Troubleshooting Excavator Boom Stops When Using Dipper or Bucket

[MikePhua]

Introduction
Excavators are intricate machines that rely on a sophisticated hydraulic system to perform various tasks. One common issue operators may encounter is the boom stopping or becoming unresponsive when using the dipper or bucket. This problem can significantly impact productivity and may be indicative of underlying hydraulic or control system issues.
Understanding the Hydraulic System
Excavators operate using a hydraulic system that consists of a hydraulic pump, control valves, cylinders, and hydraulic fluid. The hydraulic pump generates flow, which is directed by control valves to various cylinders, allowing movement of the boom, dipper, and bucket. Each of these components must function correctly to ensure smooth operation.
Common Causes of Boom Stops When Using Dipper or Bucket

1. Hydraulic Flow Restrictions
   A common cause for the boom stopping when using the dipper or bucket is a restriction in the hydraulic flow. This can occur due to clogged filters, dirty hydraulic oil, or debris in the hydraulic lines. Such restrictions can impede the necessary flow of hydraulic fluid, leading to unresponsive boom movements.
   
2. Faulty Control Valves
   Control valves direct the flow of hydraulic fluid to the appropriate cylinders. If these valves become faulty or worn, they may not properly direct fluid, causing the boom to stop when the dipper or bucket is used. Issues such as sticking or leaking valves can disrupt the hydraulic balance and lead to operational problems.
   
3. Pilot Pressure Problems
   Many excavators utilize pilot-operated valves, which rely on pilot pressure to function. If there is a loss of pilot pressure due to leaks or faulty components, the control valves may not operate correctly, leading to the boom stopping during certain operations.
   
4. Hydraulic Cylinder Issues
   Worn or damaged hydraulic cylinders can cause uneven movement or stoppage of the boom. Internal leaks within the cylinders can lead to a loss of pressure, affecting the performance of the boom when using the dipper or bucket.
   
5. Electrical or Sensor Malfunctions
   Modern excavators often incorporate electronic controls and sensors to manage hydraulic functions. Malfunctions in these systems, such as faulty sensors or electrical connections, can lead to improper hydraulic operation, including the boom stopping when the dipper or bucket is used.
   

Diagnostic Steps

1. Inspect Hydraulic Filters and Oil
   Begin by checking the hydraulic filters for clogs and ensuring that the hydraulic oil is clean and at the proper level. Contaminated or low oil can restrict flow and cause operational issues.
   
2. Check Control Valves
   Test the control valves for proper operation. Listen for unusual noises, such as hissing, which may indicate leaks. Inspect for any signs of wear or damage that could affect valve performance.
   
3. Verify Pilot Pressure
   Measure the pilot pressure to ensure it is within the manufacturer's specifications. Low pilot pressure can prevent proper valve operation, leading to the boom stopping during certain functions.
   
4. Examine Hydraulic Cylinders
   Inspect the hydraulic cylinders for signs of leakage or damage. Check the seals and rods for wear, as these can affect cylinder performance and cause the boom to stop when using the dipper or bucket.
   
5. Test Electrical and Sensor Systems
   Check the electrical connections and sensors related to the hydraulic system. Ensure that all connections are secure and that sensors are providing accurate readings to the control system.
   

Preventive Maintenance Tips

• Regularly Change Hydraulic Filters
  Replace hydraulic filters at recommended intervals to prevent clogging and ensure proper fluid flow.
  
• Monitor Hydraulic Oil Quality
  Regularly check the hydraulic oil for contamination and replace it as needed to maintain system efficiency.
  
• Inspect Control Valves Periodically
  Conduct routine inspections of control valves to detect any signs of wear or malfunction early.
  
• Maintain Pilot Pressure
  Regularly verify pilot pressure levels to ensure that control valves operate correctly.
  
• Check Hydraulic Cylinders for Leaks
  Inspect hydraulic cylinders for leaks and replace seals as necessary to maintain system integrity.
  

Conclusion
Experiencing the boom stopping when using the dipper or bucket on an excavator can be indicative of various hydraulic or control system issues. By systematically diagnosing potential causes and performing regular maintenance, operators can ensure the continued efficient operation of their equipment. Addressing these issues promptly can prevent more severe problems and costly repairs in the future.