Case 850 Dozer Maintenance and Field Repair Insights

[MikePhua]

The Development of the Case 850 Series
The Case 850 crawler dozer was introduced in the 1970s by Case Construction Equipment, a division of the J.I. Case Company founded in 1842. By the time the 850 series rolled out, Case had already established itself as a major force in compact and mid-size earthmoving equipment. The 850 was designed to compete with Caterpillar’s D4 and D5 models, offering a balance of maneuverability, power, and ease of service.
The 850 featured a torque converter transmission, mechanical steering clutches, and a range of blade configurations including 4-way, 6-way, and in rare cases, 8-way blades. Its operating weight hovered around 17,000 pounds, and it was powered by a Case diesel engine producing approximately 70 horsepower. Thousands of units were sold across North America, particularly to farmers, municipalities, and small contractors.
Blade Pivot Repair and Spherical Bearing Solutions
One common issue with aging Case 850s is wear in the spherical pivot bearing that connects the blade to the lift frame. This bearing allows the blade to tilt and rotate smoothly, but over time, the bore housing can become egg-shaped due to stress and poor lubrication.
Terminology:

• Spherical Bearing: A ball-shaped bearing that accommodates angular misalignment between connected parts.
  
• Bore Housing: The cylindrical cavity where the bearing is seated.
  
• Snap Ring: A retaining ring used to hold components in place within a bore.
  

In one field repair, a user discovered that the bore had been previously welded—possibly to hold a loose bearing race. To restore functionality, they proposed machining a stepped sleeve with a snap ring groove and welding it into the bore. This would allow future servicing without repeated welding and preserve alignment.
Recommended steps:

• Measure the bore diameter and determine the extent of deformation.
  
• Machine a steel sleeve with a lower step to seat the bearing and an upper lip for snap ring retention.
  
• Grind the bore to accept the sleeve and weld it in place using low-heat passes to avoid warping.
  
• Install the bearing with anti-seize compound and verify blade articulation.
  

Transmission Fluid and Clutch Compatibility
The Case 850 uses wet clutches in its torque converter and transmission system. A critical maintenance point is the use of correct fluid—Case TCH (Transmission, Converter, Hydraulic) oil. Substituting with Hy-Tran or universal hydraulic fluid can degrade clutch linings and lead to expensive rebuilds.
Fluid capacities:

• Engine Oil: 2.5 gallons (recommended: 15W-40 diesel-rated oil)
  
• Hydraulic System: 12 gallons (acceptable: universal hydraulic fluid)
  
• Transmission and Torque Converter: 8 gallons (must use Case TCH)
  
• Final Drives: 1 gallon each (recommended: SAE 80W-90 gear oil)
  

To check torque converter fluid, use the transmission dipstick. The converter and transmission share a fill tube and are connected via a hose, allowing simultaneous level checks.
Brake Behavior and Hill Operation Techniques
The Case 850 features a unique brake system with a selector knob that determines whether braking cuts power to the tracks. On hills, this can affect drivability. When the knob is set to maintain power during braking, the machine slows without shifting to neutral—useful for controlled descents.
Best practices for shifting on slopes:

• Idle down before changing direction to reduce drivetrain shock.
  
• Use the blade to assist braking when backing downhill.
  
• Avoid abrupt throttle changes; feather the foot throttle for smoother transitions.
  
• Engage brakes only when necessary, as engine deceleration often suffices.
  

Two-Speed Steering and Gear Selection
Unlike older Caterpillar models that rely on stopping one track to turn, the Case 850 uses two-speed steering—both tracks remain powered during turns. This improves maneuverability and reduces wear.
Gear selection:

• First and Third gears are engaged with the lever down.
  
• Second and Fourth gears are engaged with the lever up.
  
• Most field work is done in First and Third for better torque control.
  

Later models like the 850C introduced a console-mounted lever allowing on-the-fly gear changes, a feature appreciated by operators transitioning from older machines.
Preventive Maintenance and Seasonal Preparation
Before heavy seasonal use, it’s essential to change all fluids and filters:

• Replace engine oil and both fuel filters (including inline filters if present).
  
• Clean belly pans and inspect for debris buildup near the torque converter.
  
• Check the torque screen and filter for metal filings.
  
• Inspect coolant system and replace filters if equipped.
  

Suggested upgrades:

• Install a magnetic drain plug in the final drives.
  
• Add a hydraulic fluid sight gauge for quick checks.
  
• Retrofit LED work lights for improved visibility.
  

Field Anecdote from Western Pennsylvania
Two brothers purchased a Case 850 to reclaim farmland and clear brush. Despite its age, the dozer ran well, with new chains and one fresh sprocket. The spherical bearing issue was the only major flaw. Using their shop’s lathe and mill, they fabricated a custom sleeve and restored the blade pivot. After moving several tons of soil, they reported satisfaction with the machine’s performance and planned to continue upgrading it as the weather warmed.
Conclusion
The Case 850 dozer remains a reliable workhorse for landowners and contractors alike. With proper fluids, attention to blade pivot wear, and thoughtful operation on slopes, these machines can deliver decades of service. Whether restoring a worn spherical bearing or navigating gear shifts on a hillside, the 850 rewards mechanical intuition and field ingenuity. Its legacy lives on not just in manuals and part catalogs—but in the hands of those who keep it running.