Bosch GDR 12V-105 Extension Manual Original página 15

OBJ_BUCH-2895-001.book Page 15 Tuesday, July 19, 2016 12:52 PM
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
together
– Lubrication conditions at the screw/bolt connection
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 13
M 12 22.6
Tips
Before screwing larger, longer screws into hard materials, it is
advisable to predrill a pilot hole with the core diameter of the
2
thread to approx. / of the screw length.
3
Maintenance and Service
Maintenance and Cleaning
 Before any work on the machine itself (e. g. mainte-
nance, tool change, etc.) as well as during transport
and storage, remove the battery from the power tool.
There is danger of injury when unintentionally actuating
the On/Off switch.
 For safe and proper working, always keep the machine
and ventilation slots clean.
When the battery is no longer operative, please refer to an au-
thorised after-sales service agent for Bosch power tools.
After-sales Service and Application Service
Our after-sales service responds to your questions concern-
ing maintenance and repair of your product as well as spare
parts. Exploded views and information on spare parts can al-
so be found under:
www.bosch-pt.com
Bosch's application service team will gladly answer questions
concerning our products and their accessories.
Bosch Power Tools
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 du-
ration, the maximum torque is reached (steep characteris-
tic curve). Unnecessary long impact duration only causes
damage to the machine.
– A spring-loaded seat is given for metal-to-metal screw ap-
plications, 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 back-
ing.
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
3.61 4.52 4.8 5.42
8.7 11 11.6 13.1
17.5 22 23 26
30 37.6 40 45
In all correspondence and spare parts orders, please always
include the 10-digit article number given on the nameplate of
the product.
Great Britain
Robert Bosch Ltd. (B.S.C.)
P.O. Box 98
Broadwater Park
North Orbital Road
Denham
Uxbridge
UB 9 5HJ
At www.bosch-pt.co.uk you can order spare parts or arrange
the collection of a product in need of servicing or repair.
Tel. Service: (0344) 7360109
E-Mail: boschservicecentre@bosch.com
Ireland
Origo Ltd.
Unit 23 Magna Drive
Magna Business Park
City West
Dublin 24
Tel. Service: (01) 4666700
Fax: (01) 4666888
= 0.12). As a control
total
High-strength Bolts
5.8 6.8 6.9 8.8
6.02 7.22 8.13 9.7
14.6 17.5 19.7 23
29 35 39 47
50 60 67 80
1 609 92A 2N7 | (19.7.16)
English | 15
10.9 12.9
13.6 16.2
33 39
65 78
113 135