Hitachi EX200-2 Excavator with Slow/Low Power Retracting Boom and Arm Cylinders

[MikePhua]

Introduction
The Hitachi EX200-2 excavator is a powerful machine designed for various construction and digging tasks. However, some users report slow or low power retraction issues in the boom and arm cylinders. This problem can lead to inefficiency, affecting productivity. In this article, we will examine the potential causes of this issue, offer troubleshooting steps, and suggest possible solutions to restore full power to the boom and arm cylinders.
1. Understanding the Problem
When an excavator experiences slow or weak retraction in the boom and arm cylinders, it is often a result of insufficient hydraulic pressure, poor fluid flow, or mechanical failure. These issues can cause the excavator to perform at less than optimal levels, potentially slowing down operations and causing delays.
2. Possible Causes of Slow/Low Power in Boom and Arm Cylinders
Several factors can contribute to slow or low power retraction in the boom and arm cylinders of the Hitachi EX200-2 excavator. The most common causes include:

• Low Hydraulic Fluid Levels: Insufficient hydraulic fluid can significantly affect the performance of the boom and arm cylinders. Low fluid levels may prevent the hydraulic system from delivering the required pressure to operate the cylinders efficiently.
  
• Contaminated Hydraulic Fluid: Dirty or contaminated hydraulic fluid can clog filters and reduce fluid flow. Contaminants in the fluid can also cause excessive wear on the hydraulic components, leading to slow or weak retraction.
  
• Faulty Hydraulic Pump: The hydraulic pump is responsible for supplying pressure to the system. If the pump is malfunctioning or worn out, it may fail to provide the necessary pressure to the boom and arm cylinders, resulting in slow or weak retraction.
  
• Air in the Hydraulic System: Air trapped in the hydraulic system can reduce the efficiency of fluid flow, causing delays in cylinder retraction. This is commonly caused by fluid leaks or improper maintenance procedures.
  
• Worn or Damaged Cylinders: If the boom or arm cylinders are worn or damaged, they may not operate as intended. This can cause a loss of power during retraction, as well as leakage or other issues affecting the overall performance.
  
• Clogged or Worn Hydraulic Filters: Hydraulic filters are designed to remove impurities from the fluid. If these filters are clogged or excessively worn, they may restrict the flow of fluid to the cylinders, leading to weak or slow retraction.
  
• Valve Issues: The control valves regulate the flow of hydraulic fluid to the cylinders. If the valves are malfunctioning or not properly adjusted, they may prevent fluid from reaching the cylinders, resulting in low power retraction.
  

3. Troubleshooting Steps
To properly diagnose the issue, it is essential to follow a systematic troubleshooting process. Here are the key steps to take when addressing slow or low power retraction in the boom and arm cylinders:

• Step 1: Check Hydraulic Fluid Levels
  Start by checking the hydraulic fluid levels in the excavator. Low levels can prevent the system from generating the required pressure. If the fluid is low, top it up with the correct type of hydraulic fluid. Ensure that the fluid is free from contaminants.
  
• Step 2: Inspect Hydraulic Fluid Quality
  Examine the hydraulic fluid for any signs of contamination. If the fluid appears dirty or has a burnt smell, it is a sign that it needs to be replaced. Additionally, replace the hydraulic filters if they are clogged or damaged.
  
• Step 3: Inspect the Hydraulic Pump
  Check the hydraulic pump for proper operation. If the pump is not delivering the required pressure, it may need to be repaired or replaced. Listen for any unusual noises coming from the pump, which can indicate internal damage or wear.
  
• Step 4: Check for Air in the System
  Air in the hydraulic system can cause sluggish performance. To eliminate air, check for any visible fluid leaks and repair them. Once the leaks are fixed, bleed the system to remove any trapped air.
  
• Step 5: Inspect Boom and Arm Cylinders
  Check the boom and arm cylinders for signs of wear or damage. Look for any oil leaks around the cylinder seals, as this can indicate internal damage. If the cylinders are damaged, they may need to be repaired or replaced.
  
• Step 6: Inspect Control Valves
  Inspect the control valves for proper operation. If the valves are sticking or malfunctioning, they may need to be cleaned, repaired, or replaced.
  

4. Solutions to Fix the Slow/Low Power Issue
Once the cause of the slow or low power retraction is identified, the following solutions can be applied:

• Refill or Replace Hydraulic Fluid
  If the fluid is low or contaminated, refill or replace it with the correct type of hydraulic fluid. Ensure that the fluid is clean and free of contaminants to avoid further damage to the system.
  
• Replace the Hydraulic Pump
  If the hydraulic pump is malfunctioning, consider replacing it with a new one. Ensure that the new pump is compatible with the Hitachi EX200-2 excavator to provide the correct pressure for cylinder operation.
  
• Replace Worn Cylinders
  If the boom or arm cylinders are damaged, they will need to be rebuilt or replaced. Replacing the seals and components inside the cylinders can restore their functionality and improve retraction speed.
  
• Replace or Clean the Hydraulic Filters
  If the filters are clogged or worn, replace them with new ones. Keeping the filters clean ensures that the hydraulic fluid flows freely through the system, preventing further issues.
  
• Fix Fluid Leaks
  Repair any hydraulic fluid leaks to prevent air from entering the system. Leaks can cause a drop in pressure, leading to weak or slow retraction. Ensure that all connections are tight and free of damage.
  
• Adjust or Replace Control Valves
  If the control valves are malfunctioning, they may need to be cleaned or replaced. Properly functioning valves are essential for directing the hydraulic fluid to the cylinders.
  

5. Conclusion
Slow or low power retraction in the boom and arm cylinders of the Hitachi EX200-2 excavator can be caused by several factors, including low hydraulic fluid levels, contaminated fluid, faulty hydraulic components, or mechanical failure. By following a systematic troubleshooting approach and applying the correct solutions, operators can restore full power and efficiency to their excavator.
Regular maintenance, such as checking fluid levels, cleaning filters, and inspecting the hydraulic system, can help prevent issues from arising and ensure the continued performance of the machine. If the problem persists or requires complex repairs, it is advisable to consult a professional technician for further assistance.