Ober ERVIT11D Mode D'emploi page 9

CLUTCH
The gear clutch is mounted on the tool-bearing spindle in the front part of the screwdriver.
It has the function of transmitting to the bit, and therefore to the screw, only part of the torque
that may be produced by the screwdriver so as to ensure optimal screw-tightening conditions.
It also makes it possible to maintain a highly constant level of torque when tightening screws
in sequence. When the resistance offered by the screw has reached the maximum level
allowed by the clutch setting, the teeth skip to prevent the torque transmitted from exceeding
the preset level. The range of clutch settings is determined by the spring (1) that locks the
toothed disks (2). Different springs are available, each one covering a range of torque values
as indicated in table 2. Note that the ranges of torque settings are overlapping, i.e. certain
torque values may be obtained with different springs. When choosing a spring, it is always
advisable to make sure that the levels of torque you wish to obtain are situated towards the
middle of its range of settings. With the same screwdriver and the same spring, the effective
torque applied to the screw strongly depends on the degree of rigidity of the joint. Other conditions being equal, pliable or
elastic joints may determine a considerable reduction in torque. All the values shown in the diagrams and tables refer to
rigid joints. If the requested torque is not included in the setting range of the equipped clutch, you should choose a fitting
one (see table 2). It's clear that the torque it self can't exceed the characteristic value indicated in table 1.
Table 2 RANGE OF CLUTCH SETTINGS
Clutch group Spring code Spring colour
7311146 5080111
7311141 5080110
7311142 5080112
7311143 5080114
7311144 5080116
7311145 5080118
green
white
yellow
plain
red
black
Nm 0 1 2 3 4 5 6 7 8
Torque
9 10 11 12 13 14 15 16 17 18