Gear Actuation
When no gear is engaged the selector shaft is the neutral position in the shift gate between 5th and 6th gears. The piston in the selection angle cylinder (B) is pushed against the stop by a spring. The shift travel cylinder is in the central position in cylinder C (pressure is equal on both sides). With the selection of 1st gear, the piston in the selection angle cylinder (B) is charged with hydraulic fluid (pressure increasing mode). The SMG II control unit is informed by the position sensor (PS2) when the piston and consequently the main selector shaft (MSS) has reached the point in the shift gate between 1st and 2nd gears. The piston is the selection angle cylinder is placed in the pressure holding mode to maintain MSS position. Shift travel cylinder (C) is now activated via the control valves. One side of the piston in the cylinder is supplied with hydraulic fluid under pressure, the other side of the piston chamber is open to the expansion tank. The piston and with it the MSS is pushed in the appropriate position and a gear is engaged (either 1st or 2nd). A redirection of fluid on the shift travel cylinder piston will cause the other gear to be engaged. See Fig 1 .