Pushback:
Pushback occurs when the chain on the top
of
the bar
is suddenly stopped when
it
is pinched, caught or
encounters
a
foreign object in the wood. The reaction
of the chain drives the saw straight back toward the
operator causing
loss
of saw control. Pushback fre-
quently occurs when the top of the bar is used
for
cutting (fig.
14).
14
To
avoid
pushback
1.
Be alert to forces or situations that may cauE
material
to
pinch the top of the chain.
2.
Do
not cut more than one log at a time.
3.
Do
not twist the saw when withdrawing the bar
from a plunge cut or under buck cut (figures
25
to
27
and
33,
pages 13 and
15),
because the chain
can pinch.
Pull-in:
Pull-in occurs when the chain on the bottom of the bar
is suddenly stopped. The chain on the bottom
of
the
bar stops when it is pinched, caught or encounters a
foreign object in the wood (see fig.
15).
The reaction of
the chain pulls the saw forward, causing the operator
to lose control.
Pull-in frequently occurs when the spike bar of the
saw is not held securely against the tree or limb and
when the chain is not rotating at full speed before it
contacts the wood.
15
To
avoid
pull-in
1.
Always start a cut with the chain rotating at full
speed and the spike bar in contact with the wood.
2.
Pull-in may also be prevented by using plastic
wedges
to
open the kerf or cut.
Cutting
techniques
Felling
Felling is cutting down a tree.
Before felling a tree, consider carefully all conditions
which may affect the direction of fall, including:
The intended direction of the fall.
The neutral lean
of
the tree.
Any unusually heavy limb structure.
Surrounding trees and obstacles.
The wind direction and speed.
'
WARNING!
Always observe the general condition
of
the tree.
Look
for
decay
and
rot
in
the trunk.
If
it
U
rotfed
vibrate loose
and
fall
on
the
operator. When
fellina
._
on
aslope, the operator should
stand
on the up-hi
When felling in the vicinity of roads, railways
and
power lines, etc., take
extra
precautions (see fig.
16).
Inform the police,
utili
company or railway
authority before beginning to cut.
WARNING!
Use extreme caution when cutting small size brush
and saplings which may easily catch the chain and
pull you
off
balance.
11
To Next Page
Loading...
