PSV2-55T KAYABA Tandem Hydraulic Piston Pump

Product Overview

The PSV2-55T is a KYB / KAYABA tandem-type variable displacement hydraulic piston pump used in excavator and construction machinery hydraulic systems.

KYB’s official hydraulic documentation identifies the PSV family as variable-displacement, high-pressure piston pumps designed primarily for heavy-duty applications such as construction equipment. The PSV2 designation represents a tandem dual-pump configuration.

Public application and replacement-part references identify the PSV2-55T, including related numbers such as B0600-255493 and 20640-4351, as a KYB/KAYABA hydraulic pump used in excavator applications. References include Sumitomo SH-series machines and JCB JS-series equipment.

The tandem architecture integrates two pump sections into a common drive arrangement, allowing hydraulic flow to be supplied to different circuits. This configuration is well suited to excavator systems where multiple actuators may operate simultaneously.

For replacement and remanufacturing applications, engineering evaluation should go beyond basic mounting compatibility. Shaft configuration, hydraulic ports, regulator configuration, rotation and machine-specific hydraulic requirements should all be verified before installation.

Our replacement solution emphasizes in-place interchangeability and 100% simulated working-condition testing to reduce installation risk and improve field reliability.

Technical Specifications

Confirmed Engineering Information

• Model: PSV2-55T
• Related Model: PSV2-55T-2
• Related Identification: B0600-255493
• Related Part Number: 20640-4351
• Brand: KYB / KAYABA
• Pump Type: Variable-displacement hydraulic piston pump
• Configuration: Tandem / dual pump
• Pump Family: PSV2 Series
• Typical Application: Excavator and construction machinery
• Architecture: Axial piston / swash-plate type within the KYB PSV family
• Application References: Sumitomo SH-series and JCB JS-series equipment.

Parameters Requiring Exact Configuration Verification

• Displacement: Exact PSV2-55T-2 displacement should be confirmed from the original pump configuration
• Rated Pressure: Must be confirmed from the specific pump specification
• Peak Pressure: Must be confirmed from the specific pump specification
• Maximum Speed: Must be confirmed from the specific pump configuration
• Control Method: Must be confirmed from the regulator and nameplate
• Rotation: Must be confirmed from the actual pump
• Weight: Should be confirmed for the specific assembly rather than using an aftermarket generic value

This distinction is important because the basic PSV2-55T model number alone does not uniquely define every hydraulic and mechanical configuration. Public technical guidance recommends verifying the complete pump identification, machine model and hydraulic system before ordering.

Key Technical Advantages

Tandem Pump Configuration

The defining feature of the PSV2-55T is its tandem arrangement. Two pump sections are integrated into one mechanical drive system, providing separate hydraulic flow paths for different functions.

This architecture is particularly useful in excavator systems where work equipment, swing and auxiliary functions may require coordinated hydraulic power.

Variable-Displacement Piston Technology

KYB classifies the PSV family as variable and high-pressure piston pumps for heavy-duty machinery.

Variable displacement allows pump output to be adapted to system demand, supporting efficient hydraulic power delivery across changing operating conditions.

Precision Rotary Group

Available PSV2-55T component references identify major internal components including the cylinder block, piston shoes, valve plates, ball guide, retainer plate, swash plate, drive shaft and bearings.

These components directly influence volumetric efficiency, internal leakage, mechanical efficiency, noise and service life.

Heavy-Duty Excavator Application

KYB states that its piston pumps are primarily used in construction equipment and other applications requiring heavy-duty hydraulic performance. The PSV product family supports hydraulic control concepts including horsepower control and load-sensing within the broader product range.

For PSV2-55T replacement work, engineering validation should therefore consider not only mechanical fitment but also hydraulic response, pressure stability, leakage, temperature and regulator behavior.

In-Place Interchangeability

Our replacement approach focuses on in-place interchangeability, matching the original pump’s mechanical mounting, shaft connection, hydraulic ports and control configuration wherever applicable.

The objective is to provide a replacement pump that integrates into the existing machine without unnecessary hydraulic-system modification.

100% Simulated Working-Condition Testing

Every replacement unit can be validated through 100% simulated working-condition testing, with attention to:

• Flow response
• Pressure build-up
• Regulator response
• Leakage
• Noise
• Vibration
• Continuous-load stability

This testing philosophy is designed to reduce commissioning risk after field installation.

Application Areas

The PSV2-55T is associated with hydraulic systems used in:

• Sumitomo SH-series excavators
• Sumitomo SH120 applications
• JCB JS-series excavators
• Crawler excavators
• Construction machinery
• Excavator main hydraulic systems

Public application references include several Sumitomo SH models and JCB JS machines, but final compatibility must be confirmed against the complete machine and pump identification.

Expert Maintenance Tips

Verify the Complete Pump Identification

Before ordering or installing a PSV2-55T replacement, verify:

• Complete pump model code
• Nameplate information
• Part number
• Machine model
• Machine serial number
• Shaft configuration
• Hydraulic port arrangement
• Regulator/control configuration

Clean the Hydraulic System Before Commissioning

A piston pump replacement should not be treated as an isolated component replacement.

Inspect:

• Hydraulic oil cleanliness
• Suction line condition
• Return filter
• Hydraulic tank
• Hose and pipe contamination
• Metallic debris from the failed pump

Contamination left in the system can rapidly damage the replacement rotary group.

Prevent Air Ingress

Before startup, make sure the suction circuit is properly sealed and adequately supplied with hydraulic oil.

Check:

• Oil level
• Suction hose
• Hose clamps and connections
• Air leakage
• Pump priming condition

Insufficient inlet conditions may result in cavitation, abnormal noise and accelerated wear.

Commission Gradually

After installation, do not immediately operate the machine at full load.

A controlled commissioning sequence should include:

Low-load operation → leakage inspection → pressure verification → actuator testing → progressive load increase.

This approach helps identify regulator mismatch, hydraulic restrictions and installation-related problems before they become major failures.

Investigate Abnormal Noise Systematically

If the PSV2-55T develops abnormal noise or flow instability, do not immediately assume internal pump failure.

First inspect:

• Suction restriction
• Air ingestion
• Oil level
• Oil condition and viscosity
• Suction hose collapse
• Tank aeration

Many apparent pump failures originate from hydraulic supply conditions rather than the pump’s internal rotary group.