Chain Case Fluid and Maintenance Strategy for the New Holland L785 Skid Steer

[MikePhua]

The L785 and Its Mechanical Heritage
The New Holland L785 skid steer loader, produced in the late 1980s and early 1990s, was part of a generation of compact machines built for versatility and mechanical simplicity. With a rated operating capacity of approximately 1,850 lbs and a robust chain-driven drivetrain, the L785 was widely adopted by farmers, landscapers, and small contractors. It featured a mechanical two-speed transmission, manually actuated controls, and a chain case that doubled as a hydraulic reservoir—a design choice that simplified fluid management but required careful attention to compatibility and maintenance.
New Holland, originally founded in Pennsylvania in 1895, became a global brand through its merger with Ford and later CNH Industrial. The L785 was one of its most successful skid steer models of the era, with thousands sold across North America. Its rugged design and straightforward serviceability have kept many units in operation decades later.
Terminology Annotation
- Chain Case: An enclosed compartment housing the drive chains that transfer power from the transmission to the wheels. In the L785, it also serves as the hydraulic fluid reservoir.
- HyTran Fluid: A multi-purpose hydraulic and transmission oil developed by International Harvester, widely used in agricultural and industrial equipment.
- Two-Speed Control Lever: A mechanical selector that allows the operator to switch between low and high travel speeds.
- Fill and Check Port: An access point for adding and inspecting fluid levels, typically located near the operator’s seat or control levers.
Fluid Type and Compatibility
The L785’s chain case requires hydraulic fluid that meets specific anti-wear and viscosity standards. While some newer skid steers use engine oil or synthetic blends, the L785 is best served by HyTran or equivalent AW-46 hydraulic oil. These fluids offer:

• Anti-foaming properties to prevent cavitation
  
• Detergent additives to suspend contaminants
  
• Viscosity stability across temperature ranges
  
• Compatibility with older seal materials
  

Using engine oil or incompatible fluids may lead to seal degradation, reduced lubrication, and premature chain wear. Operators should avoid mixing fluid types and always verify specifications before refilling.
A Story from the Texas Panhandle
A rancher in Cooper, Texas, inherited a 1991 L785 from his uncle and noticed sluggish lift response and chain noise during operation. After inspecting the chain case, he discovered low fluid levels and contamination from water ingress. His local dealer recommended HyTran fluid, and after flushing the system and refilling, the loader returned to full performance. He later installed a breather cap with a desiccant filter to prevent future moisture intrusion.
Fluid Access and Inspection Points
To check and refill the chain case:

• Locate the fill and check port to the right of the operator’s seat, just above the two-speed control lever
  
• Clean the area thoroughly before opening to prevent debris entry
  
• Use a dipstick or sight gauge to verify fluid level
  
• Add fluid slowly to avoid overfilling and allow air to escape
  
• Inspect for leaks around seals and chain tensioners
  

If the machine has been sitting unused or exposed to weather, drain and flush the chain case before refilling. Water contamination can lead to rust, emulsification, and hydraulic failure.
Recommendations for Maintenance and Longevity
To preserve the drivetrain and hydraulic system:

• Change hydraulic fluid every 500 hours or annually, whichever comes first
  
• Use only fluids meeting HyTran or AW-46 specifications
  
• Inspect chain tension monthly and adjust as needed
  
• Replace seals and gaskets during major service intervals
  
• Install magnetic drain plugs to capture metal particles
  
• Keep a maintenance log with fluid type, hours, and service notes
  

For machines operating in dusty or humid environments, consider upgrading to sealed chain case breathers and using fluid analysis kits to monitor contamination levels.
Conclusion
The New Holland L785 skid steer’s chain case serves a dual role as drivetrain housing and hydraulic reservoir, making fluid selection and maintenance critical to performance. HyTran or AW-46 hydraulic oil offers the best balance of protection and compatibility for this legacy machine. With proper inspection, fluid management, and preventative care, the L785 can continue delivering reliable service well beyond its original design life. Its mechanical simplicity remains a testament to an era when durability and field serviceability were paramount.