Slew Problem on Kobelco SK75UR: Troubleshooting and Solutions

[MikePhua]

The Kobelco SK75UR is a popular compact excavator known for its powerful performance and reliability. However, some operators may encounter issues with the slew function—the rotation of the upper structure relative to the undercarriage. In this article, we’ll explore common slew problems with the Kobelco SK75UR and provide potential solutions to help you diagnose and resolve these issues.
1. Understanding the Slew Mechanism
The slew mechanism on an excavator controls the rotation of the upper body, which includes the boom, arm, and bucket. This function allows the operator to rotate the upper structure 360 degrees, providing flexibility when maneuvering the machine. The slew system is powered by hydraulic motors and pumps, and any issues with it can affect the machine’s overall operation.
2. Common Slew Problems on Kobelco SK75UR
Operators of the Kobelco SK75UR might experience a few specific problems with the slew function, including:

• Sluggish or Weak Slew Performance: The slew function may rotate slower than usual or not respond with enough force. This issue can occur due to insufficient hydraulic power or wear in key components.
  
• Uneven Slew Movement: If the slew motor or hydraulic system is malfunctioning, it may result in uneven rotation. The machine might rotate in jerky motions or fail to rotate smoothly.
  
• Slew Motor Failure: Over time, the slew motor can wear out or become damaged, which may cause it to malfunction completely. A failed motor often requires replacement.
  
• Hydraulic Fluid Leaks: Leaks in the slew motor or hydraulic lines can result in a loss of pressure, causing weak or intermittent slew function.
  

3. Possible Causes of Slew Problems
There are several factors that could contribute to slew issues on a Kobelco SK75UR:

• Hydraulic System Issues: The hydraulic system plays a crucial role in controlling the slew function. Low hydraulic fluid levels, contaminated fluid, or a faulty hydraulic pump can reduce performance.
  
• Worn Slew Motor: Over time, the slew motor may experience wear and tear, which can affect its efficiency. Worn seals or bearings inside the motor can cause it to perform poorly or fail altogether.
  
• Damaged Hydraulic Lines or Hoses: Cracked or leaking hydraulic lines can cause a loss of pressure, reducing the effectiveness of the slew motor and slowing down rotation.
  
• Faulty Controls: Issues with the electronic control system or the slew joystick can also contribute to malfunctioning slew movements. Faulty wiring or sensor malfunctions can prevent the proper operation of the slew function.
  
• Low Hydraulic Pressure: Insufficient pressure in the hydraulic system can prevent the slew motor from performing as expected. This can be caused by an issue with the hydraulic pump or a blocked filter.
  

4. Diagnosing the Issue
To determine the root cause of the slew problem on your Kobelco SK75UR, follow these diagnostic steps:

• Check Hydraulic Fluid Levels: Low or contaminated hydraulic fluid can lead to poor slew performance. Ensure that the fluid is at the correct level and inspect it for any signs of contamination, such as dirt or metal particles.
  
• Inspect the Slew Motor: Examine the slew motor for signs of wear or damage. Check for leaks, unusual noises, or irregular movement during operation. A visual inspection of the motor can reveal issues with the seals, bearings, or housing.
  
• Test the Hydraulic Pressure: Use a pressure gauge to check the hydraulic pressure in the slew system. If the pressure is too low, the problem may be with the pump, filter, or pressure regulator.
  
• Inspect Hydraulic Lines: Check for any leaks or damage in the hydraulic lines or hoses that supply the slew motor. A leaking hose can cause a loss of pressure and hinder the rotation of the upper structure.
  
• Check the Control System: Inspect the electrical components controlling the slew function. Look for faulty wiring, malfunctioning sensors, or issues with the joystick controls. If there is an issue with the electronics, it may prevent the correct operation of the slew function.
  

5. Potential Solutions
Once you’ve identified the problem, there are several potential solutions to consider:

• Replace or Repair the Slew Motor: If the slew motor is worn or damaged, it may need to be replaced. Sometimes, the motor can be repaired by replacing damaged seals or bearings, but replacement is often more cost-effective.
  
• Fix Hydraulic Leaks: If there are any hydraulic leaks, the affected lines or hoses should be replaced. Sealing leaks in the hydraulic system will restore the necessary pressure for the slew function to work correctly.
  
• Change Hydraulic Fluid: If the fluid is contaminated or low, replacing it with fresh, clean hydraulic fluid can improve performance. Be sure to also replace the hydraulic filters to prevent further contamination.
  
• Repair or Replace Faulty Controls: If the issue lies within the control system, repairing or replacing faulty sensors, wiring, or the joystick controls should restore proper slew function.
  
• Adjust Hydraulic Pressure: If the hydraulic pressure is too low, it may be necessary to adjust the pump or replace a malfunctioning filter. Ensure the pressure meets the manufacturer’s specifications for optimal performance.
  

6. Preventative Maintenance
To prevent future slew issues with your Kobelco SK75UR, follow these preventative maintenance tips:

• Regularly Check Hydraulic Fluid Levels: Ensure the hydraulic fluid is at the correct level and is free of contamination. Regular fluid changes can prevent build-up of particles that could damage the system.
  
• Inspect Hydraulic Hoses and Fittings: Frequently inspect hoses and fittings for wear, cracks, or leaks. Replacing damaged hoses early can prevent more costly repairs down the road.
  
• Lubricate the Slew Motor: Regular lubrication of the slew motor and other moving parts can help prevent excessive wear. Follow the manufacturer’s maintenance schedule for proper lubrication intervals.
  
• Monitor Control Systems: Keep an eye on the electronic control system and replace any faulty components as soon as they are identified. Keeping the control system in good working order will ensure smooth and reliable slew operation.
  

7. Conclusion
Slew issues on the Kobelco SK75UR can be frustrating, but with the right diagnostic approach, you can pinpoint the cause and implement a solution. Whether it’s a problem with the hydraulic system, the slew motor, or the control electronics, addressing these issues early can save time and money in repairs. Regular maintenance and prompt repairs will ensure that your Kobelco excavator continues to perform at its best.