GF27.60-P-3009AHK Engage Gear Range, Function

GF27.60-P-3009AHK Engage Gear Range, Function
- TRANSMISSION 722.904 /906 /907 /999 in MODEL 171.4 as of Model Year 09 /modification year 08 model refinement package

Function requirements for gear range engagement, general

^ Circuit 87 ON
^ Circuit 61 (engine running)

Gear range engagement, general

Each gear change is triggered by the fully integrated transmission control system. In the process one component group is assigned to each shift operation.

One component group consists of the respective control solenoid valve, the regulating valve involved, the responsible shift valve and the necessary multi-disk brake or necessary multi-disk clutch.

The pressure in the multidisk brake or multidisk clutch to be engaged is increased constantly while at the same time the pressure in the multidisk brake or multidisk clutch to be disengaged is reduced. In the process a flowing transition is involved, but nevertheless the components affected are actuated directly and as a result enable downshifting via several gears.

Gear range engagement, function sequence

Shift operation N to D (1st gear)

When the center shifter console is in position "N", multidisk brake B3 and multidisk clutch K3 are engaged. Shifting from position "N" into position "D" on the electronic selector lever module control unit (N15/5) means that the supply to the multidisk brake B2 is enabled by the selector valve. The fully integrated transmission control unit (VGS) (Y3/8n4) actuates brake control solenoid valve B2 (VGS) (Y3/8y6) and multidisk brake B2 is filled with oil.

From the rpm difference (actual slip) of engine speed to turbine speed the fully integrated transmission control unit detects whether the multidisk brake B2 is filled. The brake control solenoid valve B2 (VGS) actuates the regulating valve B2 or BR which converts the applied working pressure into shift pressure and passes it on to the multi-disk brake B2

In the fully integrated transmission control unit (VGS), the required slip (specified slip) is stored for the respective gear. To match this, the control pressure on regulating valve B2 or BR is changed via brake control solenoid valve B2 (VGS). The shift pressure produced by the regulating valve B2/BR depends on the geometry of the regulating valve B2/BR. The pressure in multidisk brake B2 is changed until the specified slip stored in the fully integrated transmission control unit (VGS) is reached.