Installing New Tracks on a John Deere 120: Using Liquid Nitrogen for Master Pin Removal

[MikePhua]

Overview of Track Replacement on the John Deere 120
Track replacement is a common maintenance task for tracked equipment like the John Deere 120 excavator. Over time, tracks wear out due to harsh working conditions, necessitating replacement to maintain traction, stability, and safety. One challenging part of the process is removing and installing the master pin, which secures the track ends together. Innovative techniques can simplify this task and reduce downtime.
The Role of the Master Pin and Challenges in Removal
The master pin acts as a crucial link in the track chain, connecting the two ends and allowing the track to flex around the undercarriage. Removing the master pin can be difficult because it is press-fitted and subjected to heavy loads during operation, often causing it to seize or become stuck.
Traditional removal methods involve using large hydraulic presses, heating, or brute force, which can risk damage to track components or require heavy equipment.
Using Liquid Nitrogen for Master Pin Removal
A notable technique shared by operators involves using liquid nitrogen to facilitate master pin removal. The principle relies on the extreme cold temperature of liquid nitrogen causing the metal track links and pin to contract. This thermal contraction creates a slight clearance, loosening the tight press fit and allowing the pin to be driven out more easily.
This method offers several advantages:

• Minimizes Risk of Damage: Cold contraction avoids the risks associated with heating, such as metal warping or heat damage.
  
• Increases Safety: Reduces the physical force required, lowering the chance of injury or tool failure.
  
• Speeds Up the Process: Efficient pin removal means faster track replacement and reduced equipment downtime.
  

Practical Steps and Safety Precautions
Operators using this method typically follow these steps:

1. Apply liquid nitrogen carefully to the area around the master pin, ensuring even coverage.
   
2. Allow sufficient time for the metal to cool and contract.
   
3. Use appropriate tools like pin punches and hydraulic presses to drive out the pin.
   
4. Handle liquid nitrogen with extreme caution, using personal protective equipment such as gloves and eye protection to prevent cold burns.
   

Stories from the Field
An experienced mechanic shared how, after struggling with a stubborn master pin for hours using traditional methods, the liquid nitrogen technique enabled pin removal in under 20 minutes without damage to the track links. This success encouraged adoption of the method in their maintenance shop, improving overall efficiency.
Another operator recounted initial skepticism but found the approach valuable after witnessing a similar pin removal that preserved the integrity of expensive track components.
Broader Industry Context
While liquid nitrogen use in heavy equipment maintenance is not widespread, it is gaining recognition for specific applications such as bearing removal and shrink-fitting components. This technique exemplifies how borrowing from other industrial sectors can lead to innovative, safer, and more cost-effective solutions in construction equipment maintenance.
Conclusion
Replacing tracks on the John Deere 120 excavator is a critical maintenance operation, with master pin removal often posing a significant challenge. Utilizing liquid nitrogen to contract metal components offers a practical and efficient solution, reducing risk and saving time. As the heavy equipment industry embraces such innovative methods, operators benefit from enhanced safety, reduced repair times, and prolonged equipment life. This fusion of science and hands-on skill continues to drive improvements in machinery upkeep worldwide.