Makita EA3500S Manual De Empleo Y De Seguridad página 11

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).
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 12 to 14) 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.
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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.
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.
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