Alfa Romeo MiTo

Operation overview

The TCT system for C633 has the following features:

• It improves the performance of manual mechanical transmission components.

• It saves the driver from having to operate the clutch pedal and the conventional gear lever.

• It improves driving safety by implementing a control that prevents driver errors and the incorrect operation of the drive system.

• It is a hydraulic gearbox and clutch power assistance system that offers all the advantages of a dry clutch and manual gearbox (weight, strength and reliability, low energy consumption).

• It is simple to use and makes driving less tiring, especially in towns.

• It provides comfortable gear shifts, comparable to those of an automatic gearbox, by using advanced assistance power logics.

• There is no clutch pedal in the passenger compartment and the gear shift lever is replaced by "P (Parking) R (Reverse) N (Neutral) D (Drive)” commands on a joystick located on the dashboard.

• Gear shifts may be suggested in automatic mode, using the lever (TIP) or the buttons (TAP).

• The gearbox may be automatically managed in "AUTO" mode.

There are two Alfa TCT transmission operating modes:

• SEMI-AUTOMATIC MODE (MANUAL): the driver manages gears shifts using the lever located on the tunnel.

• AUTOMATIC MODE (AUTO): the electronic system manages the decision to shift gears.

General diagram with the main components of the Alfa TCT transmission.

Fig. 3 – Application on Alfa Romeo Mito

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Fig. 4 – Future application on Alfa Romeo Giulietta

The power assistance system consists of an electrohydraulic unit (1) mounted directly on the gearbox casing, which manages the following movements by means of two actuators:

• gear selection and engagement movement,

• clutch opening/closing control.

The electrohydraulic unit is controlled by five solenoid valves (which receive the required hydraulic power from an electric pump and accumulator).

By identifying the driver's requests according to the position of the lever (3), an electronic control unit

TCU (2) autonomously manages gear shifts, by directly controlling clutches, gearbox and engine torque; while shifting, the engine control is interlocked to gearbox control.

The synergy between gearbox and engine considerably improves system performance and saves the driver from any need to synchronise clutch-accelerator movements while shifting. Gears may be shifted with the accelerator pressed.

The system inhibits incorrect gear shift requests and prevents the engine from stalling or over-revving.

In terms of driving assistance, the system also ensures immediate availability of first gear when the vehicle stops and the automatic down-shifting in the case of sudden deceleration.

The selected gear is shown on a display integrated in the instrument panel, along with indications of faults and critical vehicle or gearbox component driving conditions. Warnings and faults are indicated by messages and general or gearbox failure warning lights.

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