Starting Operation; Working Advice - Bosch GBH Professional 3-28 DRE Notice Originale

OBJ_BUCH-770-007.book Page 18 Wednesday, October 2, 2013 10:37 AM
18 | English
– Position the the guide pipe 27 of the dust extraction at-
tachment in its holding fixture in such a manner that the
head of the dust extraction attachment faces against the
surface to be drilled. Do not slide the guide pipe 27 further
over the telescopic pipe 25 of the dust extraction attach-
ment than required, so that as much as possible of the
scale 25 on the telescopic pipe remains visible.
– Retighten the wing bolt 26 again. Loosen the clamping screw
23 on the depth stop of the dust extraction attachment.
– Move the depth stop 24 on the telescopic pipe 25 in such
a manner that the clearance X shown in the figure corre-
sponds with the required drilling depth.
– Tighten the clamping screw 23 in this position.
Operation

Starting Operation

 Observe correct mains voltage! The voltage of the pow-
er source must agree with the voltage specified on the
nameplate of the machine. Power tools marked with
230 V can also be operated with 220 V.
Setting the operating mode
The operating mode of the power tool is selected with the
mode selector switch 9.
Note: Change the operating mode only when the machine is
switched off! Otherwise, the machine can be damaged.
– To change the operating mode, push the release button 8
and turn the mode selector switch 9 to the requested posi-
tion until it can be heard to latch.
Position for hammer drilling in concrete or
stone
Position for drilling without impact in wood,
metal, ceramic and plastic as well as for
screwdriving
Vario-Lock position for adjustment of the
chiselling position
The mode selector switch 9 does not latch in
this position.
Position for chiselling
Reversing the rotational direction
The rotational direction switch 13 is used to reverse the rota-
tional direction of the machine.
 Actuate the rotational direction switch 13 only when
the machine is at a standstill.
1 619 92A 06A | (2.10.13)
Right rotation: Turn the rotational direction switch 13 to
the stop in position .
Left rotation: Turn the rotational direction switch 13 to
the stop in position .
Set the direction of rotation for hammer drilling, drilling and
chiselling always to right rotation.
Switching On and Off
– To start the machine, press the On/Off switch 7.
– To switch off the machine, release the On/Off switch 7.
To save energy, only switch the power tool on when using it.
Setting the Speed/Impact Rate
The speed/impact rate of the switched on power tool can be
variably adjusted, depending on how far the On/Off switch 7
is pressed.
Light pressure on the On/Off switch 7 results in low speed/im-
pact rate. Further pressure on the switch increases the
speed/impact rate.
Safety Clutch
 If the tool insert becomes caught or jammed, the drive
to the drill spindle is interrupted. Because of the forces
that occur, always hold the power tool firmly with both
hands and provide for a secure stance.
 If the power tool jams, switch the machine off and loosen
the tool insert. When switching the machine on with the
drilling tool jammed, high reaction torques can occur.

Working Advice

 Before any work on the machine itself, pull the mains
plug.
Changing the Chiselling Position (Vario-Lock)
The chisel can be locked in 36 positions. In this manner, the
optimum working position can be set for each application.
– Insert the chisel into the tool holder.
– Turn the mode selector switch 9 to the "Vario-Lock" posi-
tion (see "Setting the operating mode", page 18).
– Turn the tool holder to the desired chiselling position.
– Turn the mode selector switch 9 to the "chiselling" posi-
tion. The tool holder is now locked.
– For chiselling, set the rotation direction to right rotation.
Inserting Screwdriver Bits (see figure L)
 Apply the power tool to the screw/nut only when it is
switched off. Rotating tool inserts can slip off.
To work with screwdriver bits, a universal bit holder 28 with
SDS-plus shank (accessory) is required.
– Clean the shank end of the adapter shank and apply a light
coat of grease.
– Insert the universal bit holder with a turning motion into
the tool holder until it automatically locks.
– Check the locking effect by pulling the universal bit holder.
– Insert a screwdriver bit into the universal bit holder. Use
only screwdriver bits that match the screw head.
– Turn the mode selector switch 9 to the "drilling" position.
– To remove the universal bit holder, pull the locking sleeve
5 toward the rear and remove the universal bit holder 28
out of the tool holder.
Bosch Power Tools