Bosch GSB Professional 21-2 Manual Original página 17

OBJ_BUCH-909-004.book Page 17 Wednesday, January 13, 2016 11:44 AM
Right rotation: For drilling and driving in screws, push the ro-
tational direction switch 5 downward on the left side and at
the same time upward on the right side.
Left rotation: For loosening and unscrewing screws and
nuts, push the rotational direction switch 5 upward on the left
side and at the same time downward on the right side.
Setting the operating mode
Drilling and Screwdriving
Set the selector switch 2 to the "Drilling" symbol.
Impact Drilling
Set the selector switch 2 to the "Impact drilling"
symbol.
The selector switch 2 engages noticeably and can also be ac-
tuated with the machine running.
Gear selection, mechanical
 The gear selector 9 can be actuated on machines run-
ning at low speed. However, this should not be done
when the machine is stopped, at full load or running at
maximum speed.
Two speed ranges can be preselected with the gear selector 9.
Gear I:
Low speed range; for working with large drill-
ing diameter or for driving in screws.
Gear II:
High speed range; for working with small
drilling diameter.
If the gear selector 9 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 7 and keep it
pressed.
To lock the pressed On/Off switch 7, press the lock-on button
6.
To switch off the machine, release the On/Off switch 7 or
when it is locked with the lock-on button 6, briefly press the
On/Off switch 7 and then release it.
To save energy, only switch the power tool on when using it.
Safety Clutch
To limit high reaction torque, the pow-
er tool is equipped with a safety clutch
(Anti-Rotation).
 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.
Bosch Power Tools
 If the power tool jams, switch the machine off and loos-
en the tool insert. When switching the machine on with
the drilling tool jammed, high reaction torques can oc-
cur.
Adjusting the Speed/Impact Frequency
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.
Preselecting the Speed/Impact Frequency
With the thumbwheel for speed preselection 8, the required
speed/impact frequency can be preselected even during op-
eration.
The required speed/impact frequency depends on the mate-
rial and the working conditions, and can be determined
through practical testing.
Electronic Speed Preselection (GSB 21-2 RCT)
With the thumbwheel for electronic speed preselection 3, the
required speed/impact frequency can be selected even if the
machine is running.
The required speed/impact frequency depends on the mate-
rial and the working conditions, and can be determined
through practical testing.
Constant Electronic Control (GSB 21-2 RCT)
The constant electronic control keeps the preselected speed
and impact rate nearly constant between no-load and load
conditions.
Electronic Torque Limitation/Speed Preselection
(Torque Control) (GSB 21-2 RCT)
Drilling with speed preselection: Set the se-
lector switch 4 to the "Drilling" symbol. The re-
quired speed can be selected with the thumb-
wheel 3; it can also be adjusted during
operation.
Screwdriving with torque limitation: Set the
selector switch 4 to the "Screwdriving" sym-
bol. The effective torque at the drill spindle can
be variable adjusted with the thumbwheel 3
during operation:
I=low torque, III=high torque.
The maximum speed is automatically adapted
to the adjusted torque.
If the preselected torque is reached during screwdriving, the
machine switches off; the drilling tool no longer rotates. If the
load on the machine is then removed with the On/Off switch 7
still pressed, the drilling tool continues to run only at very low
speed for safety reasons.
After briefly releasing the On/Off switch 7, the next screw can
be driven in with the same torque.
English | 17
2 609 932 948 | (13.1.16)