Safely Removing the Belly Pan on a CAT 963C Track Loader

[MikePhua]

CAT 963C Overview and Belly Pan Configuration
The Caterpillar 963C track loader was introduced in the late 1990s as part of CAT’s C-series upgrade, offering improved hydraulics, operator comfort, and emissions compliance. With an operating weight of approximately 42,000 lbs and powered by a 170 hp CAT 3116 turbocharged diesel engine, the 963C was widely used in construction, demolition, and landfill operations. Its undercarriage includes a segmented belly pan system—typically divided into front, center, and rear guards—designed to protect the drivetrain, hydraulic lines, and fuel tank from debris and impact.
Terminology Note

• Belly Pan: A steel plate or guard mounted under the machine to shield critical components.
  
• Sprung Pan: A belly pan that has warped or bent due to impact or improper removal.
  
• Rattle Gun: A pneumatic impact wrench used to remove stubborn bolts.
  
• Hooks/Catches: Retention features that hold the pan in place even after bolts are removed.
  
• Job Hazard Analysis (JHA): A safety protocol outlining risks and procedures for specific tasks.
  

Time Estimates and Influencing Factors
Removing the belly pan on a 963C can take anywhere from less than an hour to over five hours, depending on several variables:

• Condition of bolts: If bolts are seized, stripped, or damaged by rock impacts, removal time increases significantly.
  
• Debris accumulation: Pans filled with hardened mud or gravel may weigh over 500 lbs and resist movement.
  
• Work environment: Cold weather, uneven ground, or lack of air tools can slow progress.
  
• Manpower and tooling: A single mechanic working carefully may take 2–3 hours, while a team with proper jacks and impact tools can finish in under 90 minutes.
  
• Safety precautions: Using chains, jacks, and crane support adds time but is essential to prevent injury.
  

In Alaska, a technician reported that sub-zero temperatures caused tools to freeze and gloves to stiffen, extending the job well beyond expectations. In Pennsylvania, a mechanic recalled a fatal accident involving a D10 belly pan, prompting a complete rewrite of the company’s JHA for skid plate removal.
Recommended Procedure and Safety Measures

• Preparation
  • Park on level ground, preferably concrete.
    
  • Use a floor jack or crane to support the pan.
    
  • Run a safety chain under the pan and anchor to the opposite track.
    
• Bolt Removal
  • Use a 3/4" impact wrench with extensions.
    
  • Grind damaged bolt heads if sockets won’t seat.
    
  • Apply penetrating oil and allow time to soak.
    
• Lowering the Pan
  • Place wood blocks (e.g., 6x6) under each end.
    
  • Slowly lower the jack and drive the machine forward.
    
  • Avoid standing under the pan at any time.
    
• Reinstallation Tips
  

• Apply anti-seize compound to all bolts.
  
• Use alignment bars and multiple jacks for warped pans.
  
• Replace missing hooks or catches to prevent future sagging.
  

Common Challenges and Field Solutions

• Sprung pans often require hydraulic jacks and brute force to realign.
  
• Frozen bolts may need torch heating or bolt extractors.
  
• Debris-packed pans should be cleaned before removal to reduce weight.
  
• Owner impatience can pressure mechanics into unsafe shortcuts—clear communication is key.
  

In North Dakota, a farmer removed both rear doors on a 973C in 2.5 hours using air tools and a floor jack. In Oklahoma, a mechanic emphasized the importance of chaining pans before removal, having been hit in the shoulder multiple times by sliding guards.
Conclusion
Removing the belly pan on a CAT 963C is a deceptively complex task that demands preparation, patience, and respect for safety. While experienced crews can complete the job quickly, field conditions, pan deformation, and bolt damage can turn a routine procedure into a multi-hour ordeal. With proper tools, clear protocols, and attention to hazard mitigation, the job can be done efficiently—and without injury.