Diagnosing Steering Issues on the Caterpillar 931 Track Loader

[MikePhua]

The CAT 931 and Its Mechanical Steering System
The Caterpillar 931 track loader was introduced in the 1970s as a compact, versatile machine for grading, loading, and site preparation. With an operating weight around 16,000 pounds and powered by a 70–80 HP diesel engine depending on variant, the 931 was designed to bridge the gap between small dozers and full-size loaders. Its mechanical simplicity and rugged undercarriage made it a favorite among contractors and landowners.
Unlike hydrostatic loaders, the 931 uses a clutch-brake steering system. Each track is controlled by a steering clutch and a corresponding brake. Pulling the clutch lever disengages drive to that track, while pressing the brake slows or stops it, allowing the machine to pivot. This system is reliable but prone to wear if not maintained properly.
Terminology Annotation

• Steering Clutch: A friction-based assembly that disengages power to one track when actuated.
  
• Brake Band: A curved friction surface that wraps around a drum to slow or stop rotation.
  
• Linkage Rod: A mechanical connection between the operator’s lever and the clutch or brake assembly.
  
• Final Drive: The gear assembly that transmits torque from the transmission to the tracks.
  

Common Symptoms of Steering Failure
Operators may encounter the following issues:

• One track fails to disengage when pulling the clutch lever.
  
• Brake pedal feels soft or ineffective.
  
• Machine turns poorly or not at all in one direction.
  
• Audible grinding or squealing during steering.
  

In one case from a logging site in Oregon, a 931 refused to turn left despite full clutch and brake input. The issue was traced to a seized clutch pack and worn brake band, both of which had absorbed water and debris over time.
Initial Inspection and Access Strategy
Before disassembly:

• Park the machine on level ground and block the tracks.
  
• Remove the seat and floor panels to access the steering clutch compartments.
  
• Inspect linkage rods for free movement and proper adjustment.
  
• Check brake pedal travel and spring tension.
  

If the clutch lever moves freely but the track remains engaged, the clutch pack may be stuck or the linkage disconnected. If the brake pedal bottoms out with little resistance, the brake band may be worn or the anchor pin broken.
Disassembly and Component Evaluation
To inspect the clutch and brake assemblies:

• Drain final drive oil to prevent contamination.
  
• Remove the clutch housing cover and inspect the clutch pack.
  
• Check for rust, oil contamination, and broken springs.
  
• Inspect the brake band for glazing, cracking, or uneven wear.
  
• Verify that the anchor pin is intact and seated properly.
  

Use feeler gauges to measure clutch disc thickness and brake band clearance. Compare against factory specifications—typically 0.125–0.150 inches for clutch discs and 0.030–0.050 inches for brake band clearance.
Common Failure Points and Solutions

• Stuck Clutch Pack: Caused by rust or oil contamination. Disassemble and clean thoroughly. Replace discs if warped or worn.
  
• Worn Brake Band: Replace with OEM or aftermarket equivalent. Ensure proper curvature and anchor pin fit.
  
• Broken Linkage Rods: Fabricate replacements or source from salvage yards. Adjust for equal travel on both sides.
  
• Oil-Soaked Friction Material: Replace contaminated parts and inspect seals. Use dry-type friction materials for longevity.
  

A technician in Alberta reported that switching to Kevlar-lined brake bands improved performance and reduced wear in muddy conditions.
Reassembly and Adjustment Tips
During reassembly:

• Torque clutch bolts evenly to avoid warping.
  
• Adjust linkage rods to ensure full clutch disengagement.
  
• Set brake band clearance using manufacturer specs.
  
• Test lever and pedal response before closing covers.
  

Cycle the machine slowly and verify steering response in both directions. Listen for abnormal noises and check for leaks around the clutch housing.
Preventive Maintenance and Longevity
To extend steering system life:

• Inspect clutch and brake assemblies every 500 hours.
  
• Keep compartments clean and dry—moisture accelerates wear.
  
• Lubricate linkage rods and pivot points monthly.
  
• Avoid aggressive steering maneuvers that strain components.
  

In dusty environments, consider installing auxiliary seals or shields to protect the clutch housing from debris ingress.
Recommendations for Operators and Technicians

• Keep spare clutch discs, brake bands, and linkage hardware in stock.
  
• Document service intervals and component replacements.
  
• Train operators to recognize early signs of steering wear.
  
• Use borescope inspection for internal checks without full disassembly.
  
• Partner with rebuild shops for clutch pack resurfacing and band relining.
  

Closing Reflections
The steering system on a Caterpillar 931 is a testament to mechanical simplicity, but it demands respect and maintenance. When clutch packs seize or brake bands wear thin, the machine loses its agility and precision. With careful inspection, targeted repairs, and preventive care, the 931 can continue to maneuver through tight spaces and tough terrain—turning with confidence, one lever pull at a time.