Automatic Transmission, How it works? 

You know those videos where someone explains something complicated, in a simple way, and suddenly you see how easy it is? This is not one of them.

Me: trying to understand Narrator: *Adds another clutchpack and planetary gear set* Me: Blue screen of death

These comments are awesome! I just finished a transmission class in college and didn't fully understand how an automatic transmission works, so I thought I would watch a video on it, and now I still dont understand.

*For anyone struggling to understand:* _First watch the video and try to understand where parts are and how they interact and come back to this comment if you have questions._ (I'll be referring to each part as P1, P2, P3, P4, and P5. C1 acts on P1, C2 acts on P2, C3 acts on P3, C4 acts on P4, and C5 acts on P5) P1 is the Hub and case P2 is the P4 planet carrier and clutch module P3 is the first set of gears (ring gear, planet gears, and sun gear) and the P4 planet carrier P4 is the second set of gears (ring gear, planet gears, and sun gear) and the P5 planet carrier P5 is the third set of gears (ring gear, planet gears, and sun gear) and the output shaft In this type of automatic transmission the clutch packs are always in contact with whatever they're meant to engage with they're just allowed to spin freely. This creates friction between any parts in contact with the clutch packs which is why manual transmission systems are generally more fuel efficient. When the clutch packs are engaged they are no longer able to spin freely to induce a lot more friction in turn stopping what they're engaged to. For example: The C1 clutch is connected to the hub (gear) on the end of the input shaft and the case on the intermediate shaft. When disengaged the C1 clutch will be able to spin freely without imparting much of any force on the intermediate shaft. When engaged the C1 clutch increases friction with the hub to essentially extend the hub to the case and apply force to the intermediate shaft. This lets the input shaft turn the intermediate shaft directly as long as the C1 clutch is engaged. *For the first, seconds, third, and fourth gear:* The C1 clutch pack engages to turn the intermediate shaft as explained above. The intermediate shaft is only connected to P4 and P5 sun gears so C1 only affects P4 and P5. *First gear:* First gear uses P1 and P5 C1 and C5 engage in first gear. C1 engages because the intermediate shaft is only turned when C1 is engaged. This means that the sun gear in P5 is only turned when C1 is engaged. A problem arises however, if we only engage C1 we'll also be turning the sun gear in P4 which can turn the P5 planet carrier/ring gear. To combat this C5 is also engaged. This "connects" the P5 ring gear to the transmission case. The transmission case is stationary so when C1 engages it stops the ring gear from being able to turn. So C1 engages to supply force to the P4 and P5 sun gear. C5 engages to stop the P4 sun gear from turning the P5 ring gear. *Second gear:* Second gear uses P1 and P4. C1 and C4 engage in second gear. C1 engages because the intermediate shaft is only turned when C1 is engaged. This means that the sun gears in P4 and P5 are turned only when C1 is engaged. When the P5 sun gear turns, it only turns the P5 planet gears. When the P4 sun gear turns, it turns the P4 planet gears however these are connected to the P5 planet carrier. This means that the P4 planet gears increase the speed the P5 ring gear. This leads to the planet gears turning more quickly than in first gear. This increases the output shaft turn speed. A problem arises when we don't engage C4. The P3 sun gear isn't connected to the intermediate shaft but instead connected to the input shaft. This means that the P3 sun gear turns at any point the engine is supplying force. The P3 planet gears turn the P4 planet carrier at the same rate as the input shaft, this would be 1:1 input:output which would require too much force from the engine. This would result in the engine stalling (Results in a jump from first gear to fourth gear) To combat this, the C4 clutch is engaged. The C4 clutch "connects" the P4 ring gear to the gear set case. This means that C4 stops P3 from supplying force to the output shaft. So C1 engages to supply force to the P4 and P5 sun gears. C4 engages to stop the P3 sun gear from turning the P4 planet carrier (prevents a jump to fourth gear). *Third gear:* Third gear uses P1 and P3. C1 and C3 engage in third gear. C1 engages to turn P4 and P5 sun gears. The P3 sun gear connects directly to the clutch module which is in turn connected to the input shaft. This means that the P3 sun gear is turning as long as the engine is supplying force. A problem arises when C3 isn't engaged. The P3 ring gear is only connected to C3 and the P3 ring gears. When the P3 sun gear turns while C3 isn't engaged it would turn the P4 planet carrier. This means that they will enter fourth gear resulting in engine strain/stalling. When C3 is engaged, the P3 ring gear remains stationary slowing the P4 ring gear. This means that the force supplied to the output shaft is decreased. So C1 engages to supply force to the P4 and P5 sun gears. C3 engages to reduce torque required from the engine (prevents a jump to fourth gear). *Fourth gear:* Fourth gear uses P1 and P2. C1 and C2 engage in fourth gear. C1 engages to turn the P4 and P5 sun gears. P2 is connected to the clutch module and the P1 planet carrier When C2 is engaged, P2 turns at the same rate as the input shaft. This results in the ring gear and sun gear of P5 turning at the same rate. This means that the input and output shaft turn at the same speed. If C2 is not engaged you would remain in fourth gear but it requires more force to turn the output shaft which is less efficient. This is because P3 is connected to the input shaft. So C1 engages to supply force to the P5 sun gear. C2 engages to supply direct force to the P5 ring gear. *Fifth gear:* Fifth gear uses C2 and C3. C2 engages to turn the P4 planet carrier. C3 engages to stop the P3 ring gear. With C1 disengaged the intermediate shaft can rotate independently of the input shaft. When C3 is engaged it prevents entering fourth gear and supplies the P4 ring gear with force. This results in a greater turn rate at the output shaft. So C2 engages to supply force to the P4 planet carrier. C3 engages to supply force to the P4 planet carrier and prevent fourth gear. *Sixth gear:* Sixth gear uses C2 and C4. C2 engages to turn the P4 planet carrier C4 engages to stop the P4 ring gear. With C1 disengaged the intermediate shaft can rotate independently of the input shaft. When C4 is engaged it prevents entering fourth gear and supplies the P4 planet carrier with force. This results in a greater turn rate at the output shaft than fifth gear because it requires more torque to move the input shaft. So C2 engages to supply force to the P4 planet carrier. C4 engages to stop the P4 ring gear and prevent fourth gear. *Reverse gear:* Reverse gear uses C3 and C5. Force is supplied to the intermediate shaft through P3. C3 is used to stop the P3 ring gear to prevent counter rotation from P4/friction. This allows the P3 planet gears to revolve around the P3 sun gear. This results in the P4 ring gear turning in the same direction of the input shaft. The P4 ring gear will cause the P4 planet gears to rotate in the same direction. The P4 sun gear will rotate in the opposite direction of the planet gears. This results in the intermediate shaft having opposite rotation to the input shaft. C5 is used to stop the P4 ring gear to prevent counter rotation from the output shaft/friction. This allows the P5 planet gears to revolve around the P5 sun gear. The P5 sun gear rotates in the opposite way to the input shaft. The P5 planet gears revolve around the P5 sun gear in the same direction it rotates. This supplies a force to the output shaft that is opposite the force supplied to the input shaft. So C3 allows P3 to rotate the P3 planet carrier. C5 allows the P5 planet gears to revolve around the P5 sun gear. If you have any questions feel free to ask in the replies!

I understood this, right up to when I started the video

“This is the simplest form of an automatic transmission” *nervous laughter*

Some kid in my freshman engineering class made a full working miniature Lego car. Working electric engine, complete with working Lego power windows, and a full complete lego automatic transmission. Took him about 2 and a half years to complete. The guy was absolutely insane.

Would you now explain something simple, like the quantum phase shifting of subatomic particles?

I was a physics major in college and there was definitely some stuff where I just accepted it and said well the numbers work out. This is one of those times.

I've watched and rewatched this, the only thing that makes sense is why transmissions are so damn expensive

Well, you did an okay job explaining the "transmission" part. What about the "automatic" part?

Going to have to watch this a few more times. The people who figured out how to make transmissions have a lot to be proud of.

you know i think i’ll just let my car do its thing

After this I went and read some rocketscience to relax

Thank God for engineers... as weird as they are, I'm extremely grateful for the knowledge snd skill they possess to make things like this possible. This stuff is mind boggling.

"But here is the tricky part..." Melted brain: oh it's tricky now, isn't it?

When they say "it's not Rocket science", they really mean to say "it's not an automatic Transmission".

Learning difficulty: 1) Light speed 2) planetary colonisation 3) galactic travel and using sub dimension engines for first time dimensional travel 4) space time reversal using gravity in a black whole 5) simplest form of automatic transmission

I didn't have the idea that it happens all after simply pressing my accelerator. One of the brilliant inventions of engineering.

Whenever I become happy thinking about a planetary gear set and how it operates, another planetary gear set is added to make me unhappy about this endless process.

normally i feel smarter after watching a video... not this time.

Well now I love manual transmissions even more. This left me with more questions than answers.😂

Me 2019: ''I will NOT drive an automatic UNTIL I understand this video'' Me 2030: (Still driving a manual)

Manual Transmission = harder to operate, easier to understand Automatic Transmission = easier to operate, can barely understand.

I always wondered why it took a second to engage from N to D. I'm never going to complain ever again.

Thank you for helping me to understand transmissions less than I ever imagined possible.

"If you want to achieve six gear, just remove C1 and add C4" oh so basically im gonna turn my car into a bomb

How on earth did ANYONE come up with this contraption? Cannot even in my wildest fantasies conceive of this. Goddamnit!

1st gear: okay, got it, understandable 2nd gear: what kind of hell is this...

Both of my ex-brothers in law have their own automatic xmission repair shops, and neither one finished 11th grade. As someone else commented, their brains must work differently than most of us.

I understand the basic concept. You apply certain clutch packs to engage certain planetary gear sets to use a certain "gear". I still couldn't explain it in detail, like I could a manual transmission, but I think I get it.

This gear design in Machine Design II course, it was the toughest course in mechanical engineering, the longest formulas we had to play with. Prof gave us open book exams and good luck passing it.

Me: An animation can prove helpful to understand this *7.35 mins later* Still cannot understand what tf was actually rotating and what was stationary.

After watching this a few times over a few months, and understanding how clutches work. This makes a lot more sense.

For anyone wanting to understand this the easy way just understand that '"C" stands for "clutch pack" and applying different combinations of clutch packs generates different gears. 1st gear: C1 + C5 (clutch pack 1 + clutch pack 5) 2nd gear C1 + C4 4th gear: C1 + C2 6th gear: C2 + C4 3rd gear: C1 + C3 5th gear: C2 + C3 Reverse: C2 + C3 + C5 Also: C1 connects input shaft to intermediate shaft C2 connects the hollow shaft to the rotating clutch module C3 connects the ring gear of the 3rd planetary gear set to the case C4 connects the ring gear of the 2nd planetary gear set to the case C5 connects the ring gear of the 1st planetary gear set to the case

God bless engineers, if it was up to me you all would still be riding horses

brain was like: 1:00 uhuh. ofc 2:00 oh, i see 3:00 whoa.. science. 4:00 wait wut? rewatch 4:00 oh, i get it. 5:00 ... rewatch 5:00 ... rerewatch 5:00 oh, look. Funny cat video in the recommended.

Thank you. Incredibly complex machines to do something most of us take for granted every day.

Too bad this type of transmission wasn't available in the 60's... those explanation videos are the best...

I wonder how many people are getting lost after the first 3 mins...

No matter how many times I watch a video about automatic transmissions and planetary gearsets, I always come away scratching my head and realize the people who come up with these are on a different level.

OK wow. The transmission engineering is INSANE! That is absolutely amazing technology! I can’t believe I finally understood how this thing works!!

traditional transmission lesson : "I got it" automatic transmission lesson : "um... excuse me, could you repeat it again?"

after 2nd gear, my brain crash

Now I need an automatic transmission for my brain.

So this is the “simplest form of an automatic transmission . “ I thought I could follow this. I’m humbled once again.

After 68 times of watching; I think i finally understand 2nd gear.

If i apply c4 the homeland security will be calling me in the next two hours.

Q : How complicated do you want your transmission? A : Yes.

Manual transmission videos are easy to understand, everytime I watch an automatic transmission video I fall asleep for 4 hours.

They was the best explanation I've ever seen in my life

Watching a video how a jet engine works is easier to understand than this.

3:55 "but here's the tricky part"

All of this in my $500 piece of crap Chrysler, Engineers are truly underrated, their work is not valued at the level of ingenuity it takes to develop the technology we use for comfort.

omg, after 30 mins and 2 other videos I finally understand how this works, and holy there are so many clutch packs

Honestly, I've never met an automatic transmission mechanic that wasn't a meth addict. And, I've never had any problems with the work that they have done.

“This is the simplest form of automatic transmission” well that’s reassuring

To understand how the CLUTCH plates are engaged, please watch our video on Limited Slip Differential. It is explained in a detailed way there.

First time watching. It's like magic. Many areas don't use them because they don't know how to service them.

I pressed pause and left this video for the recommended video "how the universe works" because that I can understand.

Thanks for sharing. I'd love to work in the Transmission industry somewhere. I've successfully rebuilt an AX4S Ford Transmission in my 2000 Windstar and still driving it today. I do realize that that is a long ways from being a fully trained knowledgeable Transmission guy but its a start. I built my own clutch press as well and cut down push pins in a lathe to press in bushings.

So, combinations are: gear -> clutches (gear ratio) 1 -> C1, C5 (3.10) 2 -> C1, C4 (1.81) 3 -> C1, C3 (1.41) 4 -> C1, C2 (1.00) 5 -> C2, C3 (0.71) 6 -> C2, C4 (0.61) R -> C3, C5 (-3.10?)

It's been 2 decades I'm trying to understand this thing. Still can't get much out of this videos

my brain couldnt even engage 1st gear.

In about 1979 I rebuilt a Holley 4 bbl. Carburetor for my Plymouth's 383 Magnum. My dog watched me rebuild that Carburetor and I swear he had the same look on his face as I have while watching this video! Who the hell dreamed up the Automatic Transmission? My son went to 6 years of University and has an advanced Mechanical Engineering degree and even he has trouble explaining how these Transmissions really work. They actually work really well but I'll be darned how the first guy to build one got it done...

1st gear brain stat:100fps 2nd gear brain stat: 12fps 3rd gear brain stat: reboot

I rather think it's a good educational video. Watched enough times and play with a few transmissions from the junk yard and I think I'll have a better understanding. So thank you to the creator of this video and keep up the good work.

This video has confirmed that I am stupid.

My brain stalled…

I think of myself as a smart guy, ... But I started freaking out when I got lost 2 minutes into the video, but after reading the comments I regained some of my confidence back.

Tl;dw: spinning stuff inside of spinning things.

"If we apply C4 as well, the whole car explodes."

I was feeling so demotivated that I couldn't understand the video but hey... I'm not alone 🤣

When the sun and planet gear come in play, I'm totally lost in the universe.

I feel like this video gives new meaning to the "plot thickens" meme.

I watch this just to relive the old days😁. All my vehicles are now EVs, but it took me back to school shop!

Could you do a 'Dem Bones' version to make it a bit easier ? :)

It's no use. It's still a box of magic to me.

Human enginuity never ceases to amaze me.

Oh my gosh! This video was very informative. I learned a lot about how brake fluid lubricates the master cylinder in the engine block, and how 3rd party combustion engines work with electrical hybrid engines, such as the one in Ford Camry's.

brain.exe has stopped responding...

Note : It will take 2 more weeks to release the 2D Animation video.

After months of rewatching this video I finally understood how it works

Clear as mud! I'm sorry but that video left me more confused than I was beforehand.

lost me at planetary gearset

To think somebody thought of this and invented it, but yet I can't even understand or grasp a piece of it, just makes you feel very dumb and amazed at the same time.

after rewatch this video for 3 times, and other videos, I finally understand it. Thanks, you're doing a great job

Watched it 2D first and then watched this.. Both videos are very well explained. Thank you..:)

I watched this last night and didn't understand...but I still had the picture of the arrangements in my head. So I slept off and I dreamt about it😂..... watched it again this morning and it totally made sense now. You just need to apply a combination of clutches to combine certain gear ratios to create a varying output. It's as simple as that.

I have a new found respect for the Allison 1000 in my old truck!!!

I’m a qualified motor mechanic/engineer...but even I scratch my head when it comes to understanding auto trans...in school it’s more engine and electrics that is touched on trans is taught as a different subject because of the complex nature ...as with anything tho..if you have a strong interest that’s what will make it stay inside that ol grey matter.. I was also going to add that when I first looked at this vid..I tryed to see it as it’s all about locking and unlocking different parts of the unit to get different gears working for different driving situations..that my way in for getting that opening understanding in a nutshell ...

Watching this now I realize why mechanics charge so much to fix a Transmission.It requires a lot of work and time.Salute to Mechanics!!!

Teacher: the test is not that confusing *THE TEST:*

I thought I would sneak in some comments before I made my own! I feel so much better now knowing that I'm not the only one that needs to watch this about 100🤔 PROBABLY 1000 times more just to get out of first gear🤷‍♂️

MY BRAIN IS COMPLETELY SMASHED WITH CONFUSION AND I HAVE RECENTLY GOT MASTERS IN AEROSPACE ENGINEERING. HAHA SOMETHING IS WORNG

I mean, it's hard to have the whole thing in your mind at once but you just have to think that each state of the gears is basically you choosing how many gears torque transfers you want to add, each set of planetary gears having two inputs - the ring and the planet gears connected to the previous rings or the original inputs (engine shaft, rotating clutch, intermediate shaft). Since the sun gear is much larger than the planet ones, applying torque to it while the ring is stationary will get you more on the planet gears, and applying torque on the planet gears will reduce the torque you get. If the ring is moving, however, the torque goes to both via 2 input methods! It's the same as a manual transmission, except that it is much more compact, as you can make gear combinations on the go instead of having one gear or a set of gears for each torque-speed combination, and it is also very smooth as the only place were disengagement occurs is on the clutches and it has a torque converter. In fact, you can sort of think that planetary gearsets are associated with automatic transmissions just because they are often placed together; A car may as well be automatic and have a conventional gearset (not that it does much sense, a lot of adaptation would be needed), and vice-versa.

as someone who works on his own vehicles.... I'm glad I have a 5spd manual!

Honestly on a base level, the concept of an automatic transmission was not that hard to learn; it just really starts to get complicated when you introduce more gear combinations. So it makes sense that a 2 speed automatic transmission on my gas powered r/c car is (relatively) not complex compared to a 6-speed + reverse car transmission, I guess I also understand why my r/c car does not have a form of reverse gear while the electric r/c cars have them

Lost me at 5:50, but everything else actually made sense. I'll come back in a few years and see if I understand the whole video. It's been really helpful for me. The only thing I question now is how those clutch packs engage.

This guy's patreon should pay all 9.7 million people that watched this video.