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

GF27.60-P-3009AHT Engage Gear Range, Function
- TRANSMISSION 722.931 in MODEL 221.074 /174, 216.374

Function requirements for Engage gear range, general

^ Circuit 87 ON
^ Circuit 61 (engine running)

Engage gear range, 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.

Function sequence for engage gear range

Shift operation N to D (1st gear)

In position "N" of the DIRECT SELECT gear selector switch (S16/13), multidisk brake B3 and multidisk clutch K3 are engaged. When the intelligent servo module for DIRECT SELECT (A80) shifts from position "N" to position "D", the feed to multidisk brake B2 is opened by the selector valve. The fully integrated transmission control unit (VGS) (Y3/8n4) actuates brake control solenoid valve B2 (Y3/8y6) and multidisk brake B2 is filled with oil. The rpm difference (actual slip) between the engine speed and turbine speed enables the fully integrated transmission control unit (VGS) to recognize whether the multidisk brake B2 is full. The brake control solenoid valve B2 actuates the regulating valve B2 or BR which converts the applied working pressure into shift pressure and passes it on to the multidisk brake B2

In the fully integrated transmission control unit (VGS), the required slip (specified slip) is stored for the respective gear. The control pressure on regulating valve B2 or BR is changed via brake control solenoid valve B2 depending on this. 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.