Steering Clutch Diagnosis and Repair in the Caterpillar 955 Track Loader

[MikePhua]

The 955 and Caterpillar’s Mid-Size Loader Heritage
The Caterpillar 955 track loader was introduced in the mid-20th century as part of CAT’s push to offer versatile, crawler-based loading machines for construction, forestry, and mining. With an operating weight between 25,000 and 30,000 pounds depending on configuration, and powered by a robust diesel engine ranging from 80 to 125 horsepower across variants, the 955 became a staple in fleets across North America and beyond.
Caterpillar’s track loaders were designed to combine the digging power of a dozer with the material-handling capability of a front-end loader. The 955, particularly the 955L and 955K models, featured mechanical steering clutches and brake bands that allowed independent control of each track—critical for maneuvering in tight spaces and uneven terrain.
Understanding Steering Clutch Functionality
The steering clutches in the 955 are mechanical assemblies located on each side of the final drive. Their purpose is to disengage power from one track while allowing the other to continue driving, enabling the machine to turn. Each clutch is paired with a brake band that stops the disengaged track, allowing sharper turns.
Terminology Note: “Steering clutch” refers to a multi-disc friction pack that transmits torque from the transmission to the final drive. “Brake band” is a curved friction strip that wraps around a drum to stop rotation when engaged.
Symptoms of clutch failure include:

• Difficulty turning in one direction
  
• Machine pulls to one side under load
  
• Steering lever feels loose or offers no resistance
  
• Audible grinding or slipping during turns
  
• Reduced braking effectiveness on one side
  

In 2023, a forestry crew in Oregon noticed their 955K drifting left during log loading. Inspection revealed worn clutch discs and a cracked brake band on the right side, likely caused by years of operation in abrasive soil.
Disassembly and Inspection Strategy
Accessing the steering clutches requires removing the track and final drive cover. Steps include:

• Park machine on level surface and block tracks
  
• Remove track pads and loosen track tension
  
• Unbolt final drive cover and drain oil
  
• Extract clutch pack and brake band assembly
  
• Inspect discs for glazing, warping, or wear
  
• Check springs and pressure plates for fatigue
  
• Examine brake band lining and drum surface
  

Recommended tools:

• Torque wrench and breaker bar
  
• Clutch spring compressor
  
• Dial indicator for measuring disc thickness
  
• Brake band spreader
  
• Magnetic pickup tool for retaining clips
  

A technician in Alberta rebuilt both steering clutches on a 955L using aftermarket friction discs and new springs. The job took two days and restored full steering control, even under heavy load.
Common Failure Points and Preventive Measures
Steering clutch issues often stem from:

• Oil contamination from leaking seals
  
• Overheating due to aggressive turning or poor ventilation
  
• Misadjusted linkage causing partial engagement
  
• Worn brake band linings reducing stopping power
  
• Rust and corrosion from long-term storage
  

Preventive strategies:

• Replace input shaft seals during clutch service
  
• Use correct oil type and maintain fluid levels
  
• Adjust steering linkage to factory specs
  
• Clean clutch housing and inspect for debris
  
• Operate machine with smooth, deliberate turns
  

In 2022, a contractor in Texas added inspection ports to his 955K’s clutch housing. The modification allowed visual checks of disc condition without full disassembly, reducing downtime and improving maintenance scheduling.
Parts Sourcing and Restoration Advice
Finding parts for the 955 can be challenging due to its age. Options include:

• Salvage yards specializing in vintage CAT equipment
  
• Aftermarket suppliers offering reproduction clutch discs and brake bands
  
• Custom fabrication of linkage components and springs
  
• Rebuilding original parts using friction material and machine shop services
  

Recommendations:

• Cross-reference part numbers with older CAT manuals
  
• Use high-quality friction material rated for heavy-duty use
  
• Replace both sides simultaneously to maintain balance
  
• Document all measurements and torque specs for future reference
  

A restorer in Pennsylvania rebuilt his 955H using clutch discs from a D6 dozer. With minor machining, the parts fit perfectly and restored full steering function.
Operator Tips and Field Adjustments
To maintain steering performance in the field:

• Avoid sharp turns under full load
  
• Use both levers evenly to prevent asymmetric wear
  
• Monitor for changes in lever feel or response
  
• Keep clutch housing clean and dry
  
• Perform brake band adjustment every 500 hours
  

Field kit essentials:

• Spare clutch discs and brake band lining
  
• Linkage bushings and retaining clips
  
• Grease gun and torque chart
  
• Inspection mirror and flashlight
  
• Laminated clutch diagram for reference
  

In 2024, a municipal crew in Maine created a clutch adjustment checklist for all operators. The checklist reduced steering complaints and extended clutch life across the fleet.
Conclusion
Steering clutch maintenance in the Caterpillar 955 is essential for safe and efficient operation. With proper diagnosis, careful disassembly, and quality parts, these machines can continue to perform reliably even decades after production. Whether clearing land, loading gravel, or grading slopes, the ability to steer with precision defines the 955’s legacy. In crawler loaders, control isn’t just mechanical—it’s the heartbeat of productivity.