Starting Operation; Working Advice - Bosch Professional GBH 3-28 DRE Manual Original

Operation

Starting Operation

Observe the mains voltage! The voltage of
the power source must correspond with the
data on the type plate of the machine.
Setting the Operating Mode
The operating mode of the power tool is se-
lected 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 position until it can be heard to
latch.
Position for hammer drilling in
concrete or stone
Position for drilling without im-
pact 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 rotational direction of the machine.
Actuate the rotational direction switch 13
only when the machine is at a standstill.
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
Bosch Power Tools
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.
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/impact 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 in-
terrupted. 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 switch-
ing the machine on with the drilling tool
jammed, high reaction torques can occur.

Working Advice

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" position (see "Setting the Operating
Mode", page 27).
Turn the tool holder to the desired chiselling
position.
Turn the mode selector switch 9 to the "chisel-
ling" position. The tool holder is now locked.
For chiselling, set the rotation direction to right
rotation.
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English | 27
1 619 929 E56 | (7.4.09)