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Tightening torque
Before tightening any screw, note the following:
The table below specifies the recommended standard tightening torque for oil-lubricated
screws with slotted or cross-recess head screws.
Dimension
The table below specifies the recommended standard tightening torque for oil-lubricated
screws with Allen head screws.
Dimension
M5
M6
M8
M10
M12
M16
M24
The table below specifies the recommended standard tightening torque for Molycote-
lubricated screws with Allen head screws.
Dimension
M8
M10
M12
3HAC026876-001 Revision: C
•
Determine whether a standard tightening torque or special torque is to be applied.
The standard torques are specified in the tables below. Any special torques are
specified in the Repair, Maintenance or Installation procedure descriptions. Any
special torque specified overrides the standard torque!
•
Use the correct tightening torque for each type of screw joint.
•
Only use correctly calibrated torque keys.
•
Always tighten the joint by hand, and never use pneumatical tools.
•
Use the correct tightening technique, that is do not jerk. Tighten the screw in a slow,
flowing motion.
•
Maximum allowed total deviation from the specified value is 10%!
Tightening torque (Nm)
Class 4.8, oil-lubricated
M2.5
0.25
M3
0.5
M4
1.2
M5
2.5
M6
5.0
Tightening torque
(Nm)
Class 8.8, oil-lubri-
cated
6
10
24
47
82
200
725
Tightening torque (Nm)
Class 10.9, Molycote-lubricated
28
55
96
7 Reference information
Tightening torque
Tightening torque
(Nm)
(Nm)
Class 10.9, oil-lubri-
Class 12.9, oil-lubri-
cated
cated
-
-
-
-
34
40
67
80
115
140
290
340
960
1150
Tightening torque (Nm)
Class 12.9, Molycote-lubricated
35
70
120
7.4. Screw joints
Continued
Continues on next page
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