John Deere 850K Dozer: Troubleshooting Movement Issues

[MikePhua]

   


Introduction
The John Deere 850K Crawler Dozer is a powerful machine designed for heavy-duty tasks in construction and mining. However, like any complex piece of machinery, it can encounter issues that hinder its performance. One common problem reported by operators is when the engine runs, but the dozer won't move. This article delves into potential causes and solutions for this issue.
Understanding the 850K Dozer
The John Deere 850K is a mid-sized crawler dozer equipped with a 205 horsepower engine. It features advanced hydraulics and transmission systems to provide optimal performance in various terrains. The machine's design emphasizes durability and efficiency, making it a popular choice among contractors.
Potential Causes for Lack of Movement

1. Transmission Issues
   The transmission system is crucial for transferring engine power to the tracks. If the dozer starts but doesn't move, the transmission could be the culprit. Common problems include:
   • Low or Contaminated Fluid: Insufficient or dirty transmission fluid can impede the system's function.
     
   • Faulty Charge Pump: A malfunctioning charge pump may fail to maintain adequate pressure, leading to movement issues.
     
   • Clutch Problems: Worn or damaged clutches can prevent proper engagement.
     
2. Hydraulic System Failures
   The hydraulic system powers various functions, including steering and blade operations. A failure here can also affect movement. Potential causes are:
   • Relief Valve Malfunction: A sticking or partially open relief valve can limit hydraulic pressure, affecting performance.
     
   • Hydraulic Fluid Issues: Low or contaminated fluid can reduce system efficiency.
     
3. Electrical and Sensor Problems
   Modern dozers like the 850K rely on electronic systems for operation. Issues such as:
   • Faulty Sensors: Malfunctioning sensors can send incorrect signals, disrupting operations.
     
   • Wiring Issues: Damaged or corroded wires can interrupt communication between components.
     
4. Final Drive Concerns
   The final drive transfers power from the transmission to the tracks. Problems here can prevent movement, including:
   • Gear Damage: Worn or broken gears can disrupt power transfer.
     
   • Lubrication Failures: Inadequate lubrication can lead to overheating and damage.
     

Diagnostic Steps
To identify the root cause:

• Check Fluid Levels: Ensure that both transmission and hydraulic fluids are at proper levels and free from contamination.
  
• Inspect Filters: Clogged filters can restrict fluid flow, leading to performance issues.
  
• Test Pressure Levels: Use a pressure gauge to verify that the system maintains appropriate pressures.
  
• Examine Electrical Connections: Look for loose or corroded connections that might affect sensor readings.
  
• Listen for Unusual Noises: Strange sounds can indicate mechanical issues within the final drive or transmission.
  

Maintenance Tips
Regular maintenance can prevent many issues:

• Fluid Changes: Regularly replace transmission and hydraulic fluids as per the manufacturer's recommendations.
  
• Filter Replacements: Change filters to ensure clean fluid circulation.
  
• Component Inspections: Periodically check the final drive, transmission, and hydraulic systems for wear and tear.
  
• Electrical System Checks: Ensure that all sensors and wiring are functioning correctly.
  

Conclusion
Experiencing a situation where the John Deere 850K dozer runs but won't move can be frustrating. By systematically diagnosing potential issues and adhering to regular maintenance practices, operators can resolve these problems and ensure the dozer's optimal performance. Always consult the operator's manual and consider seeking professional assistance when necessary.