Stihl TS 440 Manual De Instrucciones página 18

English
can occur instantly and may result in the
operator losing control of the cut-off
machine, which, in turn, may result in
serious or fatal injury. An understanding
of the causes of these reactive forces
will help you avoid them and loss of
control.
Reactive forces are exerted in a
direction opposite to the direction in
which the wheel is moving at the point of
contact or of the pinching/binding. If the
wheel is slowed by frictional contact with
a solid object, the resulting reactive
forces are normally moderate and
readily controllable by an operator who
is holding the machine properly. If,
however, the wheel is abruptly slowed or
stopped by a severe pinch or bind, the
reactive forces may be substantially
greater. The greater the force
generated, the more difficult it will be for
the operator to control the cut-off
machine. Loss of control can result in
severe personal injury or death.
Pull-away, Climbing, Pushback,
Pinching and Rotational Kickback
Forces
The most common reactive forces are
pull-away and climbing. If the contact is
at the bottom of the wheel, a cut-off
machine will try to pull away from the
operator (pull-away). If the contact is at
the front of the wheel, the wheel may
16
attempt to climb the object being cut
(climbing). When the guard is opened on
the TS 440 to expose the top portion of
the wheel, contact in this top portion of
the wheel can cause the machine to
move linearly toward the operator
(pushback). Any of these reactions can
result in loss of control and severe
personal injury or death.
Pinching occurs when the piece being
cut closes on the wheel. A severe
binding may also occur if the wheel is
substantially sideloaded in the cut or if
an improper or damaged diamond
cutting wheel begins or ceases to
wobble in the kerf. The location of the
pinch or bind on the wheel will determine
the direction the machine will move in
response to any reactive force that is
generated pushback from the top of
the wheel, pull away from areas below
the upper quadrant of the wheel.
However, if the wheel is severely
pinched or bound in the upper quadrant
at the front of the wheel, the wheel may
be instantly thrown up and back towards
the operator with significant force in a
rotational kickback motion. Such
kickback situations can and always
should be avoided.
Pinching or binding of the wheel can be
prevented by proper support of the
workpiece (see below), proper working
technique (e.g., not side loading the
wheel and standing outside the plane of
the wheel) and by the use of properly
designed, manufactured and maintained
wheels that do not wobble or have
friction-generating abrasive material on
their sides.
Reducing the Risk of Kickback Injury
WARNING
To reduce the risk of kickback injury,
avoid cutting with the upper quadrant of
the wheel (illustrated above) whenever
possible. Be especially cautious for a
pinching or binding of the wheel in this
area, which can cause severe reactive
forces in a rotational kickback motion.
Avoid wedging action. The severed part
of a workpiece must fall free and not
wedge, bind or clamp the abrasive
cutting wheel.
TS 440