English - 5
Press both releasebuttons and the belt clip 5 will
automatically spring out. To remove the belt
clip 5 remove the complete fixture by unscrewing
the fastening screw.
By fixing the belt clip 5 make sure that the fasten-
ing screw is fully tighten.
The torque depends on the impact duration. The
maximum achieved torque results from all indi-
vidually achieved torques. The maximum torque
is achieved after an impact duration of 6 to
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 dia-
gram, the result is the curve of a torque charac-
teristic. The height of the curve corresponds 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 bolts /nuts
– Type of backing (washer, disc spring, seal)
– Strength properties of the material being
screwed/bolted together
– Lubrication conditions at the screw /bolt con-
nection
The following application cases result accord-
ingly:
A hard seat is given for metal to metal screw ap-
plications with the use of washers. After a rela-
tively short impact duration, the maximum torque
is reached (steep characteristic curve). Unneces-
sary 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 bolts /nuts
with conical seat as well as when using exten-
sions.
A soft seat is given for screw applications, e. g.,
metal on wood or when using lead washers or fi-
bre 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.
Calculated from the tensional cross-section; utilization of the yield point 90 %
(with friction coefficient µ
total
= 0.12)
☞
As a control measure, always check the tightening torque with a torque wrench.
Operating Instructions
Reference Values for Maximum Bolt Tightening Torques in Nm
Property Classes
according to DIN 267
Standard Bolts
High-strength
Bolts
new 3.6
4.6
5.6
4.8
6.6
5.8
6.8
6.9
8.8
10.9
12.9
until now 4 A
4 D
5 D
4 S
6 D
5 S
6 S
6 G
8 G
10 K 12 K
M 6
2.71
3.61
4.52
4.8
5.42
6.02
7.22
8.13
9.7
13.6
16.2
M 8
6.57
8.7
11
11.6
13.1
14.6
17.5
19.7
23
33
39
M 10
13
17.5
22
23
26
29
35
39
47
65
78
M 12
22.6
30
37.6
40
45
50
60
67
80
113
135
M 14
36
48
60
65
72
79
95
107
130
180
215
2 609 140 255.book Seite 5 Montag, 13. September 2004 9:55 09
17 • 2 609 140 255 • 04.09
