Manual shifting from 1st to 2nd gear, function - GF26.60-P-3001A

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: Manual Shifting From 1st To 2nd Gear Function Diagram

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Hydraulic diagram (2nd gear engaged) 

Fig 2: Hydraulic Diagram (2nd Gear Engaged)

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Hydraulic function sequence during upshift 1 → 2 

When the driver's shift request is detected, the automated manual transmission control solenoid valve for gears R, 2, 4, 6 (Y92/2) is actuated by the automated manual transmission control unit (N15/6). The valve directs the system pressure (p) into pressure chamber II of the hydraulic cylinder (C). This moves the shift piston rod (C2) with shift piston (C4) in the direction of 2nd gear.

Pressure chamber I for the brake is pressureless, the brake pad (C1) is not actuated and the selector sleeve (C8) is freely movable. As the shift piston rod (C2) moves there is no positive force acting on the guide bolt (C7) in the shift gate guide (C6).

For the entire duration of the hydraulic sequence, the automated manual transmission brake solenoid valve (Y91) and the automated manual transmission control solenoid valve for gears 1, 3, 5 (Y92/1) are not energized. The solenoid valves are in their basic positions and there is a link to the oil reservoir outlet (0).