How To Avoid Kickback - Husqvarna 120i Manuel D'utilisation

Felling
WARNING! Unless you have special
!
training we advise you not to fell trees
with a diameter larger than the bar length
of your saw!
Felling is done using three cuts. First you make the
directional cuts, which consist of the top cut and the
bottom cut, then you finish with the felling cut. By placing
these cuts correctly you can control the felling direction
very accurately.
Directional cuts
To make the directional cut you begin with the top cut. Aim
using to the saw's felling direction mark (1) toward a goal
further forward in the terrain, where you would like the tree
to fall (2). Stand on the right-hand side of the tree, behind
the saw, and cut with a pull stroke.
Next make the bottom cut so that it finishes exactly at the
end of the top cut. (Figure 81)
The directional cuts should run 1/4 of the diameter
through the trunk and the angle between the top cut and
bottom cut should be 45°.
The line where the two cuts meet is called the directional
cut line. This line should be perfectly horizontal and at
right angles (90°) to the chosen felling direction. (Figure
82)
Felling cut
The felling cut is made from the opposite side of the tree
and it must be perfectly horizontal. Stand on the left side
of the tree and cut on the pull stroke.
Make the felling cut about 1.5-2 inches (3-5 cm) above the
bottom directional cut. (Figure 83) (Figure 84)
Finish the felling cut parallel with the directional cut line so
that the distance between them is at least 1/10 of the
trunk diameter. The uncut section of the trunk is called the
felling hinge.
The felling hinge controls the direction that the tree falls in.
(Figure 85)
All control over the felling direction is lost if the felling
hinge is too narrow or non-existent, or if the directional
cuts and felling cut are badly placed. (Figure 86)
When the felling cut and directional cut are complete the
tree should start to fall by itself or with the aid of a felling
wedge or breaking bar. (Figure 87)
We recommend that you use a bar that is longer than the
diameter of the tree, so that you can make the felling cut
and directional cuts with single cutting strokes. See
instructions under the heading Technical data section to
find out which lengths of bar are recommended for your
saw. (Figure 88)
There are methods for felling trees with a diameter larger
than the bar length. However these methods involve a
much greater risk that the kickback zone of the bar will
come into contact with the tree. (Figure 4)
26 – English
WORKING TECHNIQUES
Freeing a tree that has fallen badly
Freeing a "trapped tree"
It is very dangerous to remove a trapped tree and there is
high accident risk.
Never try to fell the tree that is trapped.
Never work in the risk zone of the hanging trapped tree.
(Figure 89)
The safest method is to use a winch.
• Tractor-mounted (Figure 90)
• Portable (Figure 91)
Cutting trees and branches that are in tension
Preparations: Work out which side is in tension and where
the point of maximum tension is (i.e. where it would break
if it was bent even more). (Figure 92)
Decide which is the safest way to release the tension and
whether you are able to do it safely. In complicated
situations the only safe method is to put aside your chain
saw and use a winch.
General advice:
Position yourself so that you will be clear of the tree or
branch when the tension is released. (Figure 93)
Make one or more cuts at or near the point of maximum
tension. Make as many cuts of sufficient depth as
necessary to reduce the tension and make the tree or
branch break at the point of maximum tension. (Figure
94)
Never cut straight through a tree or branch that is in
tension!
If you must cut across tree/limb, make two to three cuts,
one inch apart, one to two inches deep. (Figure 95)
Continue to cut deeper until tree/limb bends and tension
is released. (Figure 96)
Cut tree/limb from outside the bend, after tension has
been released.

How to avoid kickback

WARNING! Kickback can happen very
!
suddenly and violently; kicking the chain
saw, bar and chain back at the user. If
this happens when the chain is moving it
can cause very serious, even fatal
injuries. It is vital you understand what
causes kickback and that you can avoid
it by taking care and using the right
working technique.
What is kickback?
The word kickback is used to describe the sudden
reaction that causes the chain saw and bar to jump off an
object when the upper quadrant of the tip of the bar,
known as the kickback zone, touches an object. (Figure
69)