BA 5080 en 06/2014
6.10
Screwconnection classes, tightening torques and initialtensioning forces
6.10.1
Screwconnection classes
The specified screw connections are to be fastened applying the tightening torques specified observing
the table below.
NOTICE
Material damage
Risk of damage to the bolts and/or mating threads through incorrect tightening.
Foundation bolts, hub bolts and bearingcover bolts must always be tightened in accordance with
screwconnection class "C".
Table 7:
Screwconnection classes
Fastening of
Screw-connection
class
Tightening procedure
Gear unit
Motor*
C
– Hydraulic tightening with mechanical screwdriver
– Hydraulic tightening with mechanical screwdriver
– Tightening with precision mechanical screwdriver
with dynamic torque measuring
D
– Torque-controlled tightening with mechanical screwdriver
Protective hood
E
– Tightening with pulse screwdriver or impact wrench
without adjustment checking device
– Tightening by hand, using a spanner without torque
measuring device
*
)
The tightening torques applying to these addon parts can be found in the instructions supplied by the
manufacturers of the parts.
6.10.2
Tightening torques and initialtensioning forces
The tightening torques apply to friction coefficients of μ
total
= 0.14.
The friction coefficient μ
total
= 0.14 applies here to lightly oiled steel bolts, blackannealed or phosphatised
and dry, cut mating threads in steel or cast iron. Lubricants which alter the friction coefficient must not be
used and may overload the screw connection.
Table 8:
Initialtensioning forces and tightening torques for screw connections of strength classes
8.8; 10.9; 12.9
with a common friction coefficient of
μ
total
= 0.14
Nominal
thread
diameter
Strength
class
of the bolt
Initial-tensioning force
for screw-connection classes
from table 7
Tightening torque
for screw-connection classes
from table 7
C
D
E
C
D
E
d
mm
F
M min.
N
M
A
Nm
M10
8.8
18000
11500
7200
44.6
38.4
34.3
10.9
26400
16900
10600
65.4
56.4
50.4
12.9
30900
19800
12400
76.5
66.0
58.9
M12
8.8
26300
16800
10500
76.7
66.1
59.0
10.9
38600
24700
15400
113
97.1
86.6
12.9
45100
28900
18100
132
114
101
