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A report from the AgTech Centre

Tracks boost utility of skid steer loaders

Ongoing research suggests that recently developed full track skid steer loaders have some previously unacknowledged load and mobility advantages over traditional wheel models.

The research, conducted by the AgTech Centre in Lethbridge, a part of Alberta Agriculture, Food and Rural Development's Technical Services Division, reveals that track skid steer loaders (not to be confused with wheel skid steer loaders with optional belt tracks that go over and around around the tires) can lift and carry heavier loads than wheel skid steers. They can also offer greater manoeuvrability and, because of their lower ground pressure, tread some surfaces wheel skid steers cannot.

"Skid steer loaders with tracks are relatively new," says AgTech engineer Reed Turner. "Although most major farm equipment manufacturers have added track skid steers to their line ups in recent years, there has not been a full understanding of their benefits and drawbacks. The goal of this research is to fill in those blanks and get them on par with the performance understanding of wheel skid steers."

AgTech evaluated track skid steers with various track designs, with and without suspension systems, comparing them to wheel skid steer loaders. They looked at mobility, lift capability and ride quality.

The basic hydraulic principles and controls of track skid steers are identical to wheel skid steer loaders, says Turner. A major structural difference, and a major advantage, is the mechanics behind the track machine's larger load carrying capability. "Because a track allows a much smaller front roller, the front pivot point can be put closer to the bucket, greatly decreasing a load's forward tipping leverage," says Turner.

"This makes it possible to safely transport heavier loads. All loaders have the capability to breakout far more than they can lift or carry, but track machines can lift and carry more without tipping forward. That is an advantage. In theory, the same effect could be achieved by using a smaller front tire moved forward on a wheel skid steer, but that solution is not practical because of tire limitations."

The track loaders also showed superior mobility and lower ground pressure, both results of their increased ground contact area. "This is an advantage in situations such as landscaping in which the operator wants to minimize damage to the surface," says Turner.

Manoeuvrability was also better with the track skid steers. They displayed better flotation through mud, better turning, and an exceptional ability to back out of heavy snow or mud. "With a wheel skid steer, the tires can spin and dig a hole in the ground and the machine may not have the mobility to climb up out of that hole, particularly while carrying a load," says Turner. "With tracks, the skid steers don't create a hole to have to dig themselves out of."

Although durability was not part of the performance criteria, Turner sees a potential for savings in track skid steers. "With rubber tires, every time the operator skids the machine around a turn, rubber is wiped off the tire," he says. "Track machines have more area to spread the load over and, in theory, should slide less rubber off as they turn."

Overall, ride quality yielded mixed results. The track skid steers generally offered a smoother ride on flat surfaces, but on any kind of rough or bumpy surface the lack of an air cushion made for a jolting ride. Full track suspension systems reduced the jarring effects on the machine, and seat suspensions reduced the effect on the operator, but even then the comfort level did not quite equal that of wheel skid steers.

"A tire cushions the impact so the operator doesn't feel every little bump, while with tracks there is a direct connection to the ground. It's a drawback manufacturers are addressing," says Turner.

Perhaps the biggest drawback of track skid steers, says Turner, is cost. "The track and undercarriage components add significantly to the cost of the machines. Buying one is a matter of evaluating the best tool for the job. In those cases where the machine gets the job done better than the alternative, it can be worth paying the extra money."

The AgTech Centre is part of Alberta Agriculture, Food and Rural Development's Technical Services Division and has a mandate to support all aspects of agricultural sustainability.

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