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Timberjack 660C Skidder Performance and Mechanical Insights
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Timberjack’s Legacy in Forestry Equipment
Timberjack, founded in Canada and later acquired by John Deere in 2000, was a dominant force in the forestry equipment market for decades. Known for their rugged skidders and forwarders, Timberjack machines were designed to withstand the punishing conditions of logging operations across North America, Scandinavia, and Russia. The 660C skidder was part of Timberjack’s final generation before the brand was absorbed into Deere’s forestry division, and it remains a respected workhorse in the woods.
The 660C was engineered for high-production logging, particularly in large-scale clear-cut and pulpwood operations. With a powerful engine, robust frame, and hydraulic grapple system, it was built to drag heavy loads over rough terrain with minimal downtime.
Terminology Notes
  • Skidder: A forestry machine used to drag logs from the cutting site to a landing area.
  • Grapple: A hydraulic claw used to grab and hold logs during skidding.
  • Arch: A rear-mounted lifting structure that raises the front of the log bundle to reduce ground friction.
  • Winch: A cable system used to pull logs from inaccessible areas or assist in recovery.
Core Specifications and Operating Profile
  • Engine: John Deere 6068T turbocharged diesel
  • Horsepower: ~185 hp
  • Transmission: 4-speed powershift with torque converter
  • Operating weight: ~33,000 lbs
  • Tire size: 30.5L-32 or 35.5L-32 depending on configuration
  • Grapple capacity: ~1.2 to 1.5 cubic meters
The 660C features a center-articulated frame for tight turning in dense woods, a heavy-duty arch for lifting log bundles, and a hydraulic grapple with joystick control. The cab is ROPS/FOPS certified and includes climate control, suspension seating, and visibility enhancements for long shifts.
Field Performance and Operator Feedback
Operators consistently praise the 660C for its:
  • Strong pulling power in wet and hilly terrain
  • Responsive hydraulic system for grapple control
  • Balanced weight distribution for stable skidding
  • Durable drivetrain under heavy loads
  • Ease of maintenance with accessible service points
In one case, a logging crew in British Columbia used a 660C to recover wind-thrown timber after a storm. The machine’s winch and arch allowed them to extract logs from steep slopes without damaging the soil or surrounding trees.
Common Issues and Mechanical Considerations
Despite its strengths, the 660C has a few known mechanical challenges:
  • Transmission hesitation when shifting under load
  • Hydraulic leaks around valve blocks and grapple cylinders
  • Electrical faults in joystick wiring and dash indicators
  • Winch cable wear due to misalignment or overloading
  • Cooling system strain during summer operations in dense brush
Solutions and recommendations include:
  • Flush transmission fluid every 1,000 hours and inspect clutch packs
  • Replace hydraulic seals and hoses proactively during seasonal service
  • Use dielectric grease on electrical connectors and inspect harnesses quarterly
  • Install cable guides and tensioners to reduce winch wear
  • Clean radiator fins weekly and consider auxiliary fans in hot climates
Preventive Maintenance and Long-Term Care
To extend the life of the 660C:
  • Grease all pivot points and grapple joints every 50 hours
  • Inspect tire pressure and sidewall integrity weekly
  • Replace fuel and air filters every 500 hours
  • Monitor engine temperature and transmission pressure during heavy pulls
  • Keep a log of winch usage and cable condition to prevent sudden failures
For machines operating in cold environments, install block heaters and use winter-grade hydraulic fluid to maintain responsiveness.
Design Simplicity and Operator Experience
The 660C’s cab layout is intuitive, with analog gauges, ergonomic controls, and wide visibility. The joystick-operated grapple allows precise log handling, and the arch provides excellent lift without excessive strain. Unlike newer machines with touchscreen diagnostics, the 660C relies on mechanical feedback and straightforward service routines.
Operators often describe the machine as “predictable and powerful,” especially in rough terrain where traction and torque matter most. Its ability to recover from bogs and climb steep grades makes it a favorite in challenging logging zones.
Conclusion
The Timberjack 660C skidder remains a benchmark in forestry equipment for its pulling power, mechanical reliability, and operator-friendly design. While it requires attentive maintenance and occasional hydraulic or electrical repairs, its performance in the field continues to earn respect. In the world of timber extraction, the 660C proves that legacy machines still have a place in modern logging operations—especially when the woods get tough and the loads get heavy.
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