Slew Issue in Sunward SWE18UF: Diagnosis and Solutions

[MikePhua]

The Sunward SWE18UF is a compact yet powerful mini-excavator, known for its versatility and efficiency in tight spaces. However, like any piece of heavy machinery, it can occasionally develop issues that hinder its performance. One common problem that operators may encounter with the SWE18UF is related to the slew function. The slew refers to the machine’s ability to rotate its upper body (the superstructure) independently from the tracks, allowing it to move the boom and bucket around in a circular motion. When this function malfunctions, it can cause a range of operational difficulties. This article will delve into potential causes of slew issues in the Sunward SWE18UF, suggest possible diagnostic steps, and offer solutions to get your equipment back to optimal performance.
What is the Slew Function?
Before diving into troubleshooting, it’s essential to understand what the slew function does. The slew mechanism allows the upper part of the excavator (the cab, boom, arm, and attachment) to rotate on top of the tracked undercarriage. This rotation is critical for digging, lifting, and moving materials effectively. The slew motor is powered by hydraulics, meaning that any malfunction in the hydraulic system or the slew motor itself can lead to issues such as a lack of rotation or jerky, inconsistent motion.
Common Symptoms of Slew Issues
Slew issues on the Sunward SWE18UF can manifest in various ways. Recognizing the signs early can help prevent further damage and reduce downtime. Common symptoms include:

1. Slow or Jerky Slewing: If the excavator’s upper structure rotates sluggishly or in a jerky manner, it could indicate hydraulic issues or problems with the slew motor.
   
2. No Rotation: If the upper part of the excavator refuses to rotate entirely, the issue may lie with the hydraulic flow or the slew motor.
   
3. Uneven Slewing Speed: The machine may rotate at different speeds depending on the direction, indicating a malfunction in the hydraulic system or valves controlling the slew function.
   
4. Strange Noises: Unusual sounds, such as grinding or whining, can be a sign that the slew gears or motor have suffered damage or wear.
   

Diagnosing the Problem
To diagnose a slew issue, there are several steps you can take. These steps will help isolate whether the problem is hydraulic, mechanical, or electrical in nature.
1. Check Hydraulic Fluid Levels and Condition
The first thing to check when dealing with any hydraulic malfunction is the hydraulic fluid. Low fluid levels can cause the hydraulic pump to fail, which in turn affects the slew motor’s ability to operate.

• Low Fluid Levels: If the fluid is below the required level, it can cause cavitation, where air is sucked into the hydraulic system, leading to poor performance.
  
• Dirty Fluid: Contaminated fluid can clog filters and disrupt the hydraulic circuits, affecting the slew function. It is advisable to check the fluid’s color (which should be clean and clear) and its condition.
  

2. Inspect the Slew Motor
The slew motor is the heart of the rotation mechanism. If this motor is malfunctioning, it can cause slow, erratic, or no slewing. The motor should be checked for:

• Leaks: Hydraulic leaks around the slew motor can drain fluid, causing pressure loss.
  
• Motor Damage: Listen for unusual noises and check for excessive heat buildup, which can be signs of internal damage.
  

3. Check Hydraulic Valves
If the hydraulic fluid is in good condition, but the slew is still malfunctioning, the issue could lie in the control valves. The hydraulic control valve regulates the flow of fluid to the slew motor, and any blockage, wear, or malfunction in the valve can result in a lack of rotation.

• Clogged or Faulty Valve: A clogged valve can restrict fluid flow, leading to sluggish or no rotation.
  
• Valve Seal Issues: Worn-out seals can cause leaks, reducing pressure to the slew motor.
  

4. Examine the Slew Gearbox and Bearing
A mechanical failure in the slew gearbox or the bearing could also be the cause of your issue. The slew gearbox transfers power from the slew motor to the rotation mechanism. If it is damaged, the machine may fail to rotate properly.

• Damaged Gears: Check for signs of wear or chipped teeth in the gears that could be causing slipping or jerky movement.
  
• Worn Bearings: Bearings that are damaged or worn can prevent smooth rotation and cause unusual noises.
  

5. Electrical and Control System Check
If the hydraulic and mechanical components appear to be functioning properly, the issue may lie in the electrical or control system. For the Sunward SWE18UF, this would include:

• Faulty Joystick Controls: If the joystick controlling the slew is malfunctioning, it may send incorrect signals to the hydraulic system.
  
• Sensor Malfunctions: Some mini-excavators are equipped with sensors that monitor the slew motor’s position and speed. A malfunctioning sensor can disrupt the operation.
  

Possible Solutions to Fix Slew Issues
Once you have diagnosed the root cause of the slew problem, there are several potential solutions based on the issue identified.
1. Refill or Replace Hydraulic Fluid
If low or contaminated hydraulic fluid is the culprit, the solution is simple: top up or replace the hydraulic fluid. Ensure you are using the recommended fluid type and quantity as specified by Sunward in the user manual.
2. Repair or Replace the Slew Motor
For issues related to the slew motor, it may be necessary to replace the motor if it is severely damaged or malfunctioning. If the motor is leaking, repairing the seals might be enough to restore function.
3. Clean or Replace Hydraulic Valves
If a valve is found to be clogged or malfunctioning, clean the valve or replace it with a new one. This will restore the proper hydraulic flow needed for the slew function.
4. Repair the Slew Gearbox
If the gearbox or bearing is damaged, you may need to replace the gears or bearings. If the damage is too extensive, replacing the entire gearbox might be necessary.
5. Inspect and Repair Electrical Components
For issues with the electrical system, inspect all wiring, sensors, and control units for faults. Replacing malfunctioning sensors, fixing faulty wiring, or recalibrating the control system should solve most electrical issues.
Preventive Maintenance Tips
Regular maintenance can help prevent slew issues and extend the lifespan of your Sunward SWE18UF. Here are a few tips:

• Regularly check hydraulic fluid levels and ensure they are clean and free of contaminants.
  
• Perform regular inspections of the slew motor and gearbox, looking for leaks or signs of wear.
  
• Lubricate the slew bearing to ensure smooth and efficient operation.
  
• Test the electrical system periodically to catch potential issues early.
  

Conclusion
Slew issues in the Sunward SWE18UF can stem from a variety of causes, from hydraulic fluid problems to mechanical or electrical failures. By systematically diagnosing the issue, whether it’s a simple fluid level problem or a more complex mechanical fault, you can ensure that your mini-excavator is back to full working order quickly and efficiently. Regular maintenance and care can help prevent these issues from arising in the future, saving you both time and money on repairs.