autopressnews.com car magazine, homepage banner

New Fiat 500 minicar: Gearboxes

2008 Fiat 500, dashboard view.

Gearbox: mechanical or of the sequential robotised type.

A range of gearboxes has been developed to match the new Fiat 500 engine range: one is a mechanical unit (with 5 speeds for the 1.2 and 1.3, and 6 speeds for the 1.4), the other is of the sequential robotised type, and will be available after the launch on petrol-engined versions.

The Dualogic gearbox automates the clutch and gear lever controls by means of an electrohydraulic servo, but maintains all the advantages of a dry clutch and a mechanical gearbox (weight, sturdiness and reliability, low energy consumption).

There are two operating modes: semiautomatic and automatic.

The semiautomatic mode adopts advanced control strategies to guarantee the best performance. Gears are engaged using the lever on the facia. Because there is no clutch pedal, the device is controlled simply by moving the lever: forward to change up (towards the ‘+’ symbol), back to change down (towards the ‘-‘ symbol). A simple push is sufficient to ensure the transmission makes a fast, accurate gear change.

Most of the electric signals reach the control unit by CAN (Controller Area Network) and can be grouped in two large subgroups. In one, the data from the gearbox area, which make it possible to identify the engagement position, the selection, the clutch, and the operating pressure of the hydraulic kit, as well as the rotating speed of the clutch. In the other, all the signals coming in from the control lever on the tunnel or the levers on the steering wheel (which are optional), that let the driver decide when he wants to change gear, and those from the other systems on the Fiat 500 (for example, the engine and braking system), which help to define the gear change precisely and repeatably. For example, coordination with the engine control unit makes it possible to change up without having to release the accelerator pedal or to automatically increase engine speed when changing down (double de-clutch).

Using these two groups of signals, the Dualogic gearbox can manage gear changes in a comfortable or sporty way, in the manual or automatic mode, interpreting the driver’s needs by analysing the pedal position and the engine speed.

Once the engine on the Fiat 500 is started, any pressure on the brake pedal confirms that the driver is at the wheel, and enables first or reverse to be engaged (on a slippery surface it is also possible to set off in second). And to guarantee safety and prevent incorrect gear engagement, the system engages neutral automatically when a door is open with the engine running. The Dualogic device also prevents errors that might damage the engine or gearbox, by notifying the driver of emergency situations or incorrect manoeuvres with warning lights and beeps.

The automatic mode of the Dualogic system offers two settings on the 1.2 version: Normal and Economy. The Normal setting provides outstanding driving comfort, with gear changes in all conditions. The Economy setting, on the other hand, is used to reduce fuel consumption. On the 1.4 16v engine, the two settings are Normal and Sport (with the Sport button on the facia). The Sport setting activates a faster gear change logic that minimises the torque gap and thus makes the car more ‘fun to drive’ for the driver.

In automatic mode, the system recognises the road gradient (by means of a software algorithm) and modifies the gear shift point to ensure the best possible compromise between the driver’s needs, ground conditions and vehicle situation (speed and engine rpm). Another feature peculiar to the Dualogic gearbox is its ability to measure the vehicle deceleration and adapt gear changes accordingly. For example, in semiautomatic mode, and particularly with a sporty driving style, the system changes down when the driver asks for a lower speed to take a corner with more gusto. In automatic mode, the system anticipates the change down so that the driver has the best speed to maintain the level of comfort or fuel economy..

Reproduction of any part of this site is prohibited for any kind of publications: see our copyrights page.