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LOGGING

MOUSE among the 

ELEPHANTS

Oregon logger Mark Smith's mouse-like Posi-Track harvester is surviving quite well among the elphants-the larger machines. 

By Tony Kryzanowski

An Oregon logger's use of a small crawler dozer with a feller buncher attachment in careful logging environments has been compared to a mouse that scurries among the feet of a herd of elephants. The elephants in this case are the large mechanized harvesters typically used in today's logging environment in either clearcut or select cut applications. For the past three years, Mark Smith has been using a 7500-lb Posi-Track dozer to commercially thin both natural and plantation stands on private woodlots throughout the Pacific Northwest. 

During that time, he has used both a harvester/processor and feller buncher attachments-manufactured by Posi-Track dealer DAVCO Manufacturing, headquartered in Grande Prairie, Alberta-on the carrier. DAVCO Manufacturing is co-owned by Dave Fenton. Fenton was an owner of the company that manufactured the Ultimate line of fixed-mount harvester/processor heads before it was sold to Quadco Equipment. The Posi- Track line of crawler dozers is manufactured in Minnesota. While the concept of using low-cost smaller equipment and harvester/processors in a thinning application is not new, the use of a low cost, low ground pressure dozer with a harvesting attachment is. 

The undercarriage on Smith's 4520 Posi-Track dozer comes equipped with Kevlar tracks that are propelled by 52 rubber wheels. The independent suspension on each wheel assembly results in superior flotation and remarkable ground pressure- only three pounds per square inch. That is less ground pressure than a human footprint. "It's the undercarriage that really makes this carrier quite unique in relation to any other type of vehicle that is out there," says Smith. "The tread doesn't dig in and grip like a normal grouser would on a metal dozer track. It really does minimal damage in terms of chewing up the ground." He estimates that owners should expect at least 2,000 hours of production before tracks need to be replaced. They retail for about $4,500 per track. The dozer is designed for use on dirt, not rock or gravel roads, according to Smith.

The independent suspension on each wheel assembly results in superior flotation and remarkable ground pressure—only three pounds per square inch. That is less ground pressure than a human footprint.

With its superior flotation, the Posi-Track harvester can access wet areas that larger, heavier carriers must avoid. With its superior flotation, the Posi- Track dozer can access wet areas that larger, heavier carriers must avoid. Again, the concept of gaining access to wet areas with a dozer-type carrier is not new. A good example is Cat's 527 tracked skidder. What's new about this equipment combination is that Smith is using a tracked dozer to both harvest and skid the wood. 

The Posi-Track dozer is extremely versatile. In addition to his harvester/processor and feller buncher implements, Smith can also attach a grapple, bush cutter and dozer blade. DAVCO Manufacturing is even designing a backhoe attachment for it Smith works in areas with plenty of slope, so the stability of a dozer carrier versus a mini-excavator made more sense. He says the dozer and feller/buncher combination remains economically viable to about a 25 per cent slope, at which time cable yarding and heli-logging become more economically practical. However, the dozer is rated up to a 68 per cent slope. 

Smith warns that this Posi-Track carrier is not a replacement for larger mechanized harvesting equipment. It is a product suited for a niche market, specifically commercial thinning in environmentally sensitive areas, particularly where stability is an issue. The carrier is powered by a 4045T John Deere diesel turbo engine that delivers 115 hp. It is five feet, nine inches wide, and nine feet, five inches long. DAVCO Manufacturing's QC 1200 feller buncher head weighs in at 1,100 lbs and is 57 inches high and 42 inches wide. It comes equipped with a 36-inch diameter high-speed 1 5/8ths kerf rotatable square tooth saw. 

The Posi-Track dozer is extremely versatile. In addition to his harvester/processor and feller buncher implements, Smith can also attach a grapple, bush cutter and dozer blade.

It is available with or without a spring-loaded accumulator arm. Although the crawler and feller/buncher combination is a lower cost alternative to larger name brand equipment-at just over $105,000-it is limited to harvesting timber up to 20 inches at the butt. While the head is rated at a maximum capacity of 14 inches, Smith says he can harvest timber up to 20 inches with a couple of cuts. He would not recommend tackling trees larger than 20 inches. In order to achieve a reasonable return on investment, he avoids thinning pulp wood and aims to recover highervalue timber that is capable of producing dimensional lumber.

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