IBEA IB 5000 Manuel D'instruction page 22

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GB
Cut the notch determining the falling direction of the tree. The
notch will have to be at right angles to the felling direction, as
close as possible to the tree base and shall reach a depth
equalling 1/5 of the trunk diameter. The notch opening height
shall not however exceed its depth (fig. 14).
After cutting the notch, the felling cut should be made. This
should be located above the notch base and it should be
perfectly horizontal.An uncut area about 1/10 of the trunk size
should be left between the notch bottom and the horizontal
cut: this area, called a hinge, allows the tree falling direction
to be controlled.
Promptly insert in the felling cut wooden or synthetic material
wedges.
Legend (fig. 14-15)
1 - Hinge
2 - Notch
3 - Felling cut
Promptly insert in the felling cut wooden or synthetic material
wedges.
For small diameter trees, the chain saw will lever on the hook
placed right behind the hinge (fig. 15).
For large diameter trees, a cutting progression is required.
The first cut shall be made in such a way that the bar head
grazes the hinge levering on the hook.
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The next cut shall be made without removing the bar, to
prevent felling plane offsetting.
13
The final cut shall be made by placing the chain saw behind
the hinge levering on the hook (fig. 16). In the event of
exceptionally large diameter trees, there may be a core left
after this cutting progression which may after effect the felling
direction.
This core should therefore by cut into with a dive cut starting
from the bottom of the notch.
In soft broad-leaved species, this cut is used to eleminate
any internal tension in the trunk.
WARNING: dive cuts should only be performed by
experts in this technique.
In the event of dive cutting, an incision is made when the
diameter is very large, eceeding two times the bar lenght. To
make the incision, the bar should be slanting rather than
vertical with respect to the trunk (fig. 17).
14
Cut with the tip into the trunk to reach a depth equalling two
times the bar lenght, then carry out the incision proper,
bearing in mind that there is a kick-back risk (fig. 18 and fig.
19).
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