H Toba answer this question what work these types of boxes have to remember the device normal manual gearbox. The basis of the classical “mechanics” is two of the shaft – primary (leading) and secondary (slave). At the primary shaft through the clutch mechanism of torque is transmitted from the engine. Since the secondary shaft is transformed when the driving wheels. And primary and the secondary pinion shafts planted in pairs which are in engagement. But the primary gear rigidly fixed, and the secondary – rotate freely. In the situation of “neutral” all of the secondary gears are scrolled on the shaft is free, ie the torque to the wheels did not come.
Before turning on the transfer of the driver presses a clutch disconnecting the primary shaft from the engine. Then lever gearshift through rods at the secondary shaft moving special devices – synchronizers. When closing the clutch synchronizer blocks rigidly to the shaft gear required secondary transmission. After switching clutch torque with a given factor begins transferred to the secondary shaft, and from him – on the main transmission and wheels. To reduce the overall length of the box main shaft are often divided into two, dividing driven gear between them.
Controls actuators electronic unit. At a command to switch the first actuator squeezes the clutch, the second moves synchronizers, including the necessary transfer. Then, first slowly lets out the clutch. Thus, the clutch pedal in the cabin is no longer needed – if the electronics team will do everything herself. In automatic mode, the team replaced the transfer comes from the computer, taking into account speed, engine speed, data ESP, ABS and other systems. And in the manual – an order to switch gives the driver using a selector or transmission podrulevyh petals.
The problem of “Robot” – the lack of feedback on the clutch. Man feels the time of closing disks and can switch speed quickly and smoothly. But electronics have to err: to avoid falls and maintain traction, “robot” for a long time breaks the flow of power from the engine to the wheels during the switch. We obtain uncomfortable dips on over clocking. The only way to achieve comfort when switching – to reduce their time. And this, alas, mean growth rates of the assembly.
A revolutionary solution has appeared in the early 80’s dual-clutch transmission with DCT (dual clutch transmission). Consider the example of her work on a 6-speed DSG box Concern Volkswagen. There are two boxes of the secondary shaft located on them, driven gear and synchronizers – like six “mechanics” of golf. The trick is that the primary shafts are also two: they are inserted into each other on the principle of dolls. Each of the shafts connected to the engine through a separate multiple-disc clutch. The outer drive shaft gear secured the second, fourth and sixth gears, the internal – the first, third, fifth and reverse. For example, the car starts to accelerate from their seats. Includes the first transmission (clutch locks the first driven gear transmission). Closes the first clutch, and torque through the inner primary shaft is transmitted to the wheels. Go! But with the inclusion of the first transmission clever electronics predicts subsequent inclusion of the second – and blocks its secondary gear. That is why these boxes are called preselektivnymi. Therefore, included two programs at once, but not seizure case – Leading second gear transmission is on the outer shaft coupling which is still open.
Today the box DCT is not only Volkswagen but also from companies BMW, Ford, Mitsubishi and FIAT. Preselektivnye boxes recognized even engineers Porsche, which are used in their cars only proven technology. Analysts predict that in future the most common transmissions would DCT and aviator. And the days of the third pedal, it seems to be numbered – soon it will disappear from even the most drayverskih sports car. Humanity chooses what is more convenient.