Equipment Type

48-Minute Operation Changes Cat's Personality

That's how long it took to transform a Caterpillar 236 skid-steer into a real, mud-slinging crawler tractor

August 01, 2005

 

Caterpillar
Loegering's Versatile Track System (VTS) increases a skid-steer loader's traction and flotation in soft material. The VTS lengthens the machine's wheelbase, resulting, says Loegering engineer Ron Hansen, in added stability when backing out of a hole with a load, or when driving onto a trailer without a front-mounted attachment.
Local 150 instructor/technician Jim Yasko

Cat 236

 

Yasko
Local 150 instructor/technician Jim Yasko (above) pops the wheels off the Cat 236 skid-steer, which sits ready (center) for a new type of mobility. Local 150's Sean Connelly (right) aligns the VTS sprocket with the 236's rear hub (via an overhead hoist), while Yasko (in cab) carefully powers the drive system to facilitate the process.

VTS Undercarriage

 

 

 

Yasko and Connelly
Yasko and Connelly installed the second VTS module with the help of a forklift. Although this method was not quite as handy as using the overhead crane, it proved an effective way to install the VTS.

 

On a stormy Thursday morning in mid-May, we watched Local 150's Jim Yasko and Sean Connelly completely change the basic character of a Caterpillar 236 skid-steer loader. The 236 entered the shop as a conventional wheeled machine, but left as a crawler. But this was no tracks-over-the-wheels operation. The skid-steer left with a true crawler undercarriage, complete with suspension. Yasko and Connelly accomplished the 236's wheels-to-tracks transformation, in less than an hour, by installing a Loegering Versatile Track System (VTS).

We'd taken note of the Loegering VTS early this year at an industry trade show, and were intrigued by the company's claim that the new undercarriage system could be fitted to — or removed from — a conventional skid-steer loader in about an hour. So, we asked our friends at Local 150 (International Union of Operating Engineers) if they'd be interested in evaluating the VTS, both from an installation and performance point of view.

Always ready to investigate new equipment, Local 150 agreed. Thanks to the Local's loan of its Cat 236, and to Loegering's loan both of a VTS and regional manager Eric Lunneborg, we were able to convene on that soggy Thursday at the Local's Apprenticeship and Skill Improvement facility in Plainfield, Ill. Yasko and Connelly, both excellent mechanics and instructors in the Local's service-technician development program, already had the Cat 236 on blocks in the facility's well-equipped shop.

VTS design and adaptability

Perhaps the first impressions of those involved in this evaluation had to do with the size, weight and heavy-duty construction of Loegering's Versatile Track System. The VTS package consists of a complete, independent crawler-undercarriage assembly for each side of the machine. And at 1,500 pounds per side, the VTS is no lightweight add-on. Subtract the weight of the wheels, says Lunneborg, and the net gain in machine weight is still usually around 2,200 pounds.

The foundation of the VTS is a beefy adjustable track frame (tunnel), which telescopes at its midpoint to accommodate varying skid-steer wheelbase lengths. Installing the VTS, says Lunneborg, essentially results in extending the skid-steer's wheelbase by about 22 inches, when comparing the distance between the centerlines of the skid-steer's wheel hubs with the centerline distance between the front and rear idlers of the VTS.

Supporting the VTS track frames on each side are three, triple-segment bogey assemblies (rollers), the flanges of which straddle two rows of steel-reinforced guide blocks molded into the inner surface of the rubber track. Further support and alignment of the track are provided by a two-segment bogey under the sprocket, idlers at the front and rear of the track frame, and two tension rollers at the nose of the track — all employing either inboard or outboard flanges that index with the guide blocks. According to Lunneborg, all rotating components in the VTS are sealed and maintenance-free.

The sprocket teeth engage the track via steel-reinforced pockets. According to Loegering engineer Ron Hansen, the VTS sprocket is 18 percent smaller in diameter than most conventional skid-steer wheels, slowing the machine about 1 mph to compensate for any potential stress resulting from the added weight of the VTS. Although the smaller sprocket also increases torque, he says, independent engineering analysis indicates that the added power produces less torsional stress on the axles than would result from installing over-the-tire steel tracks.

The VTS also provides independent suspension for both tracks via a torsion tube, which consists of a square inner shaft rotated 45 degrees inside a square tube and held tightly in place by elastomer cords in the corners. (The cords are frozen before installation, then expand to fill the spaces between shaft and tube.) The torsion tube is linked to the track frame with a pair of curved torsion arms.

When the machine is operating, forces that displace the track vertically are transmitted through the torsion arms and into the torsion tube, where shock loads are dissipated as the cords compress. The net effect is that the undercarriage is allowed to flex for a better ride.

The flex of the undercarriage can be dampened or eliminated, however, by bolting additional "up-stop" plates to the torsion tube's mounting plate. These plates, similar to thick shims, simply limit the travel of the torsion arms. Some operators might prefer a more-rigid undercarriage, for example, says Lunneborg, if the machine is used frequently for fine grading. Also, says Hansen, the suspension system helps equalize loads and assists in forcing the front of the tracks downward for better traction when the sprocket applies power.

At present, two basic VTS sizes are available: one that accommodates mid-range skid-steers with wheelbases ranging from 43 to 51.5 inches, and a second that fits long-wheelbase machines, such as those in Gehl's 7000 Series and Mustang's 2000 Series. According to Hansen, a third size will be available in mid-August for smaller models. The current VTS model has an approximate list price of $15,000.

Part of the overall economic equation involved, says Lunneborg, is that the VTS owner can usually get a higher trade-in price for a used wheeled skid-steer, compared to that of a dedicated rubber-track loader, and can likely keep the VTS for installation on a new machine with only minimal modification.

The transformation

Starting with the Cat 236 on blocks, Yasko and Connelly removed the machine's wheels and installed the Loegering VTS in 48 minutes. They installed the left side with the assist of an overhead crane in 22 minutes, then opted to install the right side with a forklift, because not everyone making the installation will have the luxury of an overhead crane. Right-side installation took 26 minutes.

For each side of the skid-steer, the basic installation of the VTS entails indexing the studs in the skid-steer's wheel hubs with mounting holes in the VTS sprocket and in the flange on the VTS front hub. The front hub can be moved several inches to accommodate alignment, and when secured to the machine, the unit's front wheel hub simply spins the VTS hub and transmits no power to the undercarriage.

During installation, Yasko and Connelly opted to first mount the front of the undercarriage, then, with one or the other in the cab, started the machine and slowly rotated the wheel hubs to index the sprocket and rear wheel hub. Tightening the mounting nuts to 190 pounds-feet and checking track tension completed the installation.

Lunneborg suggested installing an additional up-stop plate on each side, however, to ensure that gussets on the machine's axle hubs wouldn't interfere with suspension components. Adding plates would limit suspension travel a little, he said, but the plates allow adapting VTS to a wide range of machine models.

The Cat 236 had small, bolt-on counterweights at the bottom of the loader towers, and the top of the track lugs just cleared the lower front corner of the counterweights. Lunneborg suggested with the increase in operating weight provided by the VTS, the counterweights probably could be removed and not missed.

We winced when the Cat 236 — with its brand-new, spotlessly clean VTS undercarriage — rolled out of the shop and into the kind of mud that threatens to pull off your boots. The mud, however, didn't faze the VTS, which allowed the 236 to negotiate any situation that Yasko took on, including steep uphill climbs and traversing side slopes.

Yasko was impressed with the added traction and stability of the machine, and noted that the suspension characteristics of the undercarriage were apparent. In his opinion, you could do useful work with the machine even in the adverse conditions at hand. Turns out that Local 150's assistant coordinator, Monte Horne, also was impressed with the Loegering VTS. He bought it.

 

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