Perfected over decades of operation manual transmission is nearly certain advantages: simple, reliable, inexpensive to manufacture and maintain, provides good dynamics and low fuel consumption. Only one drawback annoys some drivers: manual control and manipulation of the pedals. In the crush of the city is, in fact, gives little pleasure.Marketers and designers asked a thought: Is it possible to combine the advantages of the “mechanics” and “automatic” in one box? The idea came to life with the advent of the electronic “brains” that can make a decision about the need to shift and control actuators.Simple “robot” – this is a common manual supplemented by a control unit and two drives. One drive is turned off and the clutch, the second controls the gear shift mechanism. Drives are either electric or hydraulic. Practice has shown that the box with hydraulic drive is preferred. All boxes have robotic manual mode shifting.

I must say that the “first attempt” has turned out lumpy. According to the results of numerous test drives, reviews of the owners of the simple “robot” was felt as a “raw” design, the management of which should be used to it. For example, to avoid jerks, it is recommended to switch the momentum a little throttle. Unpredictable this box may behave in difficult road conditions – on a steep incline or a slipping wheel. Movement around the city often turns into torture: a sharp start, jerking keep in constant tension. When city driving possible overheating of the clutch. The switching time can be up to 2 seconds. Such delays are related to the fact that the robots come to the production cars from the sport. A racing sequential (sequential) gear shift is ideal. In a conventional car it is sometimes necessary to switch through several stages. And then the robot begins to “think.” In general, to comfort “machine” design obviously does not hold.What about the advantages? They also have: simplicity and low cost (at least, for the manufacturer), economy, a rigid connection between the engine and the drive wheels, which allows engine braking or put “gas” car from skidding.
A box with two clutches

A further embodiment of the idea to combine in one unit the dignity of the “mechanics” and “automatic machine” became a box with two clutches. A pioneer in its implementation was the “Volkswagen”. In its execution it was called DSG. Such a box is composed of two primary shafts (wherein one hollow shaft and the other is inside the first), the two secondary shafts and two clutches. A “set” is intended to include the odd gears, the second – for the even. As switches?  Two adjacent transmission constantly included. For example, when moving from place includes first and second gear, but only one clutch is closed. When electronics decides that it is time to switch, “odd” clutch open and the “even” closes. After opening the “odd” set immediately include third gear. Since the inclusion of transmission takes place in advance, then a box called preselektivnoy. If a change of gear takes place sequentially, switching occurs within milliseconds. Otherwise (if necessary switch in the next, and immediately after a few steps) process can take up to one second. This is the case with “simple” robots, is a consequence of “racing” past.
The first was a six-speed DSG is. It is not aggregated with “weak” the motors as part of the power is constantly selected to drive the hydraulic pump. In addition, the efficiency reduces “wet” clutches, use as a clutch. Therefore, the “Volkswagen” has developed a seven-speed DSG with dry clutch and electric pump working constantly, but only when the pressure falls below the minimum. Seven-speed DSG are installed, usually on low cost cars.Boxes with two clutches of consumer qualities are a good compromise. They are economical machines; comfortable “simple” robot; can transmit more torque than the variable speed; provide a rigid connection between the engine and wheels, as mechanics. But at the same flow rate higher than that of the robot, comfort worse than that of the machine and the variator price substantially higher mechanics.

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