Stihl TS 440 Instruction Manual page 18

English
(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 (push
back). 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 – push back 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.
16
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.
Be alert to potential movement of the
workpiece or anything else that could
cause the cut to close and pinch, bind or
clamp the wheel. In order to reduce the
risk of pinching, binding or clamping,
support the workpiece in such a way that
the cut remains open during the cutting
process and when the cut is finished
(see illustration). Never make a cut that
results in a binding of the wheel. If you
cannot properly support the workpiece,
do not use a cutting-off machine to make
the cut; select another tool or method.
Where there is a possibility of a pinch,
you should leave an uncut portion of the
workpiece that prevents the cut from
closing and pinching the wheel, which
can later be broken manually using a
hammer or other appropriate tool. If you
are making a complete cut, make sure
that the final, separating cut is made at
the top of the workpiece using the
bottom of the wheel, with the guard of
the machine pushed fully forward to the
forward stop position. In this way, if there
is any residual pinching, it will be at the
bottom of the wheel, where it may result
in pull-away, but not in kickback. Be alert
for pull-away.
Objects to be cut always must be
properly supported and must be secured
against pinching, rolling away, slipping
or vibration.
TS 440