Product Overview
The PSVD2-21E is a 21 cc/rev displacement model from KYB’s PSVD2 series of variable displacement piston pumps, a high-efficiency hydraulic main pump assembly developed specifically for 2 to 5 ton class mini excavators. The PSVD2 series employs an integrated design of dual variable piston pumps + gear pump + trochoid pump, making it one of the most widely deployed main pump platforms in mini excavator hydraulic systems.
The PSVD2-21E features a swashplate-type axial piston variable displacement structure with dual pump displacements of 21 cc/rev each, rated operating pressure of 24.5 MPa (3,553 PSI), maximum system pressure of 27.0 MPa (3,916 PSI) and maximum input speed of 2400 rpm. The pump integrates total horsepower control and load sensing functions, automatically matching engine power to prevent overload while driving boom, arm, travel, swing and breaker functions through the built-in pilot pump and gear pump.
This pump is the original equipment main pump for Yanmar VIO55-5A, VIO55-5B, VIO55-6A, VIO55-6B and VIO60-6B mini excavators, corresponding to OEM part number B0600-21031 (replaces B0600-21016). Same-series models include the PSVD2-17E (for VIO45/VIO50/VIO55 series), PSVD2-27E (for VIO60/Kubota KX60 and other 5–6 ton equipment) and the PSVD2-21E-23 and other solenoid-equipped variants.
Every PSVD2-21E unit undergoes 100% simulated operating-condition bench testing prior to shipment. Mounting flange, shaft end and port dimensions comply with SAE J744 standards and are identical to the original KYB PSVD2-21E, ensuring true drop-in interchangeability with zero modification required.
Technical Specifications
PSVD2 Series Frame Size Specifications:
PSVD2-12E: Dual piston pump displacement ~10.2–13.1 cc/rev, max input speed 2550 rpm, max pressure 24.5 MPa, suitable for 2.0–3.0 ton equipment
PSVD2-16E: Dual piston pump displacement ~14.2–16.8 cc/rev, max input speed 2500 rpm, max pressure 24.5 MPa, max input torque 85.3 N·m, suitable for 2.5–3.5 ton equipment
PSVD2-17E: Dual piston pump displacement 17 cc/rev ×2, rated pressure 24.5 MPa, peak pressure 26.5 MPa, speed range 1500–2500 rpm, suitable for Yanmar VIO45/VIO50/VIO55 and other 3.5–5 ton equipment
PSVD2-21E (This Model): Dual piston pump displacement 21 cc/rev ×2, rated pressure 24.5 MPa, peak pressure 27 MPa, max input speed 2400 rpm, max input torque 122.6 N·m, suitable for Yanmar VIO55/VIO60 and other 4–5.5 ton equipment
PSVD2-27E: Dual piston pump displacement ~26.9 cc/rev ×2, rated pressure 24.5 MPa, max input speed 2400 rpm, max input torque 140.2 N·m, suitable for Yanmar VIO60, Kubota KX60, IHI 60, Komatsu PC30-7 and other 5–6 ton equipment
PSVD2-21E Additional Specifications:
Model Code: PSVD2-21E
OEM Part Number: B0600-21031 (replaces B0600-21016)
Structure Type: Dual variable piston pump + gear pump + trochoid pump integrated main pump (Quad-Output)
Piston Pump Displacement (P1 & P2): 21.0 cc/rev × 2 (adjustable range 0–21 mL/rev)
Gear Pump Displacement (P3): Approx. 15.0 cc/rev (main gear)
Pilot Pump Displacement (P4): Approx. 5.0 cc/rev (trochoid)
Rated Operating Pressure: 24.5 MPa (3,553 PSI)
Maximum System Pressure: 27.0 MPa (3,916 PSI)
Maximum Input Speed: 2400 rpm
Rated Flow (at 2200 rpm): Approx. 46.2 L/min × 2 (main) + 33.0 L/min (gear) + 11.0 L/min (pilot)
Maximum Input Torque: 122.6 N·m
Control Type: Total horsepower control / load sensing compatible, pressure-compensated variable control
Rotation: Clockwise as seen from input shaft
Suction Pressure: -0.03 to +0.03 MPa
Fluid Temperature Range: -10°C to +80°C
Fluid Viscosity Range: 0.001–0.1 m²/s (10–100 cSt)
Case Drain Port: None (self-balancing case pressure design)
Pilot Relief Valve Setting: 3.9 MPa
Main Relief Valve Setting (P1/P2): 24.5 MPa
Travel/Blade Pressure (P3): 21.0 MPa
Case Drain Pressure Limit: Not to exceed 0.2 MPa (29 PSI)
Weight: ~26 kg (complete assembly with gear pump and pilot pump)
Applicable Equipment Weight: 4.0–5.5 ton mini excavators
Key Technical Advantages
1. Total Horsepower Control for Automatic Engine Power Matching
The PSVD2-21E’s core control strategy is Total Horsepower Control, where pump displacement is automatically adjusted based on engine speed and load, ensuring engine output power is fully utilized without overload. When load increases, the pump automatically reduces displacement to maintain stable engine speed; when load decreases, the pump increases displacement to accelerate operation. This enables efficient and smooth operation of mini excavators across combined digging, traveling and swinging conditions while reducing fuel consumption.
2. Integrated Four-Pump Structure for Independent Multi-Circuit Drive
The PSVD2-21E integrates two variable piston pumps, one gear pump and one trochoid pilot pump into a single unit, with a single common suction port divided into 4 pump suction areas inside the case. The dual piston pumps drive travel and work functions respectively, the gear pump provides auxiliary circuit flow, and the pilot pump supplies stable pilot pressure for the control system. This integrated design significantly shortens the pump assembly length, ideal for the compact engine compartments of mini excavators.
3. Swashplate Variable Structure and Low Noise Design
The PSVD2-21E employs a swashplate-type axial piston variable displacement structure, precisely controlling swashplate angle through a servo regulator to adjust displacement. Precision-ground swashplate and valve plate paired with high-precision piston groups effectively reduce flow pulsation and operating noise. The pump features a short overall length, a common suction port design, and no case drain port, simplifying piping. These design features result in noise levels superior to comparable products in enclosed engine room environments.
4. High Pressure Durable Design and Long Service Life
The PSVD2-21E’s pressure-bearing components (valve plate, slipper, cylinder block) use high-strength wear-resistant materials with 24.5 MPa rated pressure and 27 MPa peak pressure, suitable for continuous heavy-duty operation. The piston group uses precision grinding with hydrodynamic oil film design, maintaining high volumetric efficiency (typically ≥92%) and total efficiency (≥88%) under high-pressure conditions. The lightweight, simple structure and reduced part count design philosophy further enhance pump reliability and reduce maintenance costs.
5. 100% Simulated Load Testing & Drop-In Interchangeability
Each PSVD2-21E unit is bench-tested under simulated operating conditions prior to shipment, covering pressure cycling, displacement response, control signal calibration and thermal variation. Mounting flange, shaft spline and port dimensions comply with SAE J744 standards, matching the original KYB PSVD2-21E exactly, enabling direct replacement without any interface modification.
Application Areas
The PSVD2-21E hydraulic main pump is widely deployed in small construction machinery:
Yanmar Mini Excavators: VIO55-5A, VIO55-5B, VIO55-6A, VIO55-6B, VIO60-6B (OEM main pump, part number B0600-21031)
Same-Series Model Applications:
PSVD2-17E: Yanmar VIO45, VIO50, VIO55 series (3.5–5 ton)
PSVD2-27E: Yanmar VIO60, Kubota KX60, IHI 60, Komatsu PC30-7, Takeuchi TB145/TB153/TB160C (5–6 ton)
Other Mini Excavators: Kubota, IHI, Takeuchi, Sunward and other 4–6 ton equipment (verify mounting interface and solenoid configuration)
Small Construction Machinery: compact loaders, mini rotary drills, agricultural excavators
Expert Maintenance Tips
1. Housing Priming Before First Startup (Mandatory): Before first startup after installation, fill the pump housing with clean hydraulic fluid through the highest case drain port. Running an axial piston pump dry—even for a few seconds—will score the valve plate and piston slippers, causing immediate total pressure loss. After priming, loosen the air bleed port on top of the pump housing. Crank the engine with the fuel supply disabled until clear, bubble-free oil flows from the port, then retighten. Allow the machine to idle under no load for 10 to 15 minutes to purge trapped air.
2. System Cleaning and Filter Replacement: If replacing a pump that suffered internal mechanical failure, completely drain and clean the main hydraulic oil reservoir, flush all circuit lines and clean the oil cooler. Replace all return and suction filter elements before starting the engine. Maintain system fluid cleanliness at ISO 4406 18/16/13 or better.
3. Pilot Pressure and Main Relief Valve Verification: Verify system pressure relief valve settings upon startup. The main relief (P1/P2) setting is 24.5 MPa, travel/blade pressure (P3) is 21.0 MPa, and pilot control pressure (P4) is 3.9 MPa. Incorrect pressure settings can lead to sluggish hydraulic response, circuit overheating or abnormal actuator operation. Use calibrated pressure gauges for verification.
4. Fluid Cleanliness and Temperature Control: Maintain system fluid cleanliness at ISO 4406 18/16/13 or better. Operating oil temperature should be kept below 80°C, with fluid temperature range of -10°C to +80°C. Replace hydraulic oil and filter after the first 500 hours, then follow a 2,000-hour or annual replacement cycle. Case drain pressure must not exceed 0.2 MPa (29 PSI).
5. Periodic Displacement Control Mechanism Inspection: The PSVD2-21E’s swashplate, servo regulator and displacement control valve are primary wear components. Inspect swashplate working surface wear, piston slipper wear and servo piston seal integrity every 2,000 hours. If displacement response is sluggish, flow is insufficient, or abnormal noise or vibration is observed, shut down immediately for service. Use KYB original specification parts when replacing piston groups or servo seals.
