Shift elements

Brakes and clutches are described as shift elements that enable shifting and changing gears. The automatic transmission needs only five shift elements to change eight gears. The following shift elements are used:

• Two fixed multidisc brakes (brake A and B)
• Three rotating multidisc clutches (clutches C, D and E)

The multidisc clutches (C, D and E) transmit the drive torque to the planetary gear train. The multidisc brakes (A and B) support the torque against the gearbox housing.

Clutches and brakes are closed hydraulically. For this purpose, a piston is pressurized with oil to compress the disc sets. All shift elements, except multidisc brake B, are pressed back into their initial position by a disc spring as soon as the oil pressure drops. Multidisc brake B is opened hydraulically. The shift elements enable changing gears without traction interruption. For this reason, all gearshifts (from first to eighth gear and back) are performed as overlapping gear changes. During the shift process, the "transmitting" clutch remains actuated with a lower pressure value until the "receiving" clutch can transmit the torque.