Almost everyone probably remembers the first independent attempt to pull away in a car with manual transmission. The left leg is angry with his right hand, she responds in kind. Motor stalls or abruptly throws you forward. And start up the hill quite fun. It is also fun to learn to ride on the oh-oh, very low speed: just wanted to pin down the clutch pedal is not paying attention to the dissatisfaction with the instructor and the smell of burn pads. And how is it charged up after all this is the opening: the pedals in the car may be not three but only two ... and the engine will not stall, no matter how inept or was your right leg.
How is the engine that spins constantly, connected to the wheels, remaining motionless, if the car stood at traffic lights? Why did he not deaf and did not undercooked? An automatic transmission - the device is rather complicated, but simple experiment will help clarify some things.
The problem of state-scientist: you need to pass the time on the rotating shaft at a fixed, not mechanically joining them!
The solution - in the photo. We put one against the other two fans: one depicts the engine crankshaft, the second - a shaft of the gearbox. The first plugged in: the blades whirled and created the pressure of air - that the impeller and the second was set in motion! And her energy is already possible to use it. If you slow down the blade (Take care of your fingers!) Of the slave, the master of this fan does not respond and will continue to rotate. That's all.
This automatic transmission is much more complicated, but the moment the engine is transferred to it the same way. Paddle-wheel on the crankshaft acts as a pump that creates a stream of special oils, blades driven "fan" as the turbine work. Oil chased around by returning part of the energy back to the pump. The whole construction took shape donut - it is set between the engine and the actual transmission with planetary gears series. Transfers energy to the flow of hydraulic fluid that is discarded from the blades of the turbine blades to the pump.
In practice, perfected a bagel (and complicated!) So that it is from the coupling (this was, for example, in winter) into a torque converter. Here, between the pump and turbine wheels is yet another - the so-called reactor, associated with the impeller through the overrunning clutch. In a large difference in speed pump and turbine reactor blocks - then come to the impeller more fluid, the torque increases under heavy load about three times.
Why do I need an ordinary box with its gears? If a bagel is able to vary the amount of torque depending on the load on the driving wheels, the "what else?" Unfortunately, very limited ability of a donut, so to replace a range of five to six gears, he could not. In addition, because the need to organize a reverse mode, "'s land", "parking".
For a long time considered the lack of torque converter slippage of the driven impeller and leading each other, leading to increased fuel consumption, but today have learned to automatically lock them together in the regime of uniform motion, so that the machine with a gearbox spend nearly as much fuel as a mechanic.