Troubleshooting Slow Bucket and Swing on Hitachi EX150 Excavator

[MikePhua]

When operating a hydraulic excavator like the Hitachi EX150, maintaining optimal performance is crucial for efficient operations, especially when performing tasks that demand quick and precise movements, such as digging and lifting. If you’ve noticed that the bucket and swing motions are slower than usual, it’s important to troubleshoot the issue promptly to avoid downtime and costly repairs.
This article will explore potential causes of slow bucket and swing movements in the Hitachi EX150, along with diagnostic steps, possible fixes, and preventative measures.
Understanding the Hydraulic System of the Hitachi EX150
The Hitachi EX150 is equipped with a sophisticated hydraulic system that powers several key functions of the machine, including the boom, bucket, and swing mechanisms. The system relies on a series of hydraulic pumps, motors, and valves to transfer power from the engine to these components.

• Hydraulic Pumps: These are responsible for generating hydraulic pressure that drives the movements of the machine.
  
• Hydraulic Motors: Motors convert hydraulic pressure into mechanical motion to operate the boom, bucket, and swing.
  
• Control Valves: These valves direct hydraulic fluid to various components based on the operator's inputs, allowing precise control over machine movements.
  

Understanding the key components of the hydraulic system is vital to diagnosing any issues affecting the machine’s performance.
Common Causes of Slow Bucket and Swing Movements
If the bucket and swing movements of your Hitachi EX150 are sluggish or unresponsive, the problem can usually be traced to a few common issues within the hydraulic system. Let’s take a look at the potential causes:
1. Low Hydraulic Fluid Levels
One of the simplest and most common causes of slow hydraulic functions is low hydraulic fluid levels. If there’s not enough fluid in the system, the hydraulic pumps and motors won’t receive adequate pressure, leading to sluggish or delayed movements.
Solution:

• Check the hydraulic fluid level regularly, especially before operating the excavator. If it’s low, refill it with the correct type of hydraulic oil recommended by Hitachi.
  
• Always inspect the fluid for any contamination, as dirty or degraded oil can cause blockages and inefficient performance.
  

2. Contaminated Hydraulic Fluid
Contaminants such as dirt, metal shavings, or water can enter the hydraulic system and cause blockages in the filters or damage to internal components like valves and pumps. Contaminated fluid can cause irregular pressure, leading to slow movements of the bucket or swing.
Solution:

• Change the hydraulic fluid at regular intervals as per the manufacturer’s maintenance schedule.
  
• Replace the hydraulic filters and inspect for any signs of contamination.
  
• Consider installing additional filtration systems if contamination is a recurring problem.
  

3. Worn Hydraulic Pump or Motor
The hydraulic pump and motor in the EX150 are responsible for generating and distributing the hydraulic power that drives the machine’s movements. If either of these components is worn or malfunctioning, it can result in reduced performance, including slower bucket and swing speeds.
Solution:

• Inspect the hydraulic pump for any signs of wear or leaks. If the pump is found to be faulty, it may need to be repaired or replaced.
  
• Similarly, check the hydraulic motor for any issues. If the motor is underperforming, consider replacing it to restore optimal functionality.
  

4. Damaged Control Valves
Control valves direct hydraulic fluid to the appropriate components based on the operator’s commands. If the valves become worn, dirty, or damaged, they can restrict fluid flow, leading to slow movements.
Solution:

• Inspect the control valves for any signs of leakage or damage. Clean and repair the valves as needed.
  
• Ensure that the valves are calibrated correctly to prevent any issues with fluid distribution.
  

5. Leaks in the Hydraulic System
Hydraulic leaks are one of the most common reasons for low pressure in the system. These leaks can occur in hoses, seals, or fittings, and they can reduce the amount of hydraulic fluid reaching key components, slowing the machine’s movements.
Solution:

• Perform a thorough inspection of all hydraulic hoses, fittings, and seals. Look for visible signs of leaks, such as fluid puddles or streaks of oil.
  
• Repair or replace any damaged hoses, seals, or fittings to prevent further fluid loss.
  

6. Faulty Swing Drive
The swing drive is a critical component that powers the rotation of the upper portion of the excavator. If the swing drive is faulty or the swing gears are worn, it can result in slow or erratic swing movements.
Solution:

• Inspect the swing drive for any signs of damage or malfunction. If the gears are worn or the drive is not functioning properly, it may need to be repaired or replaced.
  
• Lubricate the swing system regularly to reduce wear and tear and ensure smooth operation.
  

Diagnostic Steps for Identifying the Cause
To accurately pinpoint the cause of slow bucket and swing movements, follow these diagnostic steps:

1. Check Hydraulic Fluid Levels: Start by checking the fluid levels and topping up if necessary. Look for any signs of contamination.
   
2. Inspect for Leaks: Examine all hoses and fittings for leaks. If leaks are found, tighten or replace the damaged parts.
   
3. Test Hydraulic Pressure: Using a hydraulic pressure gauge, measure the system’s pressure output. If the pressure is too low, the pump or motor may be the culprit.
   
4. Inspect Control Valves: Test the valves for responsiveness. If they’re sticking or unresponsive, they may need cleaning or replacement.
   
5. Check the Swing Drive: Test the swing functionality by operating the excavator. If the swing is slow, the drive may need attention.
   

Preventative Maintenance Tips
Preventing issues with slow bucket and swing movements involves regular maintenance and attention to key components. Here are some helpful tips for keeping your Hitachi EX150 in top condition:

• Regular Fluid Checks: Monitor hydraulic fluid levels and condition regularly to ensure that the system operates efficiently.
  
• Scheduled Maintenance: Follow the manufacturer’s maintenance schedule to clean, replace, and inspect key components such as filters, pumps, and valves.
  
• Proper Lubrication: Ensure that all moving parts, especially in the swing system, are well-lubricated to minimize friction and wear.
  
• Timely Repairs: Address any minor issues as soon as they arise. Small problems, such as a slight leak or a slow control valve, can escalate into more significant issues if ignored.
  

Conclusion
Slow bucket and swing movements on the Hitachi EX150 can be caused by a variety of issues within the hydraulic system, including low fluid levels, contaminated fluid, worn pumps or motors, and leaks. By following the diagnostic steps outlined above, you can accurately identify the root cause and take the necessary steps to repair the issue.
Maintaining the hydraulic system and other key components of the excavator through regular servicing and preventative maintenance will not only keep your machine performing at its best but will also extend its lifespan and reduce the risk of costly repairs. With the right care, your Hitachi EX150 can continue to perform efficiently, ensuring your operations remain smooth and productive.