Woodworking – Process – Timber harvesting or processing
Reexamination Certificate
2000-08-16
2002-07-16
Bray, W Donald (Department: 3725)
Woodworking
Process
Timber harvesting or processing
C144S004100, C144S034100, C144S034200
Reexamination Certificate
active
06418989
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a standing-stem timber harvesting system for harvesting topped tree trunks directly from the stump, preferably making use of a helicopter, but conceivably a dirigible, to sever, hoist and remove the harvested log.
BACKGROUND OF THE INVENTION
For selective harvesting of individual tree trunks, trees are conventionally individually felled and de-branched. Felling trees often causes damage to the felled tree trunk and invariably causes damage to undergrowth. Removal of the felled tree trunks (i.e., logs) is often difficult, particularly in rugged terrain. Helicopters may be used to pick up felled and trimmed logs and to carry them to a stacking area, to a watercourse, or even directly to a logging truck. One system of lifting and transporting felled timber is disclosed in Jarman U.S. Pat. No. 4,152,019 granted on May 1, 1979. The technique described in that patent requires that conventional felling procedures be used, which can damage the log and inevitably cause damage to the immediate area on which the felled tree falls.
Published Russian Patent Application No. RU 2,095,698 discloses a logging method in which the trunk of a standing tree is cut from two sides, leaving a connecting portion between the saw cuts. Wedges are driven into the saw cuts and vertical members of a securing device are mounted around the tree in such a manner that the connecting portion can later be sawed away. The connecting portion is eventually sawn away, leaving the cut tree standing on the stump (secured in place by the securing device). The cut tree can later be lifted clear by means of a helicopter. This method requires the acquisition of a number of securing devices, if a number of trees are prepared at the same time for being harvested before the arrival of the helicopter. Each such securing device has to be stocked, maintained, transported to the site, installed and removed. Such manipulation complicates the process and increases the overall cost of the logging. Further, according to this method, the ground crew must visit the tree twice, once to saw the tree part way through, and then again later to saw through the connecting portion. As terrain is often difficult, requiring the ground crew to visit the tree twice is time-consuming and expensive.
Despite these earlier methods, there remains a need for an improved method for selectively logging relatively large trees which is economical to utilize for many different situations. Helicopter-implemented techniques have been promising, but have heretofore suffered from disadvantages of which the above-described inadequacies are typical.
SUMMARY OF THE INVENTION
The invention is in one aspect a method of standing-stem log harvesting that allows a tree trunk to be harvested without felling. To this end, once severed from the stump, the tree trunk is removed directly upwards by means of a helicopter or equivalent airborne vehicle.
According to the method, a selected tree is first topped. Then, a first saw cut is made through the trunk of the tree near ground level. This first cut should extend generally horizontally into the tree trunk more than about half the diameter of the trunk at the point of cutting (i.e., more than about half a diameter generally perpendicular to the line defining the limit of cutting), and no more than about two-thirds of such diameter. Then a second cut through the trunk from the opposite side is made, terminating at a cut edge generally aligned with and generally parallel to the cut edge of the first cut, preferably in the same horizontal plane as the first cut, and separated from it by holding wood.
Note that in contradistinction to the two cuts conventionally made to fell a tree, which are conventionally vertically offset from one another, the two cuts of the method of the invention are in generally the same horizontal plane. Further, the present technique, again in contradistinction to conventional practice, does not require any notching of the tree prior to sawing; indeed, such notching would be counterproductive. By “holding wood” is meant a relatively narrow portion of uncut wood extending substantially from one side of the trunk to the other, and sufficiently thick and strong, with auxiliary support, to impede breaking by wind forces, etc. of the topped trunk away from what will become the stump. The auxiliary support conveniently is provided by driving support wedges into both cuts to stabilize the trunk, so that the wedges and the holding wood maintain the trunk stable and upright until it is harvested.
The holding wood is readily frangible in response to generally horizontal pivoting force applied to the trunk near the top in a direction generally perpendicular to the cut edges (and therefore generally perpendicular to the long dimension of the holding wood), thereby to cause the trunk to pivot about the holding wood, and to permit the trunk to be broken away from the stump for removal. The horizontal holding wood breaking force is preferably applied by a grapple supported by and suspended from a helicopter, as described below.
The selection of the thickness of the holding wood will depend upon a number of factors, including the length and diameter of the tree trunk to be harvested, the species of tree, prevailing conditions (especially susceptibility to strong winds), the forces applied by the helicopter rotor wash, and possibly other factors, and is best empirically determined.
When the log is ready to be harvested, a helicopter provided with a suitable grapple suspended underneath the helicopter manoeuvers into position over the tree trunk so that the grapple engages and grips the top of the trunk. Once the grapple grips the top of the trunk, then by moving the helicopter in a direction generally perpendicular to the cut edges (and thus the long dimension) of the holding wood, the helicopter is able to apply sufficient force to the trunk to break the holding wood. (In the process, the helicopter may dislodge some or all of the wedges.) It may be necessary to apply the horizontal pivoting force alternately in both directions perpendicular to the cut edges until the holding wood breaks. A ribbon or other marking may be affixed to the top of the topped tree trunk to indicate (to the helicopter pilot) the direction of the cuts made into the tree trunk, facilitating correct orientation of the helicopter movement required to break off the log from the stump. Once the holding wood is fractured, the helicopter then removes the severed log and carries it suspended in vertical orientation to a selected drop site.
It is conceivable that a dirigible could be substituted for a helicopter, although wind-related problems, slower and less agile maneuverability, and other negative factors associated with the use of a dirigible, would not be easily overcome.
Apparatus according to the invention suitable to implement the foregoing method comprises, in combination, a helicopter and a grapple carried by the helicopter for gripping and carrying the top of a topped standing tree trunk. The grapple in operation accordingly is oriented so that it grips the trunk while the trunk is vertical, in contradistinction to the orientation of grapples used to grip felled trees. The grapple is preferably of the jaws type, having opposed gripping jaws pivotally movable in a generally horizontal plane for engaging the tree trunk top. The grapple is operable from the helicopter for opening and closing thereof, so as to permit the grapple to releasably grip a tree trunk. The grapple is preferably suspended on a wire rope or other suitable load supporting line (sometimes referred to herein as a “support cable”) underneath the center of gravity of the he copter. The load-supporting line should be sufficiently long that the grapple is within the field of vision of the pilot of the helicopter, and may be made longer or shorter as circumstances require. For example, if the forest canopy is relatively shallow, a shorter load-supporting line may be used; if the forest canopy is relatively deep, then a longer li
Barrigar Robert H.
Bray W Donald
LandOfFree
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