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CAPTION: The new 9RX tractor marks John Deere's first entry into the four-track category and rounds out its 9 Series, which already had wheels and two tracks. (Photo courtesy John Deere)
WATERLOO, Iowa (DTN) -- Tracked-tractor users have another option to consider. John Deere used its Waterloo tractor factoryonSeptember 1, 2015,as the site to introduce the 9RX Series of high horsepower tracked tractors. Deere's 9 Series tractors now have wheels, two tracks and four tracks to accompany its 9RT Series.
Why four tracks? Articulated tractors with four tracks are better than non-articulating tractors with two tracks for some customers' circumstances, said Jerry Griffith, John Deere mid- and large-tractor product marketing manager. With their long, powerful bases, two tracks give excellent straight-line pulling, but they tend to slip during turns. Because the 9RX is articulated, they are more maneuverable. "Four tracks can turn better under load than two tracks," Griffith said.
Another advantage: When working near wet areas, four tracks will let you get closer than two tracks. If you get too close to a wet area with a two-track tractor, the inside track can slip and spin faster. When that happens, steering can become tricky. "If you get into trouble with a four-track tractor, you are better able to get out of it because it is articulated," Griffith said.
That same articulation can help on sidehills when pulling an implement. With two tracks, an implement that drifts downhill can cause steering issues that require a driver to have to compensate more. Articulation helps a four-track tractor "stick to the hill better," Griffith said.
And, when going over hills -- terraces, for instance -- a two-track vehicle gives a teeter-totter effect: The front goes up, up up and when it reaches the center point, it comes down quickly. Not so with an articulated tractor, which flexes in the middle to glide better over the incline.
The 9RX oscillates 15 degrees side-to-side at the center of the tractor and 20 degrees up and down at the undercarriage. It has a turning radius of less than 20 feet.
DIFFERENT THAN COMPETITORS
It's inevitable when talking about the 9RX to compare it to the Case IH Quadtrac, which has been on the market since 1996. One key difference, Griffith said, is the 9RX's unique undercarriage, which is taller than the competitor and has larger drive wheels. Its configuration makes the track itself 20% longer, which means 20% less travel, 20% less wear and longer track life.
Deere designed the new undercarriage to be low maintenance. For instance, the operator will have to check oil in the sealed cartridge mid-rollers only every 1,500 hours and change oil every 10,000 hours. The 9RX uses the same mid-rollers as the 8RTs, which means the design is proven and parts are already available. And, if they ever have to be replaced, only eight bolts must be removed.
The tracks on a 9RX have a positive drive mechanism; inside drive lugs engage with sprockets. Outside tread bars are for traction. The result is an extremely efficient transfer of power to the ground. By contrast, two-track systems rely on friction. Large rear drive wheels engage tracks rubber to metal and inside track lugs are guides to keep the tracks centered on the drive wheel; they do not transfer power. Such a friction-based system works well with large drive wheels. It would not work as well on four-track systems because their drive wheels are not as large, and friction would be less efficient than on positive drive.