10
Reactive
forces
during
the
cut,
including
kickba-*
WARNING!
Reactive forces, that
may
occur during
any
cut are kick-
back,
pushback
andpull-in.
Reactive forces
·can
··be
dangerous!
In
any chain
saw,
the powerful force
used
to
cut
wood
can
be
reversed
(and
work against the operator).
If the rotating chain is suddenly stopped
by
contact
with
any solid object like a log or branch or is pinched, the
reactive forces Instantly
oCcUr.
These reactive forces
may
result
in
loss of control which
may,
in
tum, cause serious
or
fatal injury.
Anunderstaiidin~i
of the
cauSes
of
these
reactfveforces
may
help you
aVoid
loss of control.
The
most
common
reactive forces are
':"ldckback,
-pushback,
-pull-in.
Kickback:
Kickback occurs
when
the upper quadrant of the bar
nose
contaCts
a solid object
in·
the
woOd
Or
is pinched
(III.
11).
The
reaction of the cutting force of the chain 'causes a
rotational
force of the chain saw'in the directidn
Opposite
to the
chain
movement, mainly in the plane
of
the
bar.
This
may
fling
the bar
in
an
uncontrolled arc mainly
in
the plane
of the
bar.
Under
some
circumstances the bar
·moves
towards the
operator
who
may
suffer severe or fatal
injury.
It may also
occur during limbing. It also occurs
when
the nose of
the
guide bar is pinched
unexPeCtecDY,
unintentionally
contacts
sorld
material
in
the wood (ill.
12)
or is Incorrectly
used
to begin a plunge or
bOring
cut.
The greater
the
force
of
the kfckb8ck reaction, the
more
difficult it becomes for the operator to controf the
saw.