Resolving Jerky Track Control on the 1997 John Deere 690E LC

[MikePhua]

The Evolution of the 690E LC Excavator
The John Deere 690E LC excavator was introduced in the mid-1990s as part of Deere’s E-Series lineup, which emphasized hydraulic refinement, operator comfort, and electronic control integration. Built for mid-size excavation tasks, the 690E LC featured a long carriage (LC) undercarriage for improved stability and digging reach. Powered by the 6068T turbocharged diesel engine delivering around 135 horsepower, the machine was designed to handle trenching, site prep, and utility work with precision.
By the late 1990s, John Deere had sold thousands of E-Series excavators globally, with the 690E LC becoming a staple in municipal fleets and contractor yards. Its hydraulic system, built around Linde components and Deere’s proprietary control logic, was praised for responsiveness—but also known to be sensitive to wear and calibration issues over time.
Symptoms of Jerky Track Movement
Operators of aging 690E LC units have reported a specific issue: overly sensitive or jerky track control, especially when transitioning from creep speed to full travel. The symptoms include:

• Abrupt lurching when engaging travel levers or pedals
  
• Smooth movement only at full lever engagement
  
• Amplified jerking due to operator overcorrection
  
• Less severe behavior in reverse travel
  
• Engine bogging when attempting slow forward movement
  

These symptoms suggest a mismatch between pilot pressure modulation, hydraulic flow control, and engine load response. In some cases, the issue is exacerbated by throttle control malfunctions or bypassed electronic systems.
Root Causes and Diagnostic Pathways
Several factors can contribute to jerky track control:
Pilot Pressure Instability

• Air trapped in pilot lines can cause erratic valve response
  
• Worn pilot control valves may fail to modulate pressure smoothly
  
• Solution: Bleed pilot circuits and inspect pilot valve seals
  

Electronic Throttle Control Failure

• The original electronic throttle actuator may leak or fail
  
• Bypass switches used to override throttle logic can disrupt hydraulic coordination
  
• Solution: Restore proper throttle control or install a mechanical cable conversion with calibrated stops
  

Hydraulic Pump Response Lag

• Linde hydraulic pumps rely on load-sensing feedback to adjust flow
  
• If sensors or actuators are disconnected, the pump may overreact to small inputs
  
• Solution: Verify pump control wiring and recalibrate flow response settings
  

Travel Mode Selector Malfunction

• The 690E LC includes a travel speed selector (tortoise/hare mode)
  
• If the controller is bypassed or non-functional, mode changes may not affect behavior
  
• Solution: Test mode selector switches and confirm controller output
  

Engine Load Management

• If the engine bogs under partial travel input, it may indicate poor fuel delivery or governor response
  
• Solution: Inspect fuel filters, injectors, and governor linkage
  

A technician in Colorado once traced jerky travel to a failed pilot accumulator. The unit had lost nitrogen charge, causing pressure spikes during lever engagement. After replacing the accumulator and bleeding the system, track movement returned to normal.
Throttle Conversion and Its Implications
Many owners of older 690E LC machines have converted the electronic throttle system to a mechanical cable setup. While this restores manual control, it can disrupt the coordination between engine RPM and hydraulic demand. Without proper calibration, the engine may not ramp up quickly enough to match pump output, leading to bogging or jerky movement.
To mitigate this:

• Set idle and full-throttle stops precisely
  
• Use a spring-loaded return to prevent over-revving
  
• Monitor engine RPM during travel and adjust cable tension accordingly
  

Field Anecdotes and Practical Fixes
An operator in British Columbia reported that his 690E LC would lurch violently unless the travel levers were fully engaged. After inspecting the pilot lines, he discovered a cracked hose near the left drive planetary. Replacing the hose and bleeding the system reduced the jerkiness by 80%.
In another case, a contractor in Ohio bypassed the hydraulic throttle actuator due to a persistent leak. He capped the hoses and installed a cable throttle. While this solved the leak, it introduced jerky travel. After adjusting the cable stops and cleaning the fuel system, the machine regained smooth movement.
Preventive Maintenance Recommendations
To maintain smooth track control:

• Bleed pilot and main hydraulic circuits annually
  
• Replace pilot filters every 500 hours
  
• Inspect throttle actuators and mode selectors quarterly
  
• Calibrate travel speed settings after any electrical or hydraulic repair
  
• Monitor engine RPM during travel and adjust throttle linkage as needed
  

Installing a pressure gauge on the pilot circuit can help diagnose erratic behavior early. Some operators retrofit flow restrictors or dampers to the travel control lines to reduce sensitivity.
Conclusion
Jerky track control in the 1997 John Deere 690E LC excavator is often the result of pilot pressure instability, throttle control failure, or hydraulic pump miscommunication. With careful diagnosis, targeted repairs, and calibrated throttle response, operators can restore smooth travel and regain confidence in machine handling. These excavators, built during a transitional era of electronic integration, reward those who understand both mechanical fundamentals and control logic. When tuned properly, the 690E LC remains a capable and responsive tool for excavation tasks across varied terrain.