How do automatic transmissions work?

this is a model of an automatic transmission automatic transmissions are one of the least understood mechanisms almost all cars on the road are automatic so how do they work the first thing you'll notice is that there's an input and there's an output in this case the input is this yellow ring gear and yellow handle and the output is this orange ring gear right now there's nothing engaged they both spin at the exact same speed this is what's called direct drive where the input is exactly the same as the output this model of an automatic transmission contains two planetary gear sets a planetary gear set contains a ring gear planet gears and a sun gear if i rotate the sun gear you can see the planet gears rotating inside of the ring gear this automatic transmission model contains two planetary gear sets that share the same sun gear let's take it apart so we can see what's inside here you can see the two sets of planet gears orbiting around the same sun gear this blue part is called the planet carrier it holds the planet gears in place the important thing to note is that the sun gear is shared between the two planetary gear sets also the planet gears of the first planetary gear set are connected to the ring gear of the second planetary gear set now i'll show you how it actually works by demonstrating it these gears on the side are actually handles if i hold this blue gear it'll actually hold the blue planet carrier in place if i hold this red gear it'll keep the sun gear in place by changing which gear i hold in place it'll actually change the gear ratio of the gearbox before i demonstrate how it works it's important to know why we actually need automatic transmissions in our cars in the first place a car runs best at a certain rpm this rpm is a lot faster than we need when we're first starting out from a stop we have to ease up the speed of the output to do that we can start in first gear by holding the blue handle in place you can see the orange output ring is spinning much slower than the input now let's increase the output speed by switching to second gear we could do this by holding on to the red handle now the output ring gear is only slightly slower than the input ring gear we could switch to third gear or direct drive by releasing all of the handles we have now eased our way into our final speed some automatic transmissions have overdrive where the output spins faster than the input let's go back to second gear and then down to first gear first gear is slower but it gives us more torque i'll have these files for free on my website if you want to download them and 3d print them yourselves if you want to learn how to design things just like this and learn how to 3d print them check out my courses in the description below and that is how an automatic transmission works you

Channel: 3D Printer Academy

Views: 407,022

Keywords: automatic transmission, 3d printed, engineering, model, 3d prints, satisfying

Id: vLB_oSMHv7g

Length: 3min 33sec (213 seconds)

Published: Sat Jan 29 2022