional load sensing technology, enabling the pump to deliver flow precisely matching system load demand—supplying oil only as needed. Compared to fixed-displacement pumps, this eliminates overflow losses and achieves energy savings of over 30%, while significantly reducing heat generation and extending hydraulic fluid service life.

2. High Volumetric Efficiency & Superior Energy Utilization
Under operating conditions of 16 MPa and 1800 rpm, the A56 delivers a volumetric efficiency of ≥ 98% and overall efficiency of ≥ 90%. High volumetric efficiency translates to minimal internal leakage, lower power loss, and reduced heat generation—directly lowering the operating costs of hydraulic systems.

3. Ultra-Quiet Operation for Improved Working Conditions
The A Series piston pumps excel in noise control. The A56 achieves a noise level of ≤ 57 dB(A) under low pressure conditions. This low-noise design not only improves operator comfort but also reduces noise pollution in the workplace.

4. Broad Flow Adjustment Range & Exceptional Control Flexibility
The A56 enables stepless flow adjustment from 0 to 56.2 cm³/rev. The electro-hydraulic proportional control interface supports integration with PLCs or dedicated controllers for precise closed-loop flow control—particularly advantageous for complex hydraulic systems requiring multi-action coordination.

5. Robust Heavy-Duty Construction & Flexible Mounting Configurations
The high-strength cast iron body combined with swashplate axial piston design delivers compact dimensions and exceptional load-bearing capacity. The flange mounting (SAE C) with parallel key shaft configuration ensures compatibility with major global hydraulic systems. The A Series complies with ISO 3019-2 and SAE J744 mounting standards, offering excellent interchangeability in the global market.

Application Areas

• Injection Molding Machines (Most Common): Replaces fixed-displacement or dual vane pumps, enabling independent flow control for injection, clamping, ejection, and mold adjustment—achieving 25–40% energy savings with reduced oil temperature

• Die-Casting Machines & High-Pressure Forming Equipment: High-pressure clamping (200–210 bar), high-speed injection, and stable holding pressure; load sensing reduces impact and extends mold life

• High-End CNC Machine Tools & Hydraulic Presses: Holding pressure, low-speed operation, high-speed return, and multi-axis synchronization for CNC bending machines, shearing machines, and hydraulic presses

• Construction & Mobile Equipment: Variable-displacement pump applications in mobile machinery hydraulic systems

• Marine Hydraulic Systems: Deck machinery and steering gear hydraulic systems

Expert Maintenance Tips

1. Model Confirmation & Pre-Installation Inspection: Prior to installation, confirm the complete model code. The A56-F-R-04-H-K-32 features flange mounting (SAE C) with a parallel key shaft of φ31.75 mm. Ensure alignment between the pump and drive mechanism meets SAE J744 or ISO 3019-2 standards to prevent premature bearing wear due to misalignment.

2. Fluid Cleanliness Control: The A Series piston pumps are more sensitive to fluid contamination than vane pumps—a minimum filtration rating of 10 μm is recommended. Perform complete system flushing before initial start-up to ensure system cleanliness.

3. Electro-Hydraulic Proportional Controller Tuning: The “04” control configuration is electro-hydraulic proportional load sensing. Commissioning requires coordination with a proportional amplifier or PLC controller. Parameter setting and calibration should be performed by technicians with experience in electro-hydraulic proportional control.

4. Inlet Condition Assurance: Ensure suction line inlet pressure meets the pump’s self-priming requirements. Keep suction lines as short and straight as possible, avoiding unnecessary bends and restrictions to prevent cavitation. Position the reservoir above or at the same level as the pump for optimal suction conditions.

5. Initial Start-Up & Priming: Before first start-up, pre-lubricate the pump by filling the housing with clean hydraulic fluid through the case drain port. After start-up, run the pump at low load for several minutes to purge air from the pump and system lines.

6. Scheduled Maintenance & Filter Replacement: Follow the maintenance intervals specified in the Yuken A Series service manual. Pay particular attention to filter condition (10 μm recommended), fluid cleanliness, and seal integrity during routine inspections. Regular hydraulic fluid and filter replacement is essential for long-term reliable pump operation.