User Manual

. Flange
At high engine speeds, the resulting centrifugal forces
press the arc springs to the outside against the guides
and the coils are disabled. Consequently, the arc spring
stiffens and spring action is partly lost. In order to maintain
sufficient spring action, straight pressure springs are
mounted in the flange. Owing to their lower mass and
mounting position on a smaller radius, these springs are
subject to a lower centrifugal force. Additionally, the
convex shape of the upper edge of the spring windows
helps to minimise friction. This ensures that neither
friction nor the effective spring rate will increase as
engine speeds go up.
Flange with friction clutch
When an attempt is made to adjust the engine speed
very quickly to the speed of the gearbox input shaft,
sudden peak loadings occur, so-called impacts. In this
way, for example, an impact may be caused by a sudden
engagement, leading to stalling of the engine. Here, the
arc springs are briefly fully compressed, leading to a
disproportionate increase in the loading on the flange.
In the case of rigid flanges and those with internal damping,
frequent impacts may lead to material deformation,
culminating in breakage of the flange wings.
One way to compensate for impacts and minimise material
damage is a flange with a friction clutch. In this case,
the flange is designed as a diaphragm spring. It is pre-
tensioned and positioned by two riveted retaining plates
with a thin friction lining. In cross-section, this forms a
fork-shaped fixture which allows slipping of the flange.
In the case of an impact, the flange can now rotate in
the retaining plates. The surplus energy is dissipated as
friction heat. In this way, the load on the flange wings is
minimised.
Note:
This overload protection is only designed for brief
peak loads in normal driving. Permanent overload-
ing, e.g. when towing an excessive trailer load or due
to performance enhancement (chip tuning), leads to
premature wear on the friction clutch. As a result, the
flange is able to transmit less and less engine torque.
In extreme cases, the transmission of force in the DMF
is reduced to such an extent that the transmittable en-
gine torque is no longer sufficient to drive the vehicle.
1 Spring aperture
2 Guides
3 Arc spring stop in the primary mass
4 Pressure spring
5 Flange
1 Flange
2 Retaining panel
3 Friction lining
3 DMF components
1
2
3
4
5
1
2
3
On the basis of this fai
lure symptom, the clutch is
often replaced, but that does not cure the malfunction
in the case of this defect. In order to avoid an incor-
rect diagnosis in the case of damage, the DMF should
also be inspected during the repair. If the bolt holes
in the primary and secondary mass are so oset that
they prevent removal of the crankshaft bolts, that
may indicate a defective flange with friction clutch.