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Transmission |
Continuously variable transmission with
Steptronic
The automatic transmission offered for the MINI is an easy-to-operate continuously variable transmission
(CVT) that also contains Steptronic control. This means that the driver can choose between normal automatic mode, which makes driving in city traffic easier, and a more sporty driving mode with a six-gear semi-automatic transmission. Although the continuously variable transmission is still heavier than manual transmission, it is lighter than a conventional automatic transmission.
Continuously variable transmission
(CVT) is different than a conventional automatic transmission. Where conventional systems need a torque converter, the CVT uses an oil bath multi-disc coupling that is electronically controlled. The transmission itself uses a fixed-length steel drive belt to connect two double cone-shaped belt pulleys which transmit the drive output from the engine, essentially offering infinitely variable transmission ratios.
The Powertrain Controller continuously monitors the position of the belt pulleys and guarantees that the most suitable transmission is provided for current driving conditions. Because the trans-mission ratio can be varied endlessly and infinitely, this continuous adjustment is carried out smoothly without any "steps" in the transmission.
The CVT gearstick has positions for park, reverse, neutral and drive mode. The letters P, R, N and D indicates these settings, and an LED next to each letter shows where the selector position is at the time.
The CVT also has a Sports driving mode, engaged by moving the gear lever from position "D" leftwards to position "S". Sports mode contains a sporty tuning of the continuously variable operation. Within the CVT Sports mode, the driver can also select Steptronic for greater involvement in gear selection.
The transmission automatically changes from Sports mode to the Steptronic mode when the driver changes gear manually by moving the gear lever forwards or back. The shift status in Steptronic transmission is also shown on an LED display integrated into the speedometer. In Steptronic mode, the main differences from "D" or "S" mode are the fact that six fixed transmissions are provided. These "gears" are created by the fact that the CVT transmission is limited electronically to six pre-determined ratios. The Steptronic function offers a more agile driving feel, since the engine can run at up to 6,000 rpm.
Failsafe protective switching prevents errors that could damage the engine or transmission.
A steering wheel with Steptronic control is offered as an optional extra, with the switches on the front and rear of the steering wheel spokes. The switches on the front of the steering wheel change the gears up, and the switches on the rear change down.
Accelerating from standstill is particularly smooth with CVT and
Steptronic, since the electronically controlled coupling does not transmit the full power until an engine speed of 2,000 rpm is reached; instead, the power produced is restricted and transmitted evenly, resulting in rewardingly smooth acceleration. Both operating modes - CVT and Steptronic - have
"Kickdown", "Fast-off" and "Downhill" functions. The "Crawler" function, familiar to drivers of a conventional automatic transmission, is also provided electronically for the CVT and Steptronic systems.
Improved acceleration values compared with conventional automatic transmissions are a further advantage of CVT and Steptronic transmission.
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