Quote:
Originally Posted by Weeber
Hey guys I was just wondering why do the Auto transmissions have relatively smooth gear changes without any crunching?
Do they even have synchros?
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Is this a serious question?...are you trolling? In case you are serious I will try my best to explain...automatics don't have gears in the same way a manual does. They use something called planetary gear set and use clutch bands that grab each gear set separately depending on where the fluid gets directed too-these combined will be your "gears". Then there's also the fact that an automatic uses a torque converter which uses fluid to transmit power from the crankshaft to the input shaft-this acts like a clutch. So in simple terms when you start to accelerate from a stop the torque converter will start transferring power from the engine to the transmission which will then start with the 1st gear ratio via electronic servos and ecu, that will direct fluid to one side of the bands(think of this as wrapping your waist belt around a spinning round object but with one side fixed and you pulling on the other to stop the rotation of this "round object")thus grabbing that set of planetary gears which then turn the output shaft to the driveshaft, to the diff, and then finally to the wheels. When the transmission shifts it will shift the fluid to a different planetary set by applying fluid to that band and release the first, and will repeat the cylcle for each gear. Anyone chime in that knows better? I'm a little fuzzy on the details.