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The John Deere 850C Crawler Dozer, a mid-sized machine introduced in the late 1990s, is renowned for its durability and versatility in various construction and forestry applications. However, like all heavy machinery, it is not without its challenges. Understanding these common issues and their solutions can help operators maintain optimal performance and extend the machine's lifespan.
1. Transmission and Movement Issues
One of the most frequently reported problems with the 850C is related to its transmission system. Operators have noted instances where the dozer fails to move forward or backward, despite the engine running smoothly. This issue is often accompanied by error codes such as F695, indicating electrical communication problems between the transmission control unit (TCU) and the operator's display.
Potential Causes:
- Faulty speed sensors, particularly the one located near the front hydrostatic pump.
- Corroded or damaged wiring harnesses and connectors.
- Issues with the transmission calibration process.
- Inspect and clean all electrical connections, especially those associated with the speed sensors.
- Replace any faulty speed sensors.
- Perform a complete transmission calibration to reset the system's parameters.
- Consult the service manual for specific diagnostic procedures and wiring diagrams.
The undercarriage of the 850C is subjected to significant wear due to constant contact with the ground. Components such as track rollers, idlers, sprockets, and track shoes can wear out over time, leading to reduced performance and potential mechanical failures.
Signs of Wear:
- Uneven track tension.
- Excessive track sag or tightness.
- Visible damage to track shoes or rollers.
- Regularly inspect the undercarriage components for signs of wear or damage.
- Adjust track tension according to the manufacturer's specifications.
- Replace worn or damaged components promptly to prevent further damage.
Hydraulic system leaks can lead to a loss of power and efficiency in the 850C. Common leak points include hydraulic hoses, fittings, and cylinders.
Identifying Leaks:
- Visible oil stains on the ground or machine components.
- Decreased lifting or pushing power.
- Unusual noises from the hydraulic system.
- Tighten or replace leaking fittings and hoses.
- Inspect hydraulic cylinders for signs of wear or damage.
- Regularly check hydraulic fluid levels and top up as necessary.
Engine performance problems can manifest as reduced power, stalling, or difficulty starting. These issues can be caused by various factors, including fuel system problems, air intake restrictions, or electrical faults.
Troubleshooting Steps:
- Check the fuel system for blockages or contamination.
- Inspect the air filter and intake system for obstructions.
- Test the battery and charging system to ensure proper voltage levels.
- Examine the wiring harness for signs of wear or damage.
Malfunctions in the operator display can hinder the operator's ability to monitor machine performance and diagnose problems. Issues may include blank screens, erratic readings, or complete failure of the display.
Diagnostic Approach:
- Perform a system reset by disconnecting and reconnecting the battery.
- Check for blown fuses or tripped circuit breakers.
- Inspect the wiring connections to the display unit.
- Use diagnostic tools to retrieve any stored error codes.
The John Deere 850C Crawler Dozer is a robust machine capable of handling demanding tasks. Regular maintenance and prompt attention to common issues can ensure its longevity and reliable performance. Operators should familiarize themselves with the machine's systems and consult the service manual for detailed troubleshooting procedures. By addressing problems proactively, the 850C can continue to serve effectively in various applications.
