Mounting the cab on the tractor's front frame puts the operator close to the six-way dozer blade and looking straight down to the blade through the cab's broadest stretch of glass even in turns.
Tables: | - Key Specs: John Deere 764 HSD
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John Deere says a significant portion of its customers are looking for a grader with greater flotation and better maneuverability, and a faster dozer that won't damage pavement. In responding with the 764 High-Speed Dozer, Deere offers those buyers an articulated-frame dozer that can grade accurately at up to 6 miles per hour and offers operators an amazingly good view of the work at the blade.
"Applications for this machine include site preparation, road building — anything where you're spreading material, especially that last foot of material on the jobsite," says Keith Berning, manager of product marketing at Deere. "It's not designed to do the stump grubbing, the heavy digging and pushing work that you might do with another dozer. Finish grading work is where you're really going to see the greatest benefit of the 764 HSD, capitalizing on its speed to do that job twice as fast as what you can do with a current crawler."
Deere unveiled a prototype of what the company is calling "the first new machine form the construction industry has seen in decades" in March at Conexpo-Con/Agg 2008, and promised production units of the rubber-tracked 764 HSDs for sale in 2009.
The 764 HSD weighs in at 32,000 pounds and is powered by a Tier 3 John Deere PowerTech 6.8-L engine rated at 200 horsepower. Four 24-inch-wide tracks put 4,989 square inches of track on the ground.
"With total ground pressure of about 6 psi, it's a little higher than a low-ground-pressure crawler, which might be around 4½ or 5 psi," says Berning. "A motor grader is going to be up in the 40-psi range."
Berning says customers who have worked the 764 HSD agree the machine will deliver a grade to plus or minus 1/8-inch of accuracy at 6 mph (faster, in some conditions). That's about as fast as a motor grader and twice as fast as the Deere 850J, which carries the same-sized blade and can work at the same level of precision.
The 764 HSD is available with Deere's "plug-and-play" Integrated Grade Control, meaning the dozer arrives from the factory pre-wired and ready to add the operator's favorite laser/GPS system.
Rubber track units — jointly developed with track-maker Camoplast for traction and durability in this unique application — are crucial to the high-speed dozer roading at speeds of up to 18 mph. Not only do the rubber tracks protect pavement, but each track module has a hydraulic shock absorber, which also acts as a track tensioner, to keep the machine stable at transport speed. (The suspension automatically locks out and becomes rigid to improve fine-grading performance when the 764 HSD is grading.) Drive torque is delivered to the rubber track belt with a combination of positive contact using a sprocket and friction to deliver long belt life. The undercarriage is backed by a 3,000-hour wear assurance program.
Hydrostatic drive not only offers infinite control of speeds from 0 to 18 mph, but it also works to distribute power evenly to each track under changing load conditions. When the machine articulates, the inside track slows and outside track speeds up automatically to improve turning, reduce slippage, and preserve the track. While turning, the four shorter tracks are swept over less ground than two long tracks, extending life and improving performance compared to machines with just one pair of tracks.
The operator's station is mounted close to the 12-foot, six-way dozer blade on the tractor's front frame. The operator's station turns to follow the blade when the tractor turns, giving the operator an unprecedented panoramic view of the blade all the time.
The 764 HSD features familiar John Deere crawler controls. Two right-hand levers handle blade functions, while the left controls perform steering and forward-neutral-reverse direction changes. But the cab also includes a steering wheel for more-comfortable control of the machine at road speeds.
A rear hitch and two hydraulic circuits plumbed to a bulkhead at the rear of the machine allow the dozer to pull implements like scrapers, discs, box blades and compactors. With a suspended tractor, the hitch chosen is designed for pulling rather than weight transfer. The tractor will require dolley-type implements.
"The hitch and auxiliary hydraulic ports will help customers get more work done on the jobsite with one machine," Berning says. "It even creates the opportunity to finish grade and seal in one pass."
While the 764 HSD is an entirely new machine form, it was developed with reliable, rugged components from other Deere-engineered products with years of experience on the job — about 60 percent of its parts come from other machines in the Deere line. The power train, hydraulics, blade and C-frame are from John Deere crawlers; while the cab, engine, controls and articulation joint come from Deere four-wheel-drive loaders.
Deere's Quad Cool system helps keep the cooling elements clean and is less susceptible to plugging. Coolers are arranged in a cube, side by side around the fan rather than stacked in front of it, to allow easy cleaning access to both sides of each cooler. The standard hydraulic fan automatically reverses direction at regular intervals to eject debris that might have been drawn up against the coolers, minimizing manual cleaning time.
Suggested retail price of the 764 HSD is expected to be similar to Deere's 850J — a conventional crawler dozer with similar horsepower but weighing 10,000 pounds more — at about $330,000.
