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The JD 690B and Its Place in Excavator History
The John Deere 690B excavator was introduced in the late 1970s as part of Deere’s second-generation hydraulic excavator lineup. It followed the original 690 model and preceded the 690C, marking a transitional phase in Deere’s evolution from mechanical linkage machines to more refined hydraulic systems. Built during a time when Deere was expanding its construction equipment division aggressively, the 690B was designed for general excavation, trenching, and light demolition.
John Deere, founded in 1837, had by the 1980s become a major player in the construction equipment market. The 690B was manufactured at Deere’s Dubuque Works facility and sold widely across North America. Though exact production numbers are hard to confirm, the 690B was one of Deere’s more popular mid-size excavators, often found in municipal fleets and small contractor yards.
Serial Numbers and Model Variants
Serial numbers on the 690B often include suffixes like “A” or “T,” which can be confusing to new owners. The “A” may indicate a sub-variant or a factory-specific configuration, while the “T” is commonly associated with turbocharged engines.
Terminology:
Engine and Hydraulic System Overview
Most 690B units were powered by the John Deere 6404T diesel engine, a 6.6-liter inline-six producing approximately 110–125 horsepower. The turbocharged version offered better performance at altitude and under heavy load, making it ideal for contractors working in mountainous regions or with demanding attachments.
Hydraulic features included:
Mechanical Controls and Operator Experience
Early 690Bs featured long mechanical control sticks—often referred to as “wobble sticks”—that connected directly to valve linkages. These controls required physical effort and offered little finesse compared to modern pilot-operated joysticks.
However, later serial numbers introduced pilot controls in some units, offering smoother operation and reduced fatigue. This transition was not uniform, and many machines retained mechanical linkages throughout their service life.
Operators from the 1980s recall that running a 690B was a full-body workout. Without cab insulation or ergonomic seating, the machine was loud, hot, and unforgiving. Yet it was also reliable. As one veteran put it, “If it had fuel, fire, and fluids, it worked.”
Common Quirks and Field Observations
Several quirks are common among 690Bs:
Parts Availability and Restoration Tips
While Deere no longer produces parts for the 690B, many components are still available through aftermarket suppliers and salvage yards. The 6404T engine shares parts with other Deere machines, making engine rebuilds feasible.
Restoration tips:
Conclusion
The John Deere 690B excavator is a relic of a bygone era—mechanical, loud, and built to last. While it lacks the finesse and efficiency of modern machines, it remains a viable option for owners willing to invest in maintenance and restoration. With a turbocharged engine, robust hydraulics, and a reputation for reliability, the 690B continues to dig, swing, and lift decades after leaving the factory. Whether grading farmland in North Dakota or trenching in the Pacific Northwest, this machine proves that old iron still has a place in the dirt.
The John Deere 690B excavator was introduced in the late 1970s as part of Deere’s second-generation hydraulic excavator lineup. It followed the original 690 model and preceded the 690C, marking a transitional phase in Deere’s evolution from mechanical linkage machines to more refined hydraulic systems. Built during a time when Deere was expanding its construction equipment division aggressively, the 690B was designed for general excavation, trenching, and light demolition.
John Deere, founded in 1837, had by the 1980s become a major player in the construction equipment market. The 690B was manufactured at Deere’s Dubuque Works facility and sold widely across North America. Though exact production numbers are hard to confirm, the 690B was one of Deere’s more popular mid-size excavators, often found in municipal fleets and small contractor yards.
Serial Numbers and Model Variants
Serial numbers on the 690B often include suffixes like “A” or “T,” which can be confusing to new owners. The “A” may indicate a sub-variant or a factory-specific configuration, while the “T” is commonly associated with turbocharged engines.
Terminology:
- Serial Number Suffix: Letters appended to the model number to denote factory options, engine type, or production batch.
- Turbocharged Engine: An engine fitted with a turbocharger to increase power output by forcing more air into the combustion chamber.
Engine and Hydraulic System Overview
Most 690B units were powered by the John Deere 6404T diesel engine, a 6.6-liter inline-six producing approximately 110–125 horsepower. The turbocharged version offered better performance at altitude and under heavy load, making it ideal for contractors working in mountainous regions or with demanding attachments.
Hydraulic features included:
- Dual hydraulic filter canisters: One for cooling circuit, one for return filtration
- Gear-type hydraulic pumps with mechanical controls
- Swing gear reservoir requiring 9¼ quarts of 80W-90 gear oil
Mechanical Controls and Operator Experience
Early 690Bs featured long mechanical control sticks—often referred to as “wobble sticks”—that connected directly to valve linkages. These controls required physical effort and offered little finesse compared to modern pilot-operated joysticks.
However, later serial numbers introduced pilot controls in some units, offering smoother operation and reduced fatigue. This transition was not uniform, and many machines retained mechanical linkages throughout their service life.
Operators from the 1980s recall that running a 690B was a full-body workout. Without cab insulation or ergonomic seating, the machine was loud, hot, and unforgiving. Yet it was also reliable. As one veteran put it, “If it had fuel, fire, and fluids, it worked.”
Common Quirks and Field Observations
Several quirks are common among 690Bs:
- Uneven travel motor engagement: One track may start before the other, causing a slow turn in one direction. This is often due to wear in the travel motor spool valves or slight hydraulic imbalance.
- Boom pin wear: The main boom pin tends to wear prematurely, especially if the machine is used for heavy lifting or demolition.
- Fuel consumption: The gear pumps circulate large volumes of oil continuously, even when idle, leading to high fuel usage.
Parts Availability and Restoration Tips
While Deere no longer produces parts for the 690B, many components are still available through aftermarket suppliers and salvage yards. The 6404T engine shares parts with other Deere machines, making engine rebuilds feasible.
Restoration tips:
- Replace all hydraulic hoses with modern two-wire or four-wire braided lines
- Install inline hydraulic pressure gauges for diagnostics
- Use synthetic gear oil in the swing gear reservoir to reduce wear
- Upgrade seat and cab insulation for operator comfort
Conclusion
The John Deere 690B excavator is a relic of a bygone era—mechanical, loud, and built to last. While it lacks the finesse and efficiency of modern machines, it remains a viable option for owners willing to invest in maintenance and restoration. With a turbocharged engine, robust hydraulics, and a reputation for reliability, the 690B continues to dig, swing, and lift decades after leaving the factory. Whether grading farmland in North Dakota or trenching in the Pacific Northwest, this machine proves that old iron still has a place in the dirt.
