Diagnosing Hydraulic Power Loss on a Takeuchi TB135

[MikePhua]

The Takeuchi TB135 and Its Hydraulic System
The Takeuchi TB135 is a compact excavator introduced in the early 2000s by Takeuchi Manufacturing, a Japanese company founded in 1963 and known for pioneering the compact track loader. The TB135 features a zero-tail swing design, a 3.3-ton operating weight, and a dual-pump hydraulic system that powers travel, boom, arm, bucket, and auxiliary functions. With over 20,000 units sold globally, it remains a popular choice for contractors and rental fleets due to its reliability and maneuverability.
The hydraulic system in the TB135 uses two variable-displacement piston pumps, each supplying different circuits. Pump 1 typically powers travel and swing functions, while Pump 2 handles boom, arm, and bucket operations. The system includes a pilot circuit, control valves, and a return filter to maintain fluid cleanliness and pressure balance.
Symptoms of Hydraulic Failure
In one case, a 2007 TB135 with 2,000 hours began exhibiting erratic behavior:

• The machine curved during high-speed travel but tracked straight in low speed
  
• Bucket curl lost power, while boom lift remained strong
  
• Swapping pump hoses caused the boom to lose lifting ability
  

These symptoms suggest that one of the hydraulic pumps is failing internally, causing uneven pressure delivery and circuit imbalance. The fact that the boom could lift the machine before the hose swap but not after indicates that Pump 1 was compensating for Pump 2’s weakness.
Hydraulic Pump Failure Modes
Common failure modes in piston pumps include:

• Swash plate wear: Reduces displacement and flow
  
• Valve plate scoring: Causes internal leakage and pressure loss
  
• Piston ring damage: Leads to cavitation and erratic flow
  
• Bearing failure: Generates metal debris and contaminates fluid
  

In this case, the pump likely suffered from internal leakage, reducing output pressure and causing weak bucket curl. When hoses were swapped, the compromised pump was tasked with lifting, revealing its inability to generate sufficient force.
System Flushing and Contamination Control
Before installing a new pump, it’s critical to flush the hydraulic system to prevent debris from damaging the replacement. Recommended steps include:

• Drain all hydraulic fluid and inspect for metal particles or discoloration
  
• Replace return filters and pilot filters with OEM-grade elements
  
• Flush lines using clean hydraulic fluid under low pressure
  
• Inspect valve blocks and cylinders for signs of contamination
  
• Clean the tank and suction strainer thoroughly
  

Some technicians use a temporary inline filter during flushing to trap residual debris. Others recommend running the machine with clean fluid for 30 minutes, then draining and replacing again before installing the new pump.
Field Advice and Operator Stories
One operator in Oregon reported similar symptoms on a TB135 after a cold snap. The machine tracked unevenly and lost bucket power. After replacing Pump 2 and flushing the system, performance returned to normal. He noted that the pump failure was likely accelerated by moisture ingress and cold-start cavitation.
Another contractor in Alberta installed a used pump without flushing the system. Within 50 hours, the replacement failed due to contamination. He later switched to synthetic hydraulic fluid and added a magnetic drain plug to capture fine particles.
Preventive Maintenance Recommendations
To extend pump life and avoid future failures:

• Change hydraulic fluid every 1,000 hours or annually
  
• Replace filters every 500 hours
  
• Warm up the machine before operating in cold weather
  
• Inspect hoses and fittings quarterly for leaks or abrasion
  
• Use only manufacturer-approved fluids and components
  

Final Thoughts
Hydraulic pump failure in the Takeuchi TB135 can manifest subtly—uneven travel, weak bucket curl, or circuit imbalance. Diagnosing the issue requires understanding the dual-pump layout and pressure behavior. Replacing the pump without flushing the system risks repeating the failure. With proper diagnostics, contamination control, and preventive care, the TB135 can continue delivering reliable performance in demanding conditions.