Self-Study Program
58
367_114
Certain adaption conditions have to be met so that
adaptions can be performed:
– The ATF temperature must be between 66 °C and
110 °C.
– Engine load must be within a defined range (very
low engine load or low accelerator pedal angle).
– No faults registered in the fault memory of the
gearbox control unit
– A defined driving state (e.g. certain adaptions
are only performed when the vehicle is
stationary and when the engine is running at
idling speed)
– Good road conditions (no uphill gradient or
downhill gradient, straight road)
The gearbox adaption status is established over
a prolonged period of time in service. A further
feature of the gearbox control unit is that the
adaption frequency is reduced with increasing
mileage. This means that the adaption frequency
of a gearbox with low mileage or with cancelled
adaption values is very high. On the other hand,
gearboxes with high mileage has longer adaption
intervals.
Gearbox control unit
A
Pre-filling
Quick filling time
(quick filling)
Filling pressure
B
Shift pressure
C
Holding pressure
The following aspects of the gearshift sequence are
adapted:
– Quick filling time (pre-filling)
– Filling pressure (pre-filling)
– Shift pressure (engaging and disengaging
clutch)
– Holding pressure
Explanation / definition of the individual adaption
ranges:
Quick filling time = period during which increased
pressure is applied to the clutch in order to engage
the clutch assembly and fill the clutch cylinder
chamber.
Filling pressure = pressure which is required to
compress the clutch plate assembly to the point
where the clutch just comes into engagement
but a significant amount of this torque is still
not transmitted.
Shift pressure = pressure which acts during the slip
phase.
Holding pressure = pressure required to keep the
clutch securely closed.
Adaptions are made during gearshift cycles and
when the vehicle is stationary with the engine
running at idling speed.
Legend
n_mot = engine speed
n_t = turbine speed
m_mot = engine torque
P_zu = engaging clutch
P_ab = disengaging clutch
t = time
A, B, C = adaption range
Upshift under acceleration sequence