Drive Chain Adjustment and Replacement on the Case 1845C Skid Steer

[MikePhua]

The Case 1845C and Its Mechanical Legacy
The Case 1845C skid steer loader, introduced in the late 1980s and produced through the early 2000s, remains one of the most iconic and widely used compact loaders in North America. With over 60,000 units sold during its production run, the 1845C earned a reputation for mechanical simplicity, reliability, and ease of service. Powered by a 51-horsepower Cummins 4B diesel engine and featuring a chain-driven drive system, the machine was designed to thrive in construction, agriculture, and landscaping environments.
Case Corporation, founded in 1842, had already established itself as a leader in agricultural and construction machinery. The 1845C was part of a broader strategy to dominate the compact equipment market, and its enduring popularity is a testament to its robust design and field-serviceable components.
Understanding the Drive Chain System
The 1845C uses a dual drive chain system to transmit power from the hydraulic motors to the wheels. Each side of the machine has its own chain, tensioned independently. The chains are housed in sealed compartments filled with gear oil, and proper tension is critical to prevent premature wear, noise, and loss of drive efficiency.
Key terminology:

• Drive chain: A roller chain that transmits torque from the hydraulic motor to the drive sprocket.
  
• #60H chain: A heavy-duty ANSI standard roller chain used in the drive system.
  
• #100 chain: A larger pitch chain used in the driven portion of the system.
  
• Chain slack: Excessive looseness in the chain, leading to misalignment and wear.
  
• Adjustment slot: A slotted mounting point allowing the hydraulic motor to be repositioned for chain tensioning.
  

Symptoms of Improper Chain Tension
In one field inspection, the left-hand (LH) drive chain was found to be excessively loose, with no further adjustment available. The right-hand (RH) chain, conversely, was overly tight. This imbalance can lead to uneven wear, increased vibration, and potential chain failure. Operators often describe the issue as a “Goldilocks” scenario—one side too loose, the other too tight.
Common causes include:

• Chain stretch due to age and load cycles
  
• Improper initial installation or adjustment
  
• Worn sprockets causing uneven engagement
  
• Hydraulic motor mounting bolts loosening over time
  

Chain Replacement and Sizing
When adjustment range is exhausted, replacing the chains becomes necessary. The Case 1845C uses #60H chain for the drive motors and #100 chain for the driven components. Chain length varies slightly depending on sprocket wear and motor positioning, so measuring the old chains before ordering replacements is essential.
Replacement steps:

1. Drain gear oil from the chain compartments.
   
2. Remove the access covers and inspect sprockets for wear.
   
3. Disconnect the hydraulic motor and remove the old chain.
   
4. Measure the chain length in links or feet.
   
5. Install new chain and adjust tension using the motor mount slots.
   
6. Refill with gear oil and test for smooth operation.
   

Recommendations:

• Use high-quality ANSI-rated chains with hardened rollers.
  
• Replace both chains simultaneously to maintain balance.
  
• Inspect sprockets and replace if teeth are worn or hooked.
  
• Torque motor mount bolts to spec and apply threadlocker.
  

Preventative Maintenance and Long-Term Reliability
To extend the life of the drive chain system:

• Check chain tension every 250 hours of operation.
  
• Replace gear oil annually or after water intrusion.
  
• Monitor for unusual noise or vibration during operation.
  
• Keep chain compartments sealed and free of debris.
  

In one restoration case, a contractor in Georgia rebuilt the drive system on a 1998 1845C using aftermarket chains and sprockets sourced from a local supplier. After proper installation and adjustment, the machine returned to full service and operated reliably for over 2,000 hours before requiring further attention.
Conclusion
The Case 1845C’s chain-driven system is a hallmark of its mechanical design, offering durability and serviceability in demanding environments. When chain tension becomes unmanageable, replacement is the most effective solution. With proper sizing, installation, and maintenance, the drive chains can deliver thousands of hours of dependable performance. The 1845C continues to earn its place on job sites not just through brute strength, but through the resilience of its engineering.