John Deere recently introduced enhancements to its larger crawler dozers. The 700J continues to use the PowerTech 6068T turbocharged engine with ratings from 115 to 123 hp. New to the machine is the engine and transmission protection system that keeps the engine from operating at critical levels during warm up. Engine speed is also infinitely controlled with a simple rotary dial, eliminating the need for the throttle lever, linkage and cable. As an added bonus, the engine oil change interval has been increased to 500 hours.
A dual-path hydrostatic drive transmission provides infinite speed control, a power management system, live power turns, counter-rotation, dynamic braking and automatic tracking control. The Speed-in-Grip (SIG) transmission control system - standard on J-Series dozers - features an increased number of user-definable rates, allowing greater flexibility in tailoring the operating characteristics of the machine to the operator's preference.
Like the 700J, the 750J and 850J have also been completely redesigned. Blade control and machine balance can be fine-tuned by choosing the main frame suited to the individual application. Twelve track frame choices provide the flexibility to deliver multiple undercarriage configurations for each model. Improvements have also been made to the 13 different blade options available.
The 750J and 850J are equipped with PowerTech engines, ranging from 145 to 200 hp, and incorporating rotary dial control. The cooling system offers a variable-speed, hydraulically driven cooling fan that turns only at the speed necessary to cool the system. An optional automatic reversing fan is available.
Both models also incorporate the dual-path hydrostatic drive powertrain and SIG transmission control system. New final drives produce 14% higher torque compared to the C-Series models.
The hydraulic system is completely redesigned to feature a closed-center system with variable displacement, load-sensing hydraulic pump and pilot controls.
The operator's station has also been totally redesigned. Features include larger door openings and lighter doors; a new decelerator pedal combining decelerator and brake functions; a new dash panel with backlit rocker switches and new monitor display unit; and a new centralized vehicle electrical center accessed via a cover in the operator's station.
A "metallurgical breakthrough"
In addition to its model updates, John Deere announces a "metallurgical breakthrough" in dozer undercarriage coatings that is said to eliminate the need for bushing turns.
"The new SC-2 metallurgy is a giant step forward in the field of undercarriage design - it delivers twice the wear life over standard bushings," says Tim Wodrich, undercarriage engineering supervisor.
"SC-2 will take a huge bite out of downtime, now that turning bushings is no longer necessary."
The SC-2 Extended-Life Undercarriage features coated bushings that are the result of a patented process called GOPALITE. The process produces a water-based slurry from a heavy alloy-metal powder and several organic additives. The slurry formula suspends the alloy powder and is used to apply the coating to the part surface, producing a coating that's uniform in both thickness and consistency.
During intensive laboratory testing, the coating has proven up to 25% harder than chrome plating, says Dr. Gopal Revankar, John Deere senior staff metallurgist and developer of the GOPALITE process. It has also gone through three years of field testing on dozers working year-round with high-impact loads in extremely abrasive soil conditions. One chain on each dozer used SC-2 coated bushings and a second used normal production bushings.
"In each dozer, the SC-2 coated bushings showed more than 100% improvement in wear life over the production bushings," says Wodrich.
SC-2 coated bushings are compatible with existing John Deere undercarriage designs, and will fit many other dozer brands, as well.