Bosch GSB 20-2 RET Original Operating Instructions page 12

OBJ_BUCH-129-002.book Page 12 Tuesday, October 23, 2007 2:57 PM
12 | English
Adjusting the Speed/Impact Frequency
(GSB 20-2 RE/GSB 20-2 RCE/GSB 20-2 RET)
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.
Preselecting the Speed/Impact Frequency
(GSB 20-2 RE)
With the dial control for speed preselection 8,
the required speed/impact frequency can be pre-
selected even during operation.
The required speed/impact frequency depends
on the material and the working conditions, and
can be determined through practical testing.
Electronic Speed Preselection
(GSB 20-2 RCE/GSB 20-2 RET)
With the speed dial for electronic speed prese-
lection 3, the required speed/impact frequency
can be selected even if the machine is running.
The required speed/impact frequency depends
on the material and the working conditions, and
can be determined through practical testing.
Constant Electronic Control
(GSB 20-2 RCE/GSB 20-2 RET)
The constant electronic control keeps the prese-
lected speed and impact rate nearly constant be-
tween no-load and load conditions.
Electronic Torque Limitation/Speed Preselec-
tion (Torque Control) (GSB 20-2 RET)
Drilling with speed preselection: Set
the selector switch 4 to the "Drilling"
symbol. The required speed can be
selected with the speed dial 3; it can
also be adjusted during operation.
1 609 929 M40 | (23.10.07)
Screwdriving with torque limitation:
Set the selector switch 4 to the
"Screwdriving" symbol. The effective
torque at the drill spindle can be vari-
able adjusted with the dial control 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 drill-
ing tool no longer rotates. If the load on the ma-
chine 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.
For screwdriving without torque lim-
itation, turn the speed dial 3 to the
right stop. This setting is required,
when the torque in position III is not
sufficient.
Working Instructions
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 un-
til 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 sharp-
ened with the drill bit sharpener (see accesso-
ries).
Bosch Power Tools