Case 850G Dozer Right Track Inoperative: Causes, Diagnostics, and Solutions

[MikePhua]

Introduction to the Case 850G Track Problem
The Case 850G dozer is a powerful machine widely used in earthmoving and construction. However, one common issue reported is the failure of the right track to operate, which severely limits the machine’s maneuverability and productivity. Understanding the root causes and the troubleshooting steps for this problem is crucial for operators and technicians to restore full functionality efficiently.

Understanding the Track Drive System
The right and left tracks of the Case 850G are powered independently by hydrostatic drive motors connected to the final drives. The key components involved include:

• Hydraulic Drive Motor: Converts hydraulic energy into mechanical torque to turn the sprocket.
  
• Final Drive Assembly: Contains gears that transfer torque from the motor to the track.
  
• Hydraulic Lines and Valves: Control the flow and pressure of hydraulic fluid to the drive motor.
  
• Control Levers and Linkages: Allow the operator to command track movement.
  

Any failure within these components or their control systems can cause one track to become inoperative.

Common Causes of Right Track Inoperability

• Hydraulic Motor Failure: The drive motor for the right track may suffer internal damage such as worn bearings, seals, or gear teeth, resulting in loss of torque.
  
• Hydraulic Fluid Issues: Low hydraulic fluid levels, contamination, or air in the system can reduce pressure and flow, disabling the right track.
  
• Control Valve Malfunction: The directional control valve that directs fluid to the right track motor might be stuck, damaged, or leaking internally.
  
• Hydraulic Hose or Line Damage: Cracks, leaks, or blockages in hoses supplying the right track motor cause loss of hydraulic pressure.
  
• Electrical or Sensor Failures: Some Case 850G models have electronic sensors or control modules influencing track drive; faults here can prevent track engagement.
  
• Mechanical Final Drive Problems: Gear damage, bearing failure, or sprocket wear in the final drive can mechanically prevent the track from moving.
  

Diagnostic Procedures
Effective diagnosis involves systematic inspection of hydraulic and mechanical systems:

• Visual Inspection: Check for obvious hydraulic leaks, damaged hoses, and external damage on the right track motor and final drive.
  
• Hydraulic Pressure Testing: Measure pressure at the right track motor inlet to verify adequate hydraulic power delivery.
  
• Control Valve Operation Check: Test the valve’s function by operating control levers and observing response or manually cycling the valve.
  
• Hydraulic Fluid Analysis: Inspect fluid condition for contamination or air bubbles.
  
• Mechanical Inspection: Remove and inspect the final drive and motor for internal wear or damage.
  
• Electronic Diagnostics: Use diagnostic tools to scan for error codes or sensor faults if applicable.
  

Repair and Maintenance Recommendations

• Hydraulic Motor Repair or Replacement: If internal damage is found, rebuilding or replacing the motor is necessary.
  
• Control Valve Service: Cleaning, repairing, or replacing faulty valves ensures proper fluid direction.
  
• Hydraulic Hose Replacement: Replace any cracked or leaking hoses with new, properly rated hydraulic lines.
  
• Fluid Flush and Replacement: Regular hydraulic fluid changes prevent contamination-related issues.
  
• Final Drive Overhaul: Repair worn or damaged gears, bearings, and sprockets to restore mechanical function.
  
• Electrical Repairs: Address any wiring or sensor faults with professional diagnostic and repair tools.
  

Terminology Glossary

• Hydrostatic Drive: A transmission system where hydraulic fluid powers motors to drive the tracks.
  
• Directional Control Valve: A valve that directs hydraulic fluid flow to control motor direction.
  
• Final Drive: The gear assembly transmitting torque from the motor to the track sprocket.
  
• Torque: Rotational force applied to move the track.
  
• Hydraulic Contamination: Presence of dirt or air bubbles in the hydraulic fluid, reducing efficiency.
  

Case Examples and Insights
In one real-world instance, a Case 850G experienced right track failure due to a cracked hydraulic hose near the motor. The operator noticed a sudden drop in track speed and fluid leakage. After replacing the hose and bleeding the system, the track restored full operation, illustrating the importance of routine hose inspections.
Another technician encountered internal valve spool damage causing intermittent right track engagement. After replacing the control valve, smooth track operation returned, preventing potential costly damage from continued use.

Preventive Maintenance Tips

• Conduct regular inspections of hydraulic hoses and fittings for wear or leaks.
  
• Monitor hydraulic fluid levels and quality, changing fluid and filters as recommended.
  
• Lubricate and service final drives periodically to prevent mechanical failures.
  
• Use manufacturer-approved parts for repairs to ensure reliability.
  
• Train operators to report early signs of track problems like sluggishness or unusual noises.
  

Summary of Key Points

• The Case 850G right track can become inoperative due to hydraulic motor, valve, hose, fluid, or mechanical final drive issues.
  
• Thorough diagnostic steps include visual inspection, pressure testing, valve checks, fluid analysis, and mechanical examination.
  
• Repairs may involve hydraulic motor overhaul, valve servicing, hose replacement, and final drive repairs.
  
• Proper maintenance and early detection of issues can prevent severe failures.
  
• Real-world cases demonstrate the variety of causes and the importance of detailed troubleshooting.
  

Conclusion
The inoperability of the right track on a Case 850G dozer poses significant operational challenges but can be effectively resolved through methodical diagnostics and targeted repairs. Understanding the hydraulic and mechanical systems involved empowers technicians and operators to quickly identify root causes. By following maintenance best practices and responding promptly to early warning signs, the longevity and performance of the dozer can be preserved, ensuring dependable service on demanding job sites worldwide.