Chain Case Failures and Brake Pin Damage in the Case 1845C Skid Steer

[MikePhua]

Case 1845C Background and Chain Drive Architecture
The Case 1845C skid steer loader was introduced in the early 1990s and quickly became one of the most popular compact machines in North America. With over 60,000 units sold globally, it remains a workhorse in agriculture, construction, and landscaping. The 1845C features a mechanical chain drive system housed in sealed chain cases on both sides of the machine. Each side contains a drive chain, sprockets, and a cluster sprocket assembly that interfaces with the brake system.
Terminology Note

• Cluster Sprocket: A multi-function sprocket that transmits drive power and interfaces with the brake pin.
  
• Brake Pin: A steel pin that engages with holes in the cluster sprocket to lock the drive system.
  
• Chain Case: A sealed compartment containing the drive chain and sprockets, filled with gear oil.
  
• RVT Sealant: A silicone-based gasket maker used to improve sealing on plastic covers.
  
• Induced Shear Failure: A mechanical break caused by stress concentration, often due to misalignment or improper engagement.
  

Symptoms and Inspection Findings
Operators have reported a rattling noise during high-speed travel, resembling a chain skipping teeth. The issue temporarily disappears when reversing, then returns after a short distance. Upon inspection:

• Water was found in the right chain case, suggesting seal failure.
  
• Metal fragments were discovered in the left chain case, shaped like half-moon slivers approximately 1 inch in diameter.
  
• Chain tension appeared normal, but the source of the noise was unclear.
  
• Brake engagement was suspected, possibly while the machine was in motion.
  

These findings suggest that the brake pin may have engaged improperly or remained partially extended, causing damage to the cluster sprocket.
Root Cause Analysis

• Brake Pin Misalignment or Cable Failure
  If the brake cable is stretched or misrouted, the pin may not fully retract. When the machine moves, the pin can shear off portions of the sprocket holes.
  Solution: Inspect the brake cable for tension and routing. Replace if frayed or stretched.
  
• Water Intrusion Through Inspection Covers
  The plastic chain case covers are prone to leaking, especially if overtightened. Cracks or poor sealing allow water to enter, leading to corrosion and accelerated wear.
  Solution: Use RVT sealant during reinstallation. Avoid overtightening and inspect for cracks.
  
• Metal Shavings from Sprocket Damage
  The half-circle fragments are consistent with brake pin hole damage on the cluster sprocket.
  Solution: Remove the sprocket and inspect the engagement holes. Replace if damaged.
  
• Chain Slack and Sprocket Wear
  Even if tension appears correct, worn sprockets can cause chain jump under load.
  Solution: Measure chain stretch and inspect sprocket teeth for rounding or pitting.
  

Preventive Maintenance Recommendations

• Drain and inspect chain cases every 500 hours
  
• Replace gear oil annually or after water intrusion
  
• Grease wheel bearings behind the tires monthly
  
• Inspect brake pin engagement and cable tension quarterly
  
• Use RVT sealant on chain case covers during service
  

Conclusion
The Case 1845C’s chain drive system is robust but vulnerable to brake pin misalignment and water intrusion. Metal shavings in the gear oil often point to cluster sprocket damage caused by improper brake engagement. By inspecting the brake cable, sealing the chain case properly, and monitoring chain tension, operators can prevent costly failures and extend the life of this iconic skid steer.