Restoring Hydraulic Function on the Takeuchi TB135

[MikePhua]

The TB135 and Its Compact Excavator Heritage
The Takeuchi TB135 is a 3.5-ton compact excavator introduced in the early 2000s, designed for precision trenching, grading, and utility work in confined spaces. Takeuchi, founded in Japan in 1963, pioneered the compact excavator segment and remains a global leader in mini-excavator design. The TB135 was part of a generation that emphasized hydraulic efficiency, operator comfort, and serviceability. With thousands of units sold across North America, Europe, and Asia, the TB135 became a trusted tool in rental fleets and contractor yards.
Its hydraulic system is powered by a variable displacement axial piston pump, typically manufactured by Sauer-Danfoss under OEM branding. This pump supplies pressure to the main control valve, travel motors, swing motor, and auxiliary circuits. The pump’s reliability is critical to the machine’s performance, and damage—whether from fire, contamination, or wear—can render the excavator inoperable.
Damage Assessment and Component Identification
In cases where the TB135 suffers external damage, such as fire exposure, the hydraulic pump may be compromised. Common signs include:

• Melted or missing hydraulic hoses
  
• Damaged solenoid coils or connectors
  
• Burned insulation or exposed wiring
  
• Cracked pump housing or warped mounting flange
  

The pump’s part number is typically stamped on a metal tag affixed to the body. For the TB135, one common part number is 1902022300, though variations exist depending on serial range. Internally, the pump includes:

• Swash plate and piston group
  
• Load-sensing compensator
  
• Solenoid-actuated displacement control
  
• Case drain and pressure ports
  

If the solenoids are damaged but the pump body remains intact, replacement coils may be sourced separately. However, some suppliers only offer complete pump assemblies, which can be prohibitively expensive.
Repair vs Replacement Strategy
Before replacing the entire pump, consider the following:

• Inspect the pump housing for cracks or warping
  
• Test the shaft for free rotation and bearing noise
  
• Check solenoid coil resistance and connector integrity
  
• Examine internal wear using a teardown or bench test
  

If the pump internals are sound and only the solenoids or hoses are damaged, a partial rebuild may be viable. Replacement coils can be sourced from Sauer-Danfoss distributors, often at lower cost than OEM-branded parts. Ensure compatibility by matching voltage, connector type, and mounting thread.
A contractor in Colorado once restored a fire-damaged TB135 by replacing the solenoids and hoses without removing the pump. The machine returned to full function after flushing the system and recalibrating the displacement control.
Hydraulic System Flushing and Contamination Control
After any pump-related repair, flushing the hydraulic system is essential. Fire damage can introduce soot, melted plastic, and metal debris into the fluid, which can damage valves and actuators.
Recommended steps:

• Drain all hydraulic fluid and replace filters
  
• Fill with flushing oil or low-viscosity hydraulic fluid
  
• Run the machine at low idle, cycling all functions
  
• Drain and inspect fluid for contamination
  
• Repeat until fluid remains clean
  
• Refill with manufacturer-recommended hydraulic oil
  

Use magnetic drain plugs and inline filters during the flushing process to capture fine particles. Avoid operating under load until the system is fully cleaned.
Sourcing Parts and Cross-Referencing
Takeuchi hydraulic pumps are often rebranded Sauer-Danfoss units. While the nameplate may show a Takeuchi part number, the internal components and solenoids match standard Danfoss catalog items. To reduce cost:

• Cross-reference the pump using serial and part number
  
• Contact Danfoss or authorized distributors for coil and valve specs
  
• Compare connector type (Deutsch, AMP, etc.) and voltage (12V or 24V)
  
• Verify thread pitch and mounting dimensions
  

In one case, a technician sourced replacement coils from a Danfoss distributor for 40% less than the OEM price. The parts matched perfectly and restored full pump control.
Preventative Measures and Long-Term Reliability
To protect the hydraulic pump and system:

• Inspect hoses and connectors monthly
  
• Replace damaged insulation or cracked fittings
  
• Use fire-resistant hydraulic hose sleeves in high-risk environments
  
• Install heat shields near exhaust and turbo components
  
• Maintain clean fluid with regular filter changes
  

Adding a hydraulic temperature gauge and pressure test ports can help monitor system health and detect early signs of pump wear or valve imbalance.
A Story from the Field
In 2021, a TB135 used in wildfire cleanup was exposed to radiant heat, melting its rear plastics and hydraulic lines. The pump solenoids were scorched, and the machine refused to operate. The owner feared a full pump replacement but discovered that the coils could be replaced individually. After sourcing parts through a Danfoss dealer and flushing the system, the excavator returned to service within a week—saving over $3,000 in parts and labor.
Conclusion
The hydraulic pump on the Takeuchi TB135 is a critical component, but not always a throwaway when damaged. With careful inspection, cross-referencing, and targeted repair, operators can restore function without full replacement. Understanding the pump’s internal structure, solenoid behavior, and contamination risks allows for smarter decisions and longer machine life. In compact excavation, precision and resilience go hand in hand—and the TB135 continues to prove its worth when maintained with care.