Engage gear range, function - GF27.60-P-3009AHW

TRANSMISSION 722.9 in MODEL 204.0 as of model year 2009/YoM 08 

TRANSMISSION 722.9 in MODEL 204.0 as of model year 2012/YoM 11 model refinement package 

TRANSMISSION 722.9 in MODEL 204.2 as of model year 2009/YoM 08 

TRANSMISSION 722.9 in MODEL 204.2 as of model year 2012/YoM 11 model refinement package 

TRANSMISSION 722.9 in MODEL 204.3 

TRANSMISSION 722.9 in MODEL 204.9 

Function requirements 

• Circuit 87 ON
• Circuit 61 ON

General 

Each gear change is triggered by the fully integrated transmission control (VGS). 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. The process is a smooth transition and the components affected are actuated directly. This makes it possible to downshift, even through several gears.

Function sequence 

Shifting "N" to "D" (1st gear) 

In the "N" selector lever position of the electronic selector lever module control unit (N15/5) the multidisk brake B3 and multidisk clutch K3 are engaged. By shifting from selector lever position "N" into selector lever position "D" on the electronic selector lever module control unit the feed to the multidisk brake B2 is enabled by the selector valve. The fully integrated transmission control unit (Y3/8n4) actuates the multidisk brake control solenoid valve B2 (Y3/8y6) and the 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 multidisk brake B2 is full. The multidisk brake control solenoid valve B2 actuates the regulating valve B2 and brake pressure regulation which converts the adjacent working pressure into shift pressure and passes it on to the multidisk brake B2

In the fully integrated transmission control unit, the required slip (specified slip) is stored for the respective gear. Depending on the specified slip, the multibrake disk control for the control solenoid valve B2 adjusts the control pressure at the regulating valve B2 and brake pressure controller.

The pressure in multidisk brake B2 is changed until the specified slip stored in the fully integrated transmission control unit is reached.

The shift pressure produced by the regulating valve B2 and BR depends on the geometry of the regulating valve B2 and BR.

No power in gear range "D" for model 204 in combination with engine 642 (as of 1.9.2008), with engine 651 (as of 1.4.2009) and with engine 276 (as of 1.3.2011) 

Function requirements 

• After engaging selector lever position "D" the vehicle speed v = approx. 15 km/h must be exceeded once
• The function sequence of "no power" in gear range "D" is activated when stopping the vehicle in selector lever position "D" if the following conditions are met:
  • Transmission oil temperature in range of 10 °C to 110 °C
  • Coolant temperature in range of 0 °C to 120 °C
  • Accelerator pedal not applied
  • Engine speed in range of 570 rpm 1000 rpm
  • Braking torque is at least 250 Nm and brake light switch (S9/1) operated.
  • Transmission-internal uphill slope calculation value < 18%
  • Transmission mode "E" or "S" selected
  • 1st gear engaged by fully integrated transmission control and no off-road gear or off-road program button (N72/1s25) is not active, (model 204.9)
  • VGS operating without faults

Function sequence 

The fully integrated transmission control prevents the current at the multidisk brake control solenoid valve B2 in such a way that the shift pressure is reduced to the backpressure spring level via the regulating valve B2 and brake pressure regulation and the multidisk brake B2 is converted into a controlled slip. This leads to a reduction in transmission output torque when the vehicle is stationary and to a reduction in fuel consumption.

The "no power" function sequence in gear range "D" is deactivated when at least one of the following conditions is met:

• Vehicle speed v > 0 km/h
• Transmission oil temperature t > 110 °C
• Coolant temperature t > 120 °C
• Accelerator pedal applied
• Engine speed n < 570 rpm or n > 1000 rpm
• Transmission-internal uphill slope calculation value > 25 %
• Braking torque < 250 Nm or brake light switch not operated
• A touch shift has been detected or the selector lever has been shifted out of selector lever position "D" into "N" "R", or "P"
• A VGS system fault was detected

Overview of system components for automatic transmission (AT)

GF27.10-P-9992AHW