Position the chain saw in such a way that your body is
clear of the cutting attachment whenever the engine is
running (fig. 10).
Don’t put pressure on the saw when reaching the end of
a cut. The pressure may cause the bar and rotating chain
to pop out of the cut or kerf, go out of control and strike
the operator or some other object. If the rotating chain
strikes some other object a reactive force (see pages 2
to 4) may cause the chain to strike the operator.
Reactive forces during the cut, including kickback
WARNING!
Reactive forces, that may occur during any cut are
kickback, pushback and pull-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 turn, cause serious or fatal injury. An
understanding of the causes of these reactive forces
may help you avoid loss of control.
The most common reactive forces are
- kickback,
- pushback,
- pull-in.
In order to keep control of your saw, always maintain
a firm foothold. Never work on a ladder, in a tree or on
any other insecure support. Never use the saw above
shoulder height (fig. 9).
9
0
This reaction can occur in a fraction of a second and under
some circumstances, cause the guide bar and chain to
strike the operator with enough force to cause severe or
fatal injury. It may also occur during limbing.
It also occurs when the nose of the guide bar is pinched
unexpectedly, unintentionally contacts solid material in
the wood (fig.12) or is incorrectly used to begin a plunge
or boring cut.
The greater the force of the kickback reaction, the more
difficult it becomes for the operator to control the saw.
Kickback:
Kickback occurs when the upper quadrant of the bar
nose contacts a solid object in the wood or is pinched
(fig. 11). The reaction of the cutting force of the chain
causes a rotational force of the chain saw in the direc
tion opposite to the chain movement, mainly in the plane
of the bar. This may fling the bar in an uncontrolled arc
towards the operator.
2
