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

GF27.60-P-3009AHI Engage gear range, function
- TRANSMISSION 722.930


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. This involves a flowing transition. Despite this the affected components are directly actuated and therefore enable shifting down through 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. When the electronic selector lever module control unit (N15/5) shifts from position "N" to position "D", the feed to 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.

The fully integrated transmission control unit uses the rpm difference (actual slip) between the engine speed and turbine speed to detect whether the multidisk brake B2 is full. 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.