Troubleshooting Swing Issues in Komatsu PC35MR-2 Excavators

[MikePhua]

Introduction
The Komatsu PC35MR-2 is a compact hydraulic excavator known for its versatility and reliability in various construction and landscaping tasks. However, like all machinery, it can experience operational issues over time. One common problem reported by operators is related to the swing function, where the boom exhibits reduced power, unintended movement, or inconsistent braking behavior. Understanding the potential causes and solutions for these issues can help maintain the excavator's performance and longevity.
Symptoms of Swing Function Problems
Operators have observed several symptoms indicating potential issues with the swing function:

• Reduced Swing Power: The boom moves slowly or lacks the usual force, especially when attempting to swing heavy loads or operate on inclines.
  
• Unintended Swing Movement: The boom swings downhill when traveling across a slight slope, or it can be manually pushed to either side when on level ground.
  
• Inconsistent Swing Brake: Upon releasing the swing control lever, the swing brake engages abruptly, stopping the boom, but then seems to unlock after a short time, allowing movement as described above.
  

These symptoms suggest that the problem may lie within the hydraulic system, specifically the swing motor or associated components.
Potential Causes
Several factors can contribute to the swing issues experienced in the PC35MR-2:

1. Swing Motor Valve Malfunctions: The swing motor contains check valves and relief valves that regulate hydraulic pressure and flow. If these valves malfunction or become clogged, they can impede the swing motor's performance.
   
2. Hydraulic Pressure Issues: Low or inconsistent hydraulic pressure can affect the swing function. This may result from issues such as a faulty pump, air in the hydraulic lines, or leaks in the system.
   
3. Swing Brake System Problems: The swing brake system is designed to hold the boom in place when the control lever is released. If the brake components are worn or malfunctioning, they may not engage or disengage properly, leading to unintended movement or difficulty in stopping the boom.
   
4. Contaminated Hydraulic Fluid: Contaminants in the hydraulic fluid can cause wear and damage to internal components, leading to reduced performance and potential failure of the swing motor.
   

Diagnostic Steps
To accurately diagnose and address the swing function issues, consider the following steps:

1. Inspect Hydraulic Fluid: Check the hydraulic fluid levels and condition. Ensure that the fluid is clean and at the proper level. Contaminated or low fluid can lead to various hydraulic issues.
   
2. Bleed the Hydraulic System: Air trapped in the hydraulic lines can cause erratic behavior. Bleed the system to remove any air pockets and ensure smooth operation.
   
3. Test Hydraulic Pressure: Use a pressure gauge to test the hydraulic pressure at various points in the system. This can help identify any pressure-related issues affecting the swing function.
   
4. Examine Swing Motor and Valves: Inspect the swing motor for any signs of wear or damage. Check the check valves and relief valves for proper operation and cleanliness.
   
5. Evaluate Swing Brake Components: Assess the condition of the swing brake components, including the brake disc and actuator. Ensure they are functioning correctly and not causing unintended movement.
   

Repair and Maintenance Recommendations
Based on the diagnostic findings, the following actions may be necessary:

• Valve Replacement: If any check or relief valves are found to be faulty, replace them with OEM (Original Equipment Manufacturer) parts to restore proper hydraulic function.
  
• Hydraulic System Flushing: If contamination is detected in the hydraulic fluid, flush the system thoroughly and replace the fluid to prevent further damage.
  
• Swing Motor Overhaul: In cases of significant wear or damage to the swing motor, consider overhauling or replacing the motor to restore full functionality.
  
• Brake System Repair: Address any issues with the swing brake system by replacing worn components and ensuring proper adjustment to prevent unintended movement.
  

Conclusion
The swing function issues in the Komatsu PC35MR-2 excavator can stem from various hydraulic and mechanical factors. By systematically diagnosing the problem and addressing the underlying causes, operators can restore the excavator's performance and ensure its continued reliability on the job site. Regular maintenance and prompt attention to any operational anomalies are key to prolonging the lifespan of the equipment and minimizing downtime.