Kubota R520 Intermittently Won’t Move: Troubleshooting Common Issues

[MikePhua]

The forum post discusses a recurring issue with the Kubota R520 skid steer loader, where the machine intermittently fails to move. Operators have shared their experiences and offered troubleshooting advice, highlighting potential causes of the problem. This issue is frustrating as it directly impacts the equipment's functionality, and timely resolution is critical for maintaining productivity.
Symptoms of the Issue
The Kubota R520 appears to have a problem where it will sometimes not move, even though the engine starts up and the hydraulics appear to be functioning. Symptoms mentioned by users include:

1. No Movement: Despite the engine running, the machine does not respond when the controls are engaged.
   
2. Intermittent Operation: In some instances, the loader will operate normally for a while but then suddenly stop moving or fail to engage.
   
3. Hydraulic Functioning but No Drive: The hydraulic system seems to work correctly, but the tracks or wheels do not engage as they should, indicating a problem with the drive mechanism.
   

Possible Causes and Troubleshooting Steps
Several potential causes were discussed by users who experienced this issue, and they provided some useful steps for troubleshooting:

1. Hydraulic Pressure Issues: One common cause could be a hydraulic pressure issue. The machine relies on hydraulic power to drive the wheels or tracks, and if there’s insufficient pressure, the drive system won’t engage. This can happen if there are issues with the hydraulic pump, valves, or hydraulic lines. Users suggested checking for any hydraulic fluid leaks or low fluid levels, as well as inspecting the pump for damage or wear.
   
2. Drive Motor Problems: Another likely culprit is the drive motor. The R520 uses hydraulic motors to power the wheels, and if one or both of these motors are malfunctioning or damaged, it can result in the machine not moving. A user recommended checking the hydraulic motors for signs of wear, leakage, or clogs.
   
3. Transmission or Drive Shaft Malfunctions: Some forum members noted that the issue might lie in the transmission system or drive shafts. If there is a malfunction in the drivetrain, such as a broken gear, loose coupling, or damaged drive shafts, the machine will fail to transmit power to the wheels or tracks. Regular maintenance of the transmission and drivetrain components is crucial for smooth operation.
   
4. Electrical or Control Issues: Electrical components and control systems also play a significant role in the machine’s operation. Problems with the wiring, solenoids, or electronic control units (ECUs) could be interfering with the proper operation of the drive system. One user noted that a faulty solenoid could fail to engage the drive system, causing intermittent operation. Diagnosing electrical issues requires checking the fuses, wiring, and control modules for any faults.
   
5. Clogged or Worn Filters: A less likely but possible cause could be clogged filters, particularly the hydraulic filter or fuel filter. Over time, dirt and debris can accumulate in filters, restricting the flow of fluid and potentially causing power loss. Users suggested inspecting the filters and replacing them if they are clogged or appear worn out.
   
6. Faulty Parking Brake: A potential issue that was discussed relates to a faulty parking brake. If the parking brake mechanism is not fully disengaging, it could prevent the machine from moving. One user recommended checking the parking brake and ensuring it releases completely when the machine is in use.
   

Step-by-Step Troubleshooting Process
Here are the steps to follow when troubleshooting this issue:

1. Check Hydraulic Fluid Levels: Start by inspecting the hydraulic fluid levels. Low fluid levels can lead to insufficient pressure, causing the machine to fail to move. Refill the hydraulic fluid if necessary, and check for any visible leaks in the system.
   
2. Inspect Hydraulic Pump and Lines: Examine the hydraulic pump for any damage or wear. Inspect all hydraulic lines for leaks or blockages that could be causing pressure issues. If the hydraulic pump is malfunctioning, it may need to be replaced.
   
3. Test Drive Motors: If the hydraulic system appears fine, test the drive motors. Listen for unusual sounds, and check for any signs of leakage or damage. If the motors are faulty, they may need to be replaced or serviced.
   
4. Check the Transmission and Drive Shaft: Inspect the transmission and drive shafts for any signs of damage, wear, or loose connections. Tighten or replace any damaged parts as needed.
   
5. Examine Electrical Components: Check the electrical system, including solenoids, wiring, and fuses. Look for any loose or corroded connections that could affect the operation of the drive system.
   
6. Inspect Filters: Check the hydraulic filters and fuel filters to ensure they are clean and not clogged. Replace any filters that appear worn or dirty.
   
7. Inspect the Parking Brake: Verify that the parking brake is fully disengaging when you attempt to move the machine. If the brake is stuck or malfunctioning, it may need to be adjusted or repaired.
   
8. Perform System Diagnostics: If the above steps do not resolve the issue, use a diagnostic tool to check for any error codes or issues with the machine’s electronic control systems. Fault codes can often provide a direct path to the root cause of the problem.
   

Preventative Maintenance Tips

1. Regular Fluid Checks: Make sure to regularly check the hydraulic fluid levels and filters. Low fluid levels or clogged filters are often the cause of intermittent movement issues.
   
2. Monitor Hydraulic System Health: Keep an eye on the hydraulic system, ensuring that the hydraulic pump and drive motors are functioning properly. Regular inspection can help catch issues early.
   
3. Electrical System Inspections: Periodically inspect the electrical components such as the wiring and control modules. Regular checks can help avoid unexpected electrical failures.
   
4. Drive System Maintenance: Keep the transmission and drive shafts properly maintained to prevent mechanical failures. Regular servicing can help avoid costly repairs down the line.
   
5. Follow Manufacturer Guidelines: Always adhere to the maintenance and operating guidelines provided by Kubota to ensure the longevity and proper functioning of your R520 skid steer loader.
   

Conclusion
The issue of a Kubota R520 skid steer intermittently failing to move can be traced back to several potential causes, including hydraulic problems, drive motor failure, electrical malfunctions, and clogged filters. By following the troubleshooting steps outlined above, operators can identify and resolve the issue. Regular maintenance, such as checking hydraulic fluid levels, inspecting drive components, and maintaining the electrical system, can help prevent future problems and keep the Kubota R520 running smoothly.