User Guide

Owing to its integral
spring/damper
system, the DMF
almost entirely ab-
sorbs this torsional
vibration. The result:
very good vibration
damping.
Torque is transferred via the flange. The flange is riveted
to the secondary mass with its wings sitting between the
arc springs.
The secondary mass helps to increase the mass moment
of inertia on the gearbox side. Vents ensure heat is
dissipated eciently. As the DMF has an integral spring/
damper system, a rigid clutch disc without a torsion
damper is normally used.
The periodic combustion cycles of a 4-stroke engine
create torque fluctuations which causes torsional vibra-
tion to be passed down the drive train. The resulting noise
and vibration, such as gear rattle, body boom and load
change vibration, results in a decrease in both cabin
and driving comfort. The objective when developing the
DMF was therefore to isolate as much of the drive train
as possible from the torsional vibration caused by the
engine’s rotating mass.
Standard DMF
A standard DMF consists of the primary mass and the
secondary mass.
The two decoupled masses are connected via a spring/
damper system and supported by a deep groove ball bearing
or plain bearing so they can rotate against each other.
The primary mass with starter ring gear is driven by the
engine and tightly bolted to the cranksha. It encloses,
together with the primary cover, a cavity which forms the
arc spring channel.
At the heart of the spring/damper system are the arc
springs. They sit in guides in the arc spring channels
and cost-eectively full the requirements of an “ideal”
torsion damper. The guides ensure correct guidance of
the springs during operation and the grease around the
springs reduces wear between themselves, the guides
and the channels.
. Why DMF?
1 Starter ring gear
2 Primary mass
3 Arc springs
4 Plain bearing
 Dual mass flywheel – DMF
2 Dual mass flywheel – DMF
. Design
1
2
3
4
5
6
7
5 Flange
6 Primary cover (cross section)
7 Secondary mass