Hydraulic System Troubleshooting in Hitachi UH171 Excavators

[MikePhua]

The Hitachi UH171 excavator, a robust machine designed for heavy-duty tasks, relies heavily on its hydraulic system for efficient operation. However, like all complex machinery, it can encounter hydraulic issues that affect performance. Understanding these problems and their solutions is crucial for maintaining the excavator's functionality and longevity.
Common Hydraulic Problems

1. Loss of Hydraulic Functionality
   

A prevalent issue reported by operators is the complete loss of hydraulic functions. In some instances, previous owners have modified the system by removing and plugging large pumps, claiming the machine operated fine without them. Such modifications can lead to inadequate hydraulic pressure, rendering the system inoperative.

1. Absence of Pressure from Main Pumps
   

Another common problem is the lack of pressure from the main hydraulic pumps. This can be attributed to several factors, including:

• Pilot Gear Pump Failure: The pilot gear pump, which provides the necessary pressure for control circuits, may fail, leading to a loss of control over hydraulic functions.
  
• Clogged Filters: Over time, hydraulic filters can become clogged with debris, restricting fluid flow and causing pressure drops.
  
• Internal Leaks: Worn seals or damaged components within the pump can cause internal leaks, reducing efficiency and pressure.
  

Diagnostic Steps

1. Check Hydraulic Fluid Levels
   

Ensure that the hydraulic fluid is at the recommended level. Low fluid levels can lead to cavitation and pump damage.

1. Inspect for Leaks
   

Examine the hydraulic system for any visible leaks. Leaks can lead to a loss of pressure and fluid, affecting system performance.

1. Test Pump Output
   

Using a pressure gauge, test the output of the main and pilot pumps. Compare the readings with the manufacturer's specifications to determine if the pumps are functioning correctly.

1. Examine Filters
   

Inspect and replace hydraulic filters as necessary. Clogged filters can restrict fluid flow and cause pressure drops.
Repair and Replacement

• Pilot Gear Pump Replacement: If the pilot gear pump is faulty, it should be replaced with a genuine Hitachi part to ensure compatibility and reliability.
  
• Seal and Component Replacement: Worn seals or damaged components within the pumps should be replaced promptly to prevent further damage and maintain system pressure.
  
• Filter Replacement: Regularly replacing hydraulic filters can prevent clogging and ensure proper fluid flow.
  

Preventive Maintenance Tips

• Regular Inspections: Conduct routine inspections of the hydraulic system to identify potential issues before they become major problems.
  
• Use Quality Hydraulic Fluid: Always use the manufacturer's recommended hydraulic fluid to ensure optimal performance and longevity of the system.
  
• Timely Filter Changes: Replace hydraulic filters at regular intervals to prevent clogging and maintain proper fluid flow.
  
• Monitor System Pressure: Regularly monitor hydraulic system pressure to detect any drops that may indicate underlying issues.
  

Conclusion
Maintaining the hydraulic system of the Hitachi UH171 excavator is essential for its efficient operation and longevity. By understanding common hydraulic problems, performing regular diagnostics, and adhering to preventive maintenance practices, operators can ensure the continued performance and reliability of their equipment.