Chain Adjustment and Drive System Maintenance in the Case 1845C Skid Steer

[MikePhua]

The Case 1845C and Its Mechanical Legacy
The Case 1845C skid steer loader is one of the most iconic machines in compact construction history. Introduced in the early 1990s by Case Corporation—an American manufacturer with roots dating back to 1842—the 1845C quickly became a favorite among contractors, farmers, and municipalities. With over 60,000 units sold globally, it remains one of the most widely used skid steers in its class.
Powered by a 51-horsepower Cummins 4B diesel engine and equipped with a chain-driven drive system, the 1845C is known for its mechanical simplicity, reliability, and ease of service. Unlike modern hydrostatic machines, the 1845C uses a mechanical chain and sprocket system to transfer power from the hydraulic motors to the wheels, making chain adjustment a critical part of long-term maintenance.
Understanding the Chain Drive System
Each side of the 1845C features a pair of drive chains housed within the loader’s frame. These chains connect the hydraulic drive motor to the front and rear drive sprockets, which in turn rotate the wheels. The system is enclosed in a sealed chaincase filled with gear oil to reduce friction and dissipate heat.
Key components include:

• Drive chains (typically #80 or #100 roller chain)
  
• Front and rear drive sprockets
  
• Chaincase housing and cover
  
• Chain tensioning bolts and locknuts
  
• Chaincase oil fill and drain plugs
  

Proper chain tension ensures smooth power transfer, minimizes wear, and prevents chain slap or derailment. Over time, chains stretch and sprockets wear, requiring periodic adjustment and eventual replacement.
Terminology Notes

• Roller Chain: A series of interconnected links with rollers that engage sprocket teeth to transmit motion.
  
• Sprocket: A toothed wheel that meshes with the chain to transfer torque.
  
• Chaincase: An enclosed compartment that houses the drive chains and lubricating oil.
  
• Chain Slap: Excessive movement or vibration of a loose chain, often causing noise and wear.
  

Chain Adjustment Procedure
Adjusting the chains on a Case 1845C involves accessing the chaincase and modifying the position of the drive sprockets. The process requires precision and patience:

• Park the machine on level ground and ensure all hydraulic pressure is relieved
  
• Remove the chaincase cover using appropriate tools
  
• Inspect chain tension by pressing down on the chain midway between sprockets
  
• Ideal deflection should be approximately 1/2 inch to 3/4 inch
  
• Loosen the locknuts on the tensioning bolts
  
• Turn the adjustment bolts evenly to increase or decrease tension
  
• Re-tighten locknuts and reinstall the cover
  
• Check chaincase oil level and top off with SAE 90 gear oil if needed
  

A contractor in Iowa reported that his 1845C began jerking during turns. After inspecting the chaincase, he found the rear chain had stretched significantly. Adjusting the tension and replacing the oil restored smooth operation.
Signs of Chain Wear and Failure
Operators should monitor for the following symptoms:

• Clunking or rattling noises from the chaincase
  
• Uneven drive response or hesitation during turns
  
• Visible chain elongation or side wear
  
• Oil leaks from the chaincase cover
  
• Metal shavings in the chaincase oil
  

If chains are excessively worn, replacement is necessary. Always replace both chains on the affected side to maintain balance and prevent uneven wear. Sprockets should also be inspected for tooth rounding or pitting.
Preventive Maintenance Recommendations
To extend the life of the chain drive system:

• Check chain tension every 250 hours
  
• Change chaincase oil every 500 hours or annually
  
• Use high-quality gear oil with anti-wear additives
  
• Avoid sudden directional changes under load
  
• Keep chaincase seals clean and intact
  

A fleet manager in British Columbia implemented a quarterly inspection schedule for all 1845C units. This reduced chain failures by 60% and improved overall drivability.
Upgrades and Retrofit Options
While the 1845C is mechanically robust, some owners opt for upgrades:

• Install aftermarket chain tension indicators for quick visual checks
  
• Replace chaincase bolts with stainless steel hardware to prevent corrosion
  
• Add magnetic drain plugs to capture metal debris
  
• Use sealed chains for longer service intervals
  

In Texas, a rental company retrofitted its 1845C fleet with upgraded chaincase covers featuring inspection ports. This allowed technicians to check tension without full disassembly, saving hours of labor annually.
Operator Anecdotes and Field Wisdom
A retired operator in Georgia recalled using a Case 1845C for fence post installation. He emphasized the importance of chain tension, noting that loose chains once caused a wheel to lock mid-turn, nearly tipping the machine. After adjusting the tension and replacing worn sprockets, the loader ran flawlessly for another 2,000 hours.
In Alberta, a snow removal crew used their 1845C in sub-zero conditions. They switched to synthetic gear oil in the chaincase to improve cold-start performance and reduce wear during winter operations.
Conclusion
The Case 1845C’s chain-driven system is a testament to mechanical durability and straightforward engineering. Proper chain adjustment is essential for maintaining drivability, safety, and long-term performance. With regular inspections, quality parts, and a bit of operator intuition, this classic skid steer continues to deliver reliable service across job sites, farms, and municipal yards.