Bosch Professional GSB 780 Manual Original página 23

Two speed ranges can be preselected with the
gear selector 7.
Gear I:
Low speed range; for working with
large drilling diameter or for driv-
ing in screws.
Gear II:
High speed range; for working with
small drilling diameter.
If the gear selector 7 cannot be fully engaged,
lightly rotate the drive spindle with the drill bit
by twisting the drill chuck.
Switching On and Off
To start the machine, press the On/Off switch 6
and keep it pressed.
To lock the pressed On/Off switch 6, press the
lock-on button 4.
To switch off the machine, release the On/Off
switch 6 or when it is locked with the lock-on
button 4, briefly press the On/Off switch 6 and
then release it.
Safety Clutch
To limit dangerous reaction torque, the machine
is equipped with a safety clutch (anti-rotation).
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.
Adjusting the Speed/Impact Frequency
The speed/impact rate of the switched on pow-
er tool can be variably adjusted, depending on
how far the On/Off switch 6 is pressed.
Light pressure on the On/Off switch 6 results in
low speed/impact rate. Further pressure on the
switch increases the speed/impact rate.
Bosch Power Tools
Preselecting the Speed/Impact Frequency
With the thumbwheel for speed preselection 5,
the required speed/impact frequency can be
preselected even during operation.
The required speed/impact frequency depends
on the material and the working conditions, and
can be determined through practical testing.
Working Advice
Apply the power tool to the screw/nut only
when it is switched off. Rotating tool inserts
can slip off.
Tips
After longer periods of working at low speed, al-
low the machine to cool down by running it for ap-
prox. 3 minutes at maximum speed with no load.
For drilling in tiles, set the selector switch 2 to
the "Drilling" symbol. Do not switch over to the
symbol "Impact Drilling" or work with impact
until after drilling through the tile.
Use carbide tipped drill bits when working in
concrete, masonry and brick wall.
For drilling in metal, use only perfectly sharp-
ened HSS drill bits (HSS=high-speed steel). The
appropriate quality is guaranteed by the Bosch
accessories program.
Twist drills from 2.5–10 mm can easily be
sharpened with the drill bit sharpener (see ac-
cessories).
Maintenance and Service
Maintenance and Cleaning
Before any work on the machine itself, pull
the mains plug.
For safe and proper working, always keep
the machine and ventilation slots clean.
If the machine should fail despite the care taken
in manufacturing and testing procedures, repair
should be carried out by an after-sales service
centre for Bosch power tools.
In all correspondence and spare parts order,
please always include the 10-digit article
number given on the type plate of the machine.
English | 23
2 609 932 762 | (2.3.10)