Maintenance And Service; Maintenance And Cleaning - Bosch PROFESSIONAL GDR 10,8 V-LI Instructions D'emploi

OBJ_BUCH-223-002.book Page 17 Thursday, December 14, 2006 10:15 AM
Operating Instructions
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 max-
imum achieved torque results from the sum of all indi-
vidual torques achieved through impact. The
maximum torque is achieved after an impact duration
of 6–10 seconds. After this duration, 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
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 corresponds with the maximum
reachable torque, and the steepness indicates the
duration in which this is achieved.
Reference Values for Maximum Screw/Bolt Tightening Torques
Calculated from the tensional cross-section; utilization of the yield point 90 % (with friction coefficient
µ = 0.12). As a control measure, always check the tightening torque with a torque wrench.
total
Property Classes according to
DIN 267
M 6
M 8
M 10
M 12
Tips
Before screwing larger, longer screws into hard mate-
rials, it is advisable to predrill a pilot hole with the core
diameter of the thread to approx.
length.
Soft Grip
The gripping surface (soft grip) 5 reduces the danger
of slipping and thereby improves the grip on the
machine and the handling.
At the same time, the rubber coating achieves a vibra-
tion-reducing effect.
2 609 140 429 • 14.12.06
A torque gradient depends on the following factors:
• Strength properties of the screws/nuts
• Type of backing (washer, disc spring, seal)
• Strength
screwed/bolted together
• Lubrication conditions at the screw/bolt connec-
tion
The following application cases result accordingly:
• A hard seat is given for metal-to-metal screw
applications with the use of washers. After a rela-
tively short impact duration, the maximum torque is
reached (steep characteristic 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
maximum tightening torque is lower than for a hard
seat. Also, a clearly longer impact duration is required.
Standard Screws/Bolts
3.6 4.6 5.6 4.8 6.6
2.71 3.61 4.52 4.8 5.42 6.02 7.22 8.13 9.7
6.57 8.7 11 11.6 13.1 14.6 17.5 19.7 23
13 17.5 22 23 26
22.6 30 37.6 40 45

Maintenance and Service

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/ of the screw

Maintenance and Cleaning

3
Before any work on the machine (e. g., main-
tenance, tool change, etc.) as well as during
transport and storage, set the rotational
direction switch to the centre position. Unin-
tentional actuation of the On/Off switch can lead
to injuries.
For safe and proper working, always keep
the machine and ventilation slots clean.
When the battery is no longer operative, please refer
to an authorised after-sales service agent for Bosch
power tools.
properties of the material
High-strength
Bolts
5.8 6.8 6.9 8.8 10.9 12.9
13.6 16.2
33
29 35 39 47 65
50 60 67 80 113
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