Audi A3 Sportback, Сервисная инструкция, Страница: 25 / 60

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Decoupled final drive sprocket
The higher torsional irregularity in the crankshaft of the turbo engine at the bottom end of the RPM range
results in much greater chain forces in the balancer shaft chain drive. The oscillation angle of 2° crank angle in
the turbo engine is significantly higher than the relative oscillation angle of 0.8° crank angle in the naturally
aspirated engine. The sudden load on the chain drive would subject the chain to increased wear unless
measures are taken. For this reason, bow springs have been integrated into the sprocket wheel hub. They
decouple the input shaft of the balancer shaft module from the crankshaft. This device functions similarly to
a dual-mass flywheel.
332_022
Diamond coated disc
Hub
Plain bearing
Bow spring (2x)
Friction disc
Diaphragm spring
Cover disc
Sprocket wheel
Chain load with and without decoupling
Chain load without decoupling
Chain load with decoupling
332_016
Cha
in
for
c
e
i
n
(
N
)
Critical range
(zero transitions)
Ch
ai
n fo
rc
e
i
n
(
N
)
Tensile force
Maximum value
Mean value
Minimum value
Tensile force
Maximum value
Mean value
Minimum value