Working Advice - Bosch Professional GDS 18 E Manual Original

OBJ_BUCH-544-005.book Page 11 Tuesday, September 13, 2016 10:05 AM
Reversing the rotational direction (see figure A)
The rotational direction switch 7 is used to reverse the rota-
tional direction of the machine. However, this is not possible
with the On/Off switch 5 actuated.
– Right rotation:
Press the rotational direction switch 7 rightward
to the stop.
– Left rotation:
Press the rotational direction switch 7 leftward
to the stop.
Switching On and Off
– To start the machine, press the On/Off switch 5 and keep
it pressed.
– To switch off the machine, release the On/Off switch 5.
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 5 is pressed.
Light pressure on the On/Off switch 5 results in a low rotation-
al speed. Further pressure on the switch results in an increase
in speed.
Preselecting the Speed
The required speed can be preselected with the thumbwheel
6 (also while running).

Working Advice

 Before any work on the machine itself, pull the mains
plug.
 Apply the power tool to the screw/nut only when it is
switched off. Rotating tool inserts can slip off.
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 3–5 seconds. After this duration,
the tightening torque is increased only minimally.
However, the transmission housing heats up noticeably.
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
M6 2.71
M8 6.57
M10 13
M12 22.6
M14 36
M16 55
M18 75
M20 107
Bosch Power Tools
Note: The consequences of excessive heating-up are high
wear of all hammer mechanism components and a high re-
quirement of lubricant.
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
When in a test, the achieved torques in an impact series are
measured and transferred into a diagram, resulting in 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
together
– Lubrication conditions at the screw/bolt connection
The following application cases result accordingly:
– A hard seat is given for metal-to-metal screw applications
with the use of washers. After a relatively short impact
duration, the maximum torque is reached (steep charac-
teristic curve). Unnecessary long impact duration only
causes damage to the machine.
– A spring-loaded seat is given for metal-to-metal screw
applications, however with the use of spring washers, disc
springs, studs or screws/nuts with conical seat as well as
when using extensions.
– A soft seat is given for screw applications, e. g., metal on
wood or when using lead washers or fibre washers as backing.
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 6.6 5.8
3.61 4.52 4.8 5.42 6.02
8.7 11 11.6 13.1 14.6
17.5 22 23 26 29
30 37.6 40 45 50
48 60 65 72 79
73 92 98 110 122
101 126 135 151 168
143 178 190 214 238
English | 11
= 0.12). As a control
total
High-strength Bolts
6.8 6.9 8.8 10.9 12.9
7.22 8.13 9.7 13.6 16.2
17.5 19.7 23 33 39
35 39 47 65 78
60 67 80 113 135
95 107 130 180 215
147 165 196 275 330
202 227 270 380 450
286 320 385 540 635
1 609 92A 2CX | (13.9.16)