Ryobi RY10521B Manuel D'utilisation page 20

 Before any cuts are started, pick your escape
route (or routes in case the intended route is
blocked); clear the immediate area around the
tree and make sure there are no obstructions in
your planned path of retreat. Clear paths of safe
retreat should extend back and diagonally (45°)
to the rear of the planned line of fall. When the
tree begins to fall, you should retreat away from
the direction of fall along a retreat path and at
least 20 feet away from the trunk in case it kicks
back over the stump. See Figure 21.
 Before felling is started, consider the force and
direction of the wind, the lean and balance of
the tree, and the location of large limbs. These
things influence the direction in which the tree
will fall. Do not try to fell a tree along a line dif-
ferent from its natural line of fall.
 The chain saw operator should keep on the
uphill side of the terrain as the tree is likely to
roll or slide downhill after it is felled.
 Remove dirt, stones, loose bark, nails, staples,
and wire from the tree where felling cuts are to
be made.
NOTE: Before every cut, make sure the felling
direction line on the saw housing is aligned with
the desired path for the tree to fall. Figure 22 shows
how the felling direction line is used when making
the back cut.
 Notched Undercut. Cut a notch about 1/3 the
diameter of the tree as shown in figure 23. Make
the cuts of the notch so they intersect at a right
angle to the line of fall. This notch should be
cleaned out to leave a straight line. To keep the
weight of the wood off the saw, always make
the lower cut of the notch before the upper cut.
See Figure 23.
 Felling Backcut. The backcut is always made
level and horizontal, and at a minimum of 2 in.
above the horizontal cut of the notch. See Figures
23 - 24.
 Never cut through to the notch. Always leave a
band of wood between the notch and backcut
(approximately 2 in. or 1/10 the diameter of the
tree). This is called "hinge" or "hingewood." It
controls the fall of the tree and prevents slip-
ping or twisting or shoot-back of the tree off the
stump. See Figures 23 - 24.
OPERATION
BACK CUT
BACK CUT
WEDGE
 On large diameter trees, stop the back cut
before it is deep enough for the tree to either
fall or settle back on the stump. Then insert
soft wooden or plastic wedges into the cut so
they do not touch the chain. The wedges can
be driven in, little by little, to help jack the tree
over. See Figure 25.
NOTE: When bucking or felling with a wedge,
it may be necessary to remove the SAFE-T-TIP
anti-kickback nose guard to allow the bar to be
Page 20 — English
HINGE
2 in. OR 1/10 DIA
2 in.
NOTCH -
APPROX. 1/3
DIAMETER OF
TRUNK
Fig. 23
HINGE
Fig. 24
Fig. 25