Diagnosing Uneven Track Speed on a Volvo EC210BLC

[MikePhua]

The Importance of Balanced Track Performance
Excavators rely on synchronized track movement for precise maneuvering, especially in confined spaces or during slope work. When one track moves slower than the other, it disrupts steering, increases wear, and can signal deeper hydraulic or mechanical issues. On the Volvo EC210BLC, a mid-size crawler excavator introduced in the early 2000s, uneven track speed is a common symptom that demands careful diagnosis.
Volvo EC210BLC Overview
The EC210BLC was part of Volvo Construction Equipment’s push into the global excavator market, combining Scandinavian engineering with Japanese hydraulic systems. Built between 2002 and 2006, this model featured:

• Operating weight: Approx. 21 tons
  
• Engine: Volvo D6D EBE2, 150 hp
  
• Max digging depth: Around 6.7 meters
  
• Hydraulic flow: Up to 2 × 210 L/min
  
• Travel speed: Up to 5.5 km/h
  

Volvo CE, founded in 1832 and headquartered in Gothenburg, Sweden, became a major player in the heavy equipment sector after acquiring Samsung’s construction division in 1998. By 2005, the EC210 series had sold over 30,000 units globally, with strong adoption in Asia, Europe, and North America.
Common Causes of Uneven Track Speed
When one track moves slower than the other, the issue can stem from several sources:

• Final drive failure: The planetary gear system at the end of the track motor may be worn or contaminated.
  
• Hydraulic motor imbalance: Internal leakage or wear in one travel motor can reduce torque output.
  
• Control valve malfunction: The travel spool may be sticking or partially blocked, affecting flow to one side.
  
• Pilot pressure loss: Inconsistent pilot signal can cause delayed or weak response in one motor.
  
• Track tension discrepancy: Uneven tension increases drag, making one side appear slower.
  

Terminology notes:

• Final drive: The gear reduction unit that converts hydraulic motor rotation into track movement.
  
• Travel motor: A hydraulic motor dedicated to propelling each track.
  
• Pilot pressure: Low-pressure hydraulic signal used to control high-pressure functions.
  
• Travel spool: A valve component that directs flow to the travel motors.
  

Diagnostic Steps and Field Techniques
To pinpoint the issue, technicians should follow a structured approach:

• Visual inspection: Check for leaks, loose fittings, or damaged hoses near the travel motors and final drives.
  
• Track tension check: Measure sag between the carrier roller and track; adjust to manufacturer specs.
  
• Swap travel hoses: Temporarily reverse hydraulic lines to see if the issue follows the motor or stays with the side.
  
• Pressure testing: Use gauges to compare output pressure from both travel circuits under load.
  
• Pilot signal verification: Confirm consistent voltage or pressure from the joystick to the travel valve.
  

In one case from a quarry in British Columbia, a Volvo EC210BLC showed sluggish movement on the left track. After ruling out mechanical drag, technicians discovered a partially collapsed pilot hose that restricted signal flow. Replacing the hose restored full speed and saved the operator from replacing a $4,000 travel motor unnecessarily.
Hydraulic System Complexity and Wear Patterns
The EC210BLC uses a closed-center hydraulic system with load-sensing capabilities. This means flow is distributed based on demand, and any internal leakage can affect performance across multiple functions. Travel motors are especially vulnerable due to high torque loads and frequent directional changes.
Wear indicators include:

• Excessive heat on one motor or final drive
  
• Metallic particles in hydraulic filters
  
• Delayed response when switching directions
  
• Audible whining or grinding noises during travel
  

If the issue is traced to the travel motor, options include:

• Rebuilding the motor with OEM seal kits
  
• Replacing with a remanufactured unit
  
• Upgrading to newer-generation motors with improved tolerances
  

Control Valve and Spool Issues
The main control valve block contains multiple spools, each directing flow to a specific function. If the travel spool is sticky or partially obstructed, it can reduce flow to one motor. Cleaning the spool and checking for burrs or contamination is essential.
In dusty environments, such as demolition sites or cement plants, fine particles can enter the hydraulic system during maintenance. Using clean tools, sealed fluid containers, and proper flushing procedures can prevent spool damage.
Electrical and Sensor Considerations
While the EC210BLC is primarily hydraulic, it does rely on electrical signals for pilot control. Faulty joystick sensors, broken wires, or corroded connectors can cause inconsistent travel commands. A multimeter and wiring diagram are invaluable for tracing signal continuity.
In 2020, a contractor in Malaysia reported intermittent slow travel on the right track. After replacing the travel motor and control valve with no improvement, they discovered a corroded connector under the cab floor. Cleaning and resealing the connector resolved the issue instantly.
Preventive Maintenance and Recommendations
To avoid uneven track speed and related failures:

• Change hydraulic filters every 500 hours
  
• Inspect pilot hoses quarterly for soft spots or kinks
  
• Flush hydraulic fluid annually or after contamination events
  
• Use OEM-grade seals and fittings during repairs
  
• Train operators to avoid sharp directional changes at full speed
  

Conclusion
Uneven track speed on a Volvo EC210BLC is more than a nuisance—it’s a signal that something deeper may be wrong. Whether it’s hydraulic imbalance, mechanical wear, or electrical interference, a methodical approach to diagnosis can save time, money, and frustration. With proper maintenance and attention to system integrity, this excavator can continue delivering reliable performance across demanding job sites.