Detailed Guide to Removing the Track Motor on the Caterpillar 21Z-963 Track Loader: Procedure, Tips, and Practical Advice

[MikePhua]

Introduction: Understanding the Track Motor in the 21Z-963
The track motor on the Caterpillar 21Z-963 track loader is a critical hydraulic component that drives the tracks, enabling precise and powerful movement. These motors are bent-axis type, high-torque devices connected via splines to the final drive system. Removing the track motor is an essential task during maintenance, repair, or replacement, especially if the motor becomes worn, damaged, or stuck.
This guide provides a detailed, step-by-step approach to removing the track motor from the 21Z-963 track loader, enriched with practical suggestions, troubleshooting advice, terminology explanations, and case experiences to aid technicians and operators.

Preparation and Safety Considerations

• Park the machine on a firm, level surface, engage the parking brake, and shut down the engine.
  
• Relieve hydraulic pressure in the drive system to prevent fluid spray or component damage.
  
• Drain hydraulic oil from the relevant circuits to avoid spills during disconnection.
  
• Clean the area around the track motor to reduce contamination ingress during disassembly.
  
• Have appropriate tools ready, including pry bars, wrenches, lifting chains or hoists, and seal replacement kits.
  
• Use proper personal protective equipment (PPE) including gloves, eye protection, and safety footwear.
  

Step-by-Step Track Motor Removal Procedure

1. Disconnect Hydraulic Lines from the Track Motor
   • Loosen and remove the hydraulic hoses attached to the motor ports.
     
   • Cap or plug hoses and fittings immediately to prevent dirt ingress and hydraulic fluid leakage.
     
2. Remove Pilot Line Connections
   • Detach any pilot pressure lines connected to the motor for controlling braking functions.
     
3. Remove Retaining Hardware
   • Find and remove bolts or nuts securing the track motor to the final drive housing. These fasteners generally hold the motor flange or adapter in place.
     
4. Free Motor from Splines
   • The motor is splined onto the final drive shaft, often making removal difficult due to corrosion or binding.
     
   • Use a suitable pry bar carefully inserted between the motor flange and final drive housing to apply even, gradual force.
     
   • Avoid using excessive force or hammering directly on the motor body to prevent damage.
     
5. Address Stuck or Bound Motor
   • If the motor remains stuck on the splines, apply penetrating lubricants around the spline connection and allow time to soak.
     
   • Reattempt prying with gradual alternating force distribution.
     
   • Using heat (such as a torch) around the motor mounting flange cautiously can expand metal parts differentially, easing removal (do not heat seals or rubber components).
     
   • In severe cases, professional hydraulic or mechanical pullers designed for spline extraction may be necessary.
     
6. Carefully Lift the Motor Away
   • Once loose, use lifting gear such as chains attached to designated lifting points on the motor for safe removal.
     
   • Slowly slide the motor off the splined shaft, avoiding tilt or side loading to prevent shaft or seal damage.
     
7. Inspect Removed Motor and Related Components
   • Check the motor splines and final drive splines for damage or wear.
     
   • Inspect shaft seals, bearings, and mounting surfaces.
     
   • Prepare for seal replacement or housing cleaning as necessary before reinstallation.
     

Practical Tips and Additional Advice

• Avoid Excessive Pry Bar Force: Repeated heavy prying risks distorting motor housing and splines. Apply penetrating oil and be patient.
  
• Cleanliness is Critical: Prevent dirt and debris entering hydraulic passages or seals during disassembly.
  
• Seal Kit and Parts Ready: Have a comprehensive seal kit available to replace all hydraulic and shaft seals during reassembly.
  
• Document Disassembly: Photograph components and take notes to aid in correct reinstallation and torque specifications.
  
• Consult Service Manuals: Reference Caterpillar’s official service manuals for torque specs, seal part numbers, and hydraulic line routing.
  
• Hydraulic Oil Management: Plan for hydraulic fluid flushing or replacement after motor removal to maintain system cleanliness.
  

Terminology Explained

• Track Motor: The hydraulic motor driving the track sprocket through a splined shaft.
  
• Splines: Grooved shaft sections that provide a secure, rotational interlock between components.
  
• Final Drive: The assembly transmitting motor output to the track’s sprocket and tracks itself.
  
• Pilot Line: Hydraulic line supplying low-pressure fluid for brake or control functions on the motor.
  
• Penetrating Oil: Lubricant designed to seep into narrow gaps to loosen rusted or corroded parts.
  
• Hydraulic Seal Kit: A set of replacement seals for preventing leakage around hydraulic components.
  

Case Story: Overcoming a Stuck Track Motor on a 21Z-963
A technician working on a Caterpillar 21Z-963 track loader experienced difficulty removing the right track motor as it was firmly wedged onto the final drive splines. After disconnecting hydraulic lines and removing mounting bolts, the motor refused to budge despite hours of prying.
The technician applied a professional-grade penetrating lubricant and carefully heated the motor mounting flange with a propane torch, avoiding the seal areas. After repeated gentle prying and patience, the motor loosened enough to be lifted safely with a chain hoist.
Post-removal inspection revealed minor spline corrosion and a worn shaft seal, which was replaced during reassembly. The incident underscored the importance of avoiding rush or brute force, emphasizing a methodical approach using lubrication, heat, and proper tools.

Summary Checklist for 21Z-963 Track Motor Removal

• Park safely and relieve hydraulic pressure
  
• Drain relevant hydraulic oil circuits
  
• Disconnect all hydraulic and pilot lines; cap openings
  
• Remove motor mounting bolts securely
  
• Apply penetrating oil and patiently pry motor from splines
  
• Use cautious heat application if necessary
  
• Lift motor using chains or hoist; avoid mechanical damage
  
• Inspect splines, seals, and mounting surfaces
  
• Prepare new seals and clean components for reinstallation
  
• Consult official service guides for torque and procedures
  

Conclusion
Removing the track motor from a Caterpillar 21Z-963 track loader demands careful preparation, appropriate tools, and stepwise execution to avoid damage to expensive hydraulic components and final drive parts. Patience and methodical approaches—leveraging penetrating lubricants, cautious heating, and proper lifting techniques—are essential when faced with stubborn, stuck motors.
Maintaining cleanliness, inspecting seals, and planning hydraulic fluid management further ensure a smooth removal and reinstallation process. Real-world experiences highlight the value of combining practical field methods with official service manual guidance to resolve challenges confidently and efficiently.
This detailed overview offers a comprehensive, easy-to-follow resource for technicians undertaking track motor removal on the Caterpillar 21Z-963, ultimately helping reduce downtime and increase machine reliability.