Troubleshooting Steering Issues in the Caterpillar 955L Track Loader

[MikePhua]

The Caterpillar 955L track loader, introduced in the mid-20th century, is renowned for its durability and versatility in various construction and agricultural applications. However, like all heavy machinery, it is susceptible to mechanical issues over time. One common problem operators encounter is steering failure, which can manifest as unresponsiveness or difficulty in turning. Understanding the underlying causes and implementing appropriate solutions is crucial for maintaining the machine's performance.
Understanding the Steering Mechanism
The 955L utilizes a pedal-operated steering system, where each track is controlled independently through steering clutches and brakes. Hydraulic pressure, typically around 450–650 psi, is applied to release the steering clutches, allowing the operator to maneuver the loader. A failure in this system can result from various factors, including hydraulic issues, mechanical failures, or linkage problems.
Common Causes of Steering Failures

1. Hydraulic System Issues: A common cause of steering problems is air in the hydraulic lines, often resulting from low oil levels or leaks. For instance, running the steering assist out of oil can lead to the system losing its prime, making it difficult to steer. Operators have reported that after adding oil, they still experienced issues due to trapped air in the lines.
   
2. Steering Clutch Failures: The steering clutches themselves can wear out over time. Symptoms include the loader steering fine when cold but becoming unresponsive as it warms up. In such cases, the clutch packs may need to be replaced, which involves significant disassembly and reassembly of the machine's components.
   
3. Linkage and Mechanical Failures: The mechanical linkages connecting the pedals to the steering clutches can become worn or disconnected. This can lead to a situation where the pedal moves freely without engaging the clutch, rendering the steering ineffective. Inspecting and adjusting these linkages is essential for proper operation.
   

Diagnostic and Repair Procedures

1. Check Hydraulic Fluid Levels: Ensure that the hydraulic fluid is at the correct level and free from contaminants. Low or dirty fluid can impair the system's performance.
   
2. Bleed the Hydraulic System: If air is suspected in the hydraulic lines, bleeding the system can help restore proper function. This involves opening the bleed screws and allowing the air to escape while the engine is running at idle.
   
3. Inspect Steering Clutches: If hydraulic issues are ruled out, inspect the steering clutches for wear or damage. This may require removing the clutch packs and examining them for signs of wear or contamination.
   
4. Examine Linkages: Check the mechanical linkages for any signs of wear, damage, or disconnection. Adjust or replace components as necessary to ensure proper engagement of the steering clutches.
   

Preventive Maintenance Tips

• Regular Fluid Checks: Regularly monitor hydraulic fluid levels and quality to prevent issues related to contamination or low fluid levels.
  
• Routine Inspections: Conduct periodic inspections of the steering system components, including clutches, linkages, and hydraulic lines, to identify and address potential problems early.
  
• Proper Operation: Avoid abrupt maneuvers that can strain the steering system, and ensure that the machine is operated within its design specifications.
  

Conclusion
Steering issues in the Caterpillar 955L track loader can stem from various sources, including hydraulic system problems, steering clutch failures, and mechanical linkages. By systematically diagnosing the issue and performing the necessary repairs, operators can restore the loader's steering functionality. Regular maintenance and attentive operation are key to prolonging the life of the steering system and ensuring the loader's reliability on the job site.