Working Advice - Bosch Professional GDR Manual Original

OBJ_BUCH-2873-001.book Page 8 Wednesday, April 20, 2016 8:54 AM
8 | English
Gear selection, mechanical
 Actuate the gear selector 3 only when the machine is at
a standstill.
Two speed ranges can be preselected with the gear selector
3.
Gear I:
Low speed range; for screwdriving or working with large drill-
ing diameter.
Gear II:
High speed range; for working with small drilling diameter.
If the gear selector 3 cannot be pushed through to the stop,
lightly turn the drill chuck with drill bit.
Switching On and Off
To start the machine, press the On/Off switch 8 and keep it
pressed.
The power light 9 lights up when the On/Off switch 8 is slightly
or completely pressed, and allows the work area to be illumi-
nated when lighting conditions are insufficient.
To switch off the machine, release the On/Off switch 8.
To save energy, only switch the power tool on when using it.
Adjusting the Speed
The speed of the switched-on power tool can be variably ad-
justed, depending on how far the On/Off switch 8 is pressed.
Light pressure on the On/Off switch 8 results in a low rotation-
al speed. Further pressure on the switch results in an increase
in speed.
Temperature Dependent Overload Protection
In normal conditions of use, the power tool cannot be over-
loaded. If the power tool is overloaded or not kept within the
permitted battery temperature range, the power output is re-
duced or the power tool is switched off. The power tool will
not run at full power output again until the permitted battery
temperature has been reached.
Reference Values for Maximum Screw/Bolt Tightening Torques
Calculated from the tensional cross-section; utilization of the yield point 90 % (with friction coefficient μ
measure, always check the tightening torque with a torque wrench.
Property Classes Standard Screws/Bolts
according to DIN 267
3.6
M 6 2.71
M 8 6.57
M 10
M 12 22.6
M 14
M 16
1 609 92A 2SM | (20.4.16)

Working Advice

 Apply the power tool to the screw/nut only when it is
The torque depends on the impact duration. The maximum
achieved torque results from the sum of all individual torques
achieved through impact. The maximum torque is achieved
after an impact duration of 6–10 seconds. After this dura-
tion, the tightening torque is increased only minimally.
The impact duration is to be determined for each required
tightening torque. The actually achieved tightening torque is
always to be checked with a torque wrench.
Screw Applications with Hard, Spring-loaded or Soft Seat
A test in which the achieved torques in an impact series are
measured and transferred to a diagram will produce the curve
of a torque characteristic. The height of the curve corre-
sponds with the maximum reachable torque, and the steep-
ness indicates the duration in which this is achieved.
A torque gradient depends on the following factors:
– Strength properties of the screws/nuts
– Type of backing (washer, disc spring, seal)
– Strength properties of the material being screwed/bolted
– Lubrication conditions at the screw/bolt connection
The following application cases result accordingly:
– A hard seat is given for metal-to-metal screw applications
– A spring-loaded seat is given for metal-to-metal screw ap-
– A soft seat is given for screw applications, e. g., metal on
For a spring-loaded seat as well as for a soft seat, the maxi-
mum tightening torque is lower than for a hard seat. Also, a
clearly longer impact duration is required.
4.6 5.6 4.8
3.61 4.52 4.8
8.7 11 11.6
13 17.5 22 23
30 37.6 40
36 48 60 65
55 73 92 98
switched off. Rotating tool inserts can slip off.
together
with the use of washers. After a relatively short impact du-
ration, the maximum torque is reached (steep characteris-
tic curve). Unnecessary long impact duration only causes
damage to the machine.
plications, however with the use of spring washers, disc
springs, studs or screws/nuts with conical seat as well as
when using extensions.
wood or when using lead washers or fibre washers as back-
ing.
6.6 5.8 6.8 6.9
5.42 6.02 7.22 8.13
13.1 14.6 17.5 19.7
26 29 35 39
45 50 60 67
72 79 95 107
110 122 147 165
= 0.12). As a control
total
High-strength Bolts
8.8 10.9 12.9
9.7 13.6 16.2
23 33 39
47 65 78
80 113 135
130 180 215
196 275 330
Bosch Power Tools