Gearshift system, basic function

Overview

This document contains information on:

 General

 Function requirements

 Function

General

Combustion engines provide usable torque only in a limited rpm range. Therefore, the gear ratio is adapted to suit the desired vehicle speed using the gear selection. Gear selection is performed electrically or electrohydraulically by means of the fully integrated transmission control electrohydraulic controller unit and the dual-clutch transmission control unit. The following gear selection options are available to the driver:

 DIRECT SELECT lever

 Steering wheel gearshift buttons (manual intervention)

 Automatic transmission transmission mode button

Function requirements

 Engine in operation

 Clutch of sub-transmission disengaged

Function

An actuator moves the shift fork of the respective sub-transmission along the fork bar. Linear movement of the shift fork moves the sliding sleeve connected to the shift fork, axially along the output shaft. The axial movement of the sliding sleeve initiates synchronization between the output shaft and the idler gear of the selected gear range. After synchronization, the sliding sleeve is pushed by the shift fork onto the interlock teeth of the idler gear. Via the synchronizer body, a positive connection is then generated between the idler gear and the output shaft.

 The actuators of the corresponding shift forks can take the form of an actuator motor or regulation valve. In the case of the version with actuator motors, the gearshift linkages are actuated via selector drums.