Caterpillar's SystemOne undercarriage takes much of the friction, and the wear, out of track chain by lubricating the pin and bushing joint and allowing the bushing to turn while under sprocket drive load. Cat's rotating-bushing undercarriage, on the market for about 11 years, did the same thing but its seals wouldn't withstand impact.
Caterpillar designed a whole new premium undercarriage system around the SystemOne pin-and-bushing cartridge because it can handle any conditions. Cat's testing indicates that the new system will cut track costs by 35 to 70 percent.
There are about 350 D4s and D6s working on SystemOne in North America and Europe (it is available for D3 through D6R tractors and 953 and 963 track loaders). Tom Neeley, senior marketing consultant for Caterpillar undercarriage, says they've logged 300,000 hours in a variety of applications including logging, stumping, clearing, road building, side sloping, and fine grading in quarries, mines, sand, and gumbo without a single failure — not one joint or other component.
The cartridge is the core of SystemOne. It's sealed and lubricated for life. Unlike the press fit between the bushing and pin in Cat's rotating-bushing track, the SystemOne cartridge is assembled in a clean-room environment and laser welded. New load rings improve the joint, and Neeley says automated assembly delivers precise tolerances. With endplay secured, the seals last as long as the steel, and lubrication stays in the cartridge. The rotating bushing significantly reduces wear and eliminates the need for cartridge turns.
Cat redesigned most of the other undercarriage components in order to make them last as long as the new cartridge. Chain links are different. All of the links — inside, outside, left and right — are straight and exactly the same. The only difference is their orientation.
Chain is composed of box sections — two links turned in and pinned together by two cartridges. Each box section is attached to the next by a pair of links turned facing out. Neeley says the straight links are stronger and resist impact better.
"It makes for a more forgiving track chain," says Neeley. "Because the pin turns in the bushing, there's no need to avoid high-speed reverse operation. Tight track should still be avoided because of the other detrimental affects to the machine and operating cost, but it's not as critical to getting the full life out of this track."
One advantage of the box-section design is ease of service. If a cartridge requires service, three shoes and four outside links are pulled off (with special tooling), and the entire box section can be replaced without leaving the jobsite. Any of the box sections can be removed this way, so the system doesn't require a master link. A master link option is available, however.
SystemOne track is compatible with standard idlers. But when the new Center Tread Idler is installed, Cat claims it improves link wear life by 35 to 70 percent. The Center Tread Idler is narrower and only contacts the bushings. Scalloping of link rails is eliminated, and idler wear is also reduced.
Like the Center Tread Idlers, SystemOne sprockets last two to three times as long as the track, according to Neeley. Long-life segments and the new cartridge make this possible.
To improve track guiding, the diameter of track roller flanges has been increased. It's 33 percent taller on the D6, for example. And track guides are redesigned for better control. The guides ride against the link rails rather than pin ends, and their tapered shape funnels the track onto the roller treads.
SystemOne requires track shoes with a straight bolt pattern (rather than an offset one), but the same shoe types — moderate service, extreme service, trapezoidal and multi-grouser — are still available. Cat recommends extreme service shoes for all SystemOne users because they're most likely to match the service life of the rest of the undercarriage. Neeley says Cat is developing the next level — super-extreme service, if you will — for users who work in extreme conditions.
SystemOne costs about 25 to 30 percent more than traditional track, but its hourly cost should be lower if it meets Cat's expectations. Caterpillar is so convinced of SystemOne's capabilities that the company is willing to back dealers who guarantee a 50 percent improvement in track life, with a maximum of 6,000 hours, for customers who already have Custom Track Service records.