Makita DBM230 Operating Instructions Manual page 26

Install an appropriate extension between drill bit and motor. If the drill bit holding
fixture is 1¼ " do not forget to install the copper rings in order to facilitate the
loosening of the drill bit.
Overload Protection
In order to protect the operator, the motor and the drill bit, the DBM 230 is
equipped with mechanical, electronic and thermal overload protection.
Mechanical: If the drill bit is suddenly blocked in the borehole, a slip clutch
will disengage the drill bit from the motor.
Electronic: An LED is built into the housing in order to alert the operator in case
of excessive forward pressure. During no-load or normal operations,
there will be no indication. In case of overload, the LED will give a
red signal. In this case the tool must be disengaged. If the red signal
is disregarded for a longer period of time, the tool will be switched of
automatically by the electronic device. After disengagement and
switching the tool switch to off and on again drilling may continue.
Thermal: The motor is protected from destruction by a thermal element in case
of continuous overload. In this case, the engine will stop
automatically. It may be put back into operations after a cooling
period of approx. 2 min, depending on the degree of overheating of
the motor winding and ambient temperature.
Safety clutch
The slip clutch is designed to absorb shocks and excessive loads. It is designed
as an auxiliary means and not an absolute protection. Therefore, care must be
taken during drilling. To maintain the operability, the clutch should slip for max. 2
seconds. After excessive wear the clutch must be exchanged by an authorized
service point.
Do not loosen a jammed drill bit by switching the tool off and on. This will
cause a premature wear of the clutch.
Breaking of a segment
In case that a diamond segment, parts of the reinforcement or similar loosens
during drilling and the drill bit thereby gets jammed, stop working on this borehole
and drill a hole with the same center and a 15 to 20 mm greater diameter.
Do not try to finish drilling with another drill bit of the same diameter!
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