Diagnosing and Fixing Gear Shifting Issues on a 2013 LiuGong CLG856 Wheel Loader

[MikePhua]

Gear shifting issues in wheel loaders, such as the 2013 LiuGong CLG856, are not uncommon but can be highly disruptive to operations. These machines, designed for demanding construction and material handling tasks, rely heavily on smooth gear transitions to maintain productivity and efficiency. Any problems with gear shifting can lead to delays, increased wear on components, and even costly repairs if left unaddressed.
In this article, we’ll dive into common causes of gear shifting problems in the LiuGong CLG856 wheel loader, how to diagnose the issue, and the steps necessary for effective resolution. We'll also explore the importance of regular maintenance and proactive troubleshooting to keep your loader in top condition.
Understanding the Gear Shifting Mechanism in the LiuGong CLG856
The gear shifting system in a wheel loader like the LiuGong CLG856 plays a critical role in transferring power from the engine to the wheels. This system typically includes the transmission, clutch, and related components, which work together to provide the necessary torque and speed for the machine to perform various tasks.

1. Transmission and Gearbox
   • The LiuGong CLG856 uses a powershift transmission, a popular choice in heavy equipment for its ability to change gears without interrupting power flow. Powershift transmissions are known for providing smooth gear transitions and greater control in demanding applications.
     
2. Hydraulic Control
   • The gear shifting system is typically hydraulically controlled, meaning that fluid pressure is used to engage or disengage the clutch and shift gears. This allows for smoother transitions and reduces the strain on mechanical components.
     
3. Electronic Control
   • The newer models of the LiuGong CLG856, such as the 2013 version, may also integrate electronic control systems to manage shifting. These systems include sensors, solenoids, and electronic control units (ECUs) that optimize shifting performance based on operational demands.
     

Common Causes of Gear Shifting Problems
When a gear shifting issue occurs, it’s essential to pinpoint the exact cause. A variety of factors can contribute to shifting problems in a wheel loader, and understanding these potential issues is the first step in diagnosing the problem.

1. Low Transmission Fluid
   • One of the most common causes of shifting problems in wheel loaders is low or contaminated transmission fluid. The hydraulic system in the transmission relies on proper fluid levels to maintain pressure and operate the shift mechanism effectively. Low fluid can cause erratic shifting, slipping gears, or failure to shift at all.
     
2. Worn Clutch or Torque Converter
   • The clutch in a wheel loader’s powershift transmission is responsible for engaging and disengaging the transmission. If the clutch is worn out, it may fail to properly engage or disengage the gears, leading to difficult shifting or slipping. Similarly, issues with the torque converter can result in improper gear shifting behavior.
     
3. Faulty Shift Solenoids
   • Many modern loaders, including the LiuGong CLG856, use shift solenoids to control gear changes. These solenoids can wear out over time or become clogged with debris, causing erratic shifting or failure to shift altogether.
     
4. Sensor or Electronic Control Failure
   • Given the electronic control systems in newer models, issues with sensors or the electronic control unit (ECU) can lead to improper gear shifting. Faulty sensors may provide incorrect data, causing the ECU to mismanage gear selection.
     
5. Damaged or Clogged Transmission Filters
   • Transmission filters are designed to remove contaminants from the hydraulic fluid. If the filter becomes clogged or damaged, it can restrict fluid flow, leading to poor shifting performance or even transmission failure.
     
6. Mechanical Wear in the Transmission
   • Over time, the internal components of the transmission, such as gears, bearings, and shafts, can wear down. This wear can lead to slipping gears, difficulty shifting, or complete transmission failure.
     

Diagnosing Gear Shifting Issues
Diagnosing gear shifting problems in a LiuGong CLG856 wheel loader requires a systematic approach. Here are the steps to take when attempting to identify the root cause:

1. Check Fluid Levels and Quality
   • The first step in diagnosing shifting issues is to check the transmission fluid. Ensure the fluid is at the proper level, and inspect the fluid’s color and consistency. Fresh transmission fluid is typically red or pink, while contaminated fluid may appear brown or black.
     
2. Inspect the Clutch and Torque Converter
   • If the fluid levels are fine, the next step is to check the clutch and torque converter. Listen for any unusual noises or slipping when the loader attempts to shift. If the clutch feels unresponsive or the torque converter isn’t providing adequate power transfer, it may be time for a replacement.
     
3. Test the Shift Solenoids
   • Using diagnostic equipment, check the operation of the shift solenoids. A malfunctioning solenoid may not engage the correct gear or may cause the loader to get stuck in a gear. If you notice irregularities, the solenoids may need to be cleaned, repaired, or replaced.
     
4. Inspect Sensors and Electronic Control Systems
   • With the integration of electronic controls, sensors play a vital role in proper gear shifting. Use a diagnostic scanner to check for any fault codes related to the transmission control system. If sensors are providing inaccurate readings, they may need to be recalibrated or replaced.
     
5. Inspect the Transmission Filters
   • A clogged or damaged filter can restrict fluid flow, leading to shifting issues. Inspect the filter for debris or damage, and replace it if necessary. Clean fluid flow is essential for proper hydraulic operation.
     
6. Look for Mechanical Wear
   • Finally, if all the previous checks come back normal, consider inspecting the internal transmission components. Excessive wear or broken parts may require a more extensive repair or even a full transmission rebuild.
     

Steps for Fixing Gear Shifting Issues
Once you have identified the cause of the gear shifting issues, the next step is to address the problem. Depending on the issue, this may involve simple fluid replacement, solenoid cleaning, or more complicated repairs such as transmission overhauls. Below are the general steps for resolving common gear shifting issues:

1. Fluid Replacement
   • If the transmission fluid is low or contaminated, drain the old fluid and replace it with the recommended fluid. Be sure to replace the transmission filter as well to ensure that the new fluid remains clean.
     
2. Clutch and Torque Converter Replacement
   • If the clutch or torque converter is worn out, they will need to be replaced. This can be a labor-intensive process and may require removing the transmission from the loader. Work with a qualified technician to ensure that these components are replaced correctly.
     
3. Shift Solenoid Replacement
   • If faulty shift solenoids are identified, replace them with new or refurbished units. Make sure to test the solenoids after installation to confirm proper functionality.
     
4. Sensor Calibration or Replacement
   • If sensors are malfunctioning, calibrate or replace them using diagnostic tools. Faulty sensors can lead to inaccurate readings, so it's essential to fix these to prevent future shifting issues.
     
5. Transmission Overhaul
   • If mechanical wear inside the transmission is the culprit, a full transmission overhaul may be necessary. This could involve replacing worn gears, bearings, seals, and shafts. It’s advisable to consult with a specialist for this type of repair to ensure that the transmission is rebuilt to factory standards.
     

Preventing Future Gear Shifting Problems
To prevent gear shifting issues in the future, regular maintenance is crucial. Here are a few proactive steps to keep the LiuGong CLG856 wheel loader running smoothly:

1. Regular Fluid Checks
   • Check the transmission fluid regularly to ensure it is at the correct level and in good condition. Change the fluid as recommended by the manufacturer to prevent contamination and ensure smooth operation.
     
2. Timely Replacement of Filters
   • Change the transmission filters as part of routine maintenance to ensure fluid flows freely and contaminants are removed.
     
3. Monitor for Fault Codes
   • Regularly scan for fault codes using diagnostic tools. This can help identify potential issues with the transmission system before they cause significant damage.
     
4. Routine Inspection
   • Periodically inspect the clutch, torque converter, and solenoids for signs of wear. Catching problems early can prevent costly repairs down the line.
     

Conclusion
Gear shifting issues in the 2013 LiuGong CLG856 wheel loader can stem from a variety of causes, including low fluid, worn components, faulty solenoids, or sensor issues. Diagnosing these problems requires a systematic approach, with checks for fluid levels, mechanical wear, and electronic system functionality. Once the cause is identified, repairs can range from fluid replacement to complete transmission overhauls, depending on the severity of the issue.
Regular maintenance and proactive inspections are the best ways to prevent gear shifting problems and extend the life of your wheel loader. By staying on top of routine care, you can ensure that your LiuGong CLG856 continues to operate efficiently and effectively, reducing downtime and increasing productivity on the job site.