Manual shifting from 2nd into 3rd gear, function - GF26.60-P-3002A

TRANSMISSION 716.6 in MODEL 203, 230 with CODE (424) Sequentronic automated manual transmission (SEQ) up to Model Year 08/modification year 07 

TRANSMISSION 716.6 in MODEL 208, 209, 211 with CODE (424) Sequentronic automated manual transmission (SEQ) 

Illustration of the principle 

Fig 1: Identifying Manual Shifting From 2nd Into 3rd Gear Function

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Hydraulic diagram (3rd gear engaged) 

Fig 2: 3rd Gear Engaged - Hydraulic Diagram

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Hydraulic function sequence during upshift 2 → 3 

When the driver's shift request is detected, the automated manual transmission brake solenoid valve (Y91) is actuated. This solenoid valve directs the system pressure (p) into pressure chamber I. This causes the brake piston (C3) to press the brake pad (C1) against the selector sleeve (C8).

Now the automated manual transmission control solenoid valve for gears 1, 3, 5 (Y92/1) is actuated. The valve directs the system pressure (p) into pressure chamber III of the hydraulic cylinder (C). This moves the shift piston rod (C2) in the direction of 3rd gear.

As the shift piston rod (C2) moves the shift gate guide (C6) exerts a positive force on the guide bolt (C7). The shift piston rod (C2) is twisted by one shift gate and 3rd gear is engaged.

For the entire duration of the hydraulic sequence, the automated manual transmission control solenoid valve for gears R, 2, 4, 6 (Y92/2) is not energized. This solenoid valve is in its basic position and there is a link to the oil reservoir outlet (0).