Volkswagen 2004 Jetta, Руководство по введению

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38
Engines
The new Crankshaft Torsional Cancellation
(CTC) toothed belt sprocket reduces
camshaft vibration and the forces acting on
the toothed belt.
Function
The toothed belt sprocket is positioned on
the crankshaft at TDC of cylinder 1, as
shown below. When the cycle begins,
forces acting on the toothed belt are
reduced by the elliptical shape of the
toothed belt sprocket. The flat side of the
sprocket gear allows a slight slackening of
the toothed belt.
Toothed Belt Drive
As with all 4-cylinder in-line engines, the
timing gear drives a toothed belt that drives
the exhaust camshaft.
The toothed belt tensioning system has
been modified to meet the demands placed
on the toothed belt drive by the turbo,
including:
• Higher valve spring pressures
• Turbo-related valve timing associated
with the 42
° crank angle adjustment
range of the continuous variable valve
timing on the intake camshaft
• High-pressure oil pump drive from a
triple cam on the intake camshaft
The modification is an elliptical toothed belt
sprocket on the crankshaft.
D
1
D
2
D
2
>D
1
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