At first glance the two new compact track loaders Case is preparing to unveil this month may not look much different from the half dozen or so designs that have been fielded by other manufacturers in the past six years.
But look closer at the undercarriages of these two machines, the 445CT and 450CT, and you’ll notice they look surprisingly a lot like a dozer’s – and for good reason.
Rather than dive into the compact track loader market when it first heated up back in 2000, Case decided to wait and see what its customers thought. By tradition, the company is cautious about technological bandwagons, preferring the tried and true to more sophisticated designs that haven’t yet stood the test of time. After extensive research and interviews with contractors the company came up with a compact track loader system that borrows heavily from its dozer and excavator undercarriages while incorporating the new rubber-track design.
Last month Case invited Equipment World to Wichita, Kansas, to take a close-up look at these new machines at the factory where they will be produced and to talk to one of the contractors involved in their testing. Here’s what we discovered.
Alternating lugs on the tread deliver a smoother ride than bars that span the full width of the track.
The track frame
“One thing we learned from the dozer people is that you don’t want flat surfaces on your track frame,” says Ed Wagner, Case’s compact track loader program manager. “Flat areas collect mud and dirt that can be hard to clean out and interfere with the operation of the machine.”
To combat this, the non-vertical surfaces on the upper track frame are angled to shed material. Several steel mud scrapers are designed into the frame near the forward idler and rear drive sprockets to strike off material before it has a chance to accumulate around moving components. Special attention was given to designing the scrapers to prevent mud and debris from building up between the inside edge of the track and the body of the loader.
Track tension is maintained with a system similar to those of dozers and excavators. A large spring is mounted to the front idler and track tension is maintained by adding grease to a fitting accessible through a cover plate on the frame. (See Figure 1.)
Rigid rollers keep it simple
Another concept borrowed from previous undercarriage designs is the use of rigidly mounted rollers between the idlers. Most other systems anchor their rollers to a torsion bar or some type of flexible suspension so they give somewhat when crawling over rocks, roots and other small obstacles. But Case thought flexible suspensions added a lot of complexity and increased both initial and long-term operating costs. To keep costs low and guarantee durability, it opted for fixed rollers mounted to the track frame.
Adding further to the durability of the rollers, Case is using dual-cone face seals on its rollers and idlers. “With idlers and rollers, the key to longevity is keeping the seals intact,” Wagner says. And since most compact track loaders spend their working lives in mud and water, Case wanted the best possible seal technology – the same face seals as are found on most high-quality dozer and excavator undercarriages.
According to Wagner, some contractors using machines with less robust seals say they replace rollers even before the rubber track wears out (at around 2,000 hours). At a cost of roughly $350 per roller and eight rollers per machine this represents a substantial operating expense. The dual-cone face seals on the rollers for the Case compact track loaders should last as long as they do on dozers and excavators.
The center flange in the triple-flange roller design locks into a groove on the inside of the track and prevents the track from slipping off during side- slope operations.
Rollers lock in track on side slopes
Another issue contractors brought to Case’s attention was the tendency of rubber tracks to spool off or “de-track” from the undercarriage when running on side slopes. To get around this problem contractors jacked up the track tension beyond what would be considered reasonable or avoided side-slope operations entirely.
Case addressed this issue with a triple-flange roller (see Figure 2). The middle flange in the roller is larger in diameter than the outer two flanges and rides in a groove that runs the length of the track. The front and rear idlers also run in this groove, making it almost impossible to corkscrew the track off the undercarriage even when operating under the high lateral loads experienced on side slopes.
Case designed the rubber track with two parallel rows of embedded steel teeth that engage the steel teeth on the drive sprockets. This steel-to-steel contact is less susceptible to wear than rubber to steel, Wagner says. And by limiting the amount of steel in the track to just this narrow band of teeth (rather than full width steel cross bars), the design allows the two outer roller flanges to run on a solid rubber surface for a smooth, cushioned ride. On the top side of the track, the lugs are offset to further enhance the comfort of the ride. (See rubber track photo on this page.)
Track motor aligns with sprocket
The drive system for the new Case compact track loaders consists of a planetary gear box on the outside connected to a two-speed radial piston pump on the inside. This arrangement puts the gearbox bearing in line with the drive sprocket axis. Some of the other arrangements the Case engineers studied offset the gears and the pumps, putting a lot of shear force on the bearing. Once that bearing fails, the sprocket tilts in, Wagner says, and the machine can no longer run. “Ours has a design life of 10,000 hours,” Wagner says. “It’s the same sort of drive system we have on our medium-size excavators.”
Chassis remains the same
Other than the track and undercarriage design, the chassis and all the components on the new 445CT and 450CT are identical to the comparable size machines in the rest of the Case skid-steer lineup, says Rusty Schaefer, marketing manager. These include heavy-duty steel construction, servo-hydrostatic controls, straddle-mounted pins on all the loader-arm and bucket joints and a ride control option that cushions the bucket with a hydraulic oil accumulator.
The undercarriage design adds about 1,000 pounds to the compact track loaders when compared to Case skid steers with equivalent engines. The added weight also boosts breakout force and tipping load. The primary difference between the two models is the 450CT has a bit more horsepower and radial lift for high-production and quick cycle times. The 445CT has a vertical lift configuration. Both have a wheelbase, or track on ground, measurement of 64.5 inches and an overall width of 82 inches.
The Case compact track loaders will be available this spring.
Contractors using compact track loaders
Orvin Koehn, who runs Bluestem Builders in Burns, Kansas, along with his sons Evan and Sheldon, is one of those contractors for whom compact track loaders were made. In addition to residential and commercial construction, the Koehns do a lot of concrete flatwork. For his finish grading he uses his Case 90XT skid steer with a laser-guided grader attachment. And in the soft, loamy soil of Kansas, it doesn’t take much moisture in the soil for their skid steer tires to cut big ruts in their final grade work for concrete slabs.
The Koehn’s have used steel track-over-tire systems, but would like a smoother ride for all-day operations and their laser-guided final grading. They had some experience with renting other brands of tracked loaders, so when Case offered them a chance to give the new 445CT a trial run, they jumped at it.
All three Koehns agree tracked machines will play a role in their future operations. They praised the smooth ride of the 445CT they tested and the Case ride control system. Even while using the bucket as a dozer blade, Orvin says he was able to push material across his grades without leaving any tracks or indentations. When it came to turning and counter rotating, they found the test machine as agile and nimble as the wheeled Case 90XT they use regularly, although for their operations they said they would probably opt for the larger 450CT to get faster cycle times and higher production.