Self-Study Program

1st gear in tiptronic mode

(with engine braking effect)

Gearbox subassemblies

367_024

367_025

Shift elements: clutch K1 - brake B2

The engine braking effect can be utilised in 1st in

special driving situations - e.g. on steep downhill

gradients - by selecting 1st gear in tiptronic mode

(B2 closed). The torque curve is as described for

1st gear (on previous page).

The engine braking effect can only be utilised in

1st gear by closing brake B2. Brake B2 locks the

planet carrier PT2 like freewheel F. Unlike F,

however, B2 holds PT2 stationary in both directions

of rotation. This is necessary in order to engage

reverse and utilise the engine braking effect in

1st gear.

2nd gear i = 2.370

shift elements: clutch K1 - brake B1

The turbine shaft drives ring gear H1 of the

primary planetary gear set. Ring gear H1 drives

the planetary gears P1, which revolve around the

stationary sun gear S1.

Planet carrier PT1 is driven in this way.

Clutch K1 connects PT1 to sun gear S3, and thus

introduces torque into the secondary planetary

gear set.

Brake B1 locks the large sun gear S2 in place.

Torque is transmitted from sun gear S3 to the

short planetary gears P3 and, in turn, to the

long planetary gears P2.

The long planetary gears P2 roll around the

stationary sun gear S2 and drive ring gear H2,

which is connected to the gearbox output shaft.