How Torque Converters Work - Automatic Transmissions

[@Gaaaah]

He's certainly come a long way since this video. I still find it so simply explained, no more no less. If he chooses to do this again, I'd love his take on Koenigsegg's torque converter and the engineering involved, and what has largely changed in torque converters over the past 50 years.

[@laser4398]

An OK explanation, but your style has improved and so I think maybe you should do this one again.

[@Wargasmiccaa]

I think everything from 2011 and back would benefit from being reuploaded in his new format, he speaks a lot better now and explains everything more clearly.

[@justanotherdrunk]

damn only 10 years after 9/11

[@jimbrown7363]

I'm working on a front wheel drive when I spin the front tires should the torque converter spin or dose it just spin under speed

[@misterchow]

Hello and welcome!

[@zohair307]

I agree. Especially if you could explain this using an actual dissected automatic transmission

[@EngineeringExplained]

Yes, they rotate in the same direction. Basically you're looking from the middle in the pictures. Imagine the pump as your left hand, and the turbine as your right. Put them together, then open them like a book - this is what the drawing shows.

[@maddpepe313]

Taking an automatic transmission class and I have been looking at this in a completely complicated manner. You helped me out in a whole 6 minutes! You're the GOAT

[@danielm34l]

You should really consider doing this video again!! Now you have a way much better explaning skill and video quality

[@sohojoe]

This is the 4th Torque converter explanation video I saw. None other really explained the role of the stator as well as you did. Congratulations! keep up the good work!

[@donmiles5080]

I've listened to three different videos explaining torque converters and this one is the most clearly explained.

[@KrazerRacer]

wow, i cannot believe auto transmission uses a liquid to keep the engine engaged with the transmission. this is why i LOVE engineering :D

[@EngineeringExplained]

Very cool stuff!

[@alanwelch8545]

Great explanation. I've worked with engines and transmissions (as a shade tree mechanic/engineer) but never looked in detail of the torque converter fluid flow pattern for years. The efficiency disadvantage (you mention) of the old school torque converter is partially why some savvy consumers prefer the later generation lock-up torque converters with aggressive engagement strategies (say above 1500 rpm). As well, a good lock-up torque converter gives that feeling that you are directly connected to the wheels ( most of the time) rather than the horrible "slush box" feel of the early pre-1990 designs. Nowadays, I can't think of a torque converter without lock-up but maybe there are some in special applications. Having said that, I still prefer a manual transmission overall for feel. Next choice is a good CVT as in a Subaru Impreza (some people will disagree). Thanks again for all your videos. You do a great job explaining engineering concepts to people with all types of backgrounds (non-technical and technical).

[@chinchoy2108]

Dude I swear you are the best. I was looking at this in other places and in 25 seconds you did a better job explaining this component. Thank you.

[@James_Haskin]

I just replaced my clutch a month ago. Just now I was talking to family (christmas dinner) and my uncle brought up torque converters. I had no clue how an automatic transmission worked. Thanks the info :D

[@cayman1021]

I have seen some beautiful CGI-made videos explaining the torque converter, but none of them can make me realize its operation. Your drawing is much easier to understand. Jeeeeze.

[@doganguler1]

I watched at least 10 different videos to understand torque converters and this video now is more clear to me thanks.

[@jeffmc9154]

It's pretty cool to watch a clip from the early days of this channel and see how far Jason has come 10-plus years later. Although his presentation is sharper now, and a remake of this video could improve on the original, I hope that if he revisits this topic, he will keep this older content posted as historical record of his beginnings half a billion views ago. Thanks for all the great work Jason!

[@EngineeringExplained]

@andrewmylyf No, all of the liquid motion is from the pump which is a series of stationary fans mounted to a casing which rotates with the flywheel. Hope this makes sense.

[@EngineeringExplained]

@Monstar001 Actually flexplates (as far as I know) are just the term for flywheels for automatic cars. The difference is they're typically thinner since the torque converter also has mass which is essentially carrying the same responsibility of a flywheel. The purpose of the flywheel is to even out the torque. Without it, the power sent to the wheels would be pulsating, instead the inertia of the flywheel keeps the power to the wheels smooth.

[@EngineeringExplained]

Modern maybe the problematic key word there. Your background in TC's is sure to be greater than my knowledge which can be fully understood in 4 minutes and 40 seconds. Thanks for sharing!

[@EngineeringExplained]

They're both always engaged. But the fluid coupling means they can rotate at different speeds.

[@FarmYardGaming]

Committing to truly learning more about cars with this channel was one of the best choices I've made, everything is explained in great detail but not to the point of frying my brain

[@malemoupi9671]

Hie hey your explanation is superb sir,I have long struggled to understand how the transmission operates but just by watching this video the light has come in,not only on this video but your couple of videos I grasp them fast, thanx brother keep it up

[@andyjack89]

THANK YOU, this information is well thought out and easily digestible. I am studying for the ASVAB and do well on all subjects except for the mechanical knowledge section. I have a solid understanding of physics (thankfully) so it comes naturally to me but have never worked on a car or seen this stuff in person which makes reading a mechanical explanation about as hard as describing what a dog looks like to a blind person. Will watch and "thumbs up" most of your videos

[@EngineeringExplained]

It's honestly fine either way, whichever you choose. Some engines (manual trans) will shut off fuel supply if you leave it in gear while coasting downhill, which could save gas potentially.

[@EngineeringExplained]

@Dotchetter Well since the systems are connected some of it will drain. But if the engine's not running then the torque converter's not spinning, so the fluid on the bottom half could easily remain in. But it circulates with the rest of it so I guess it's no big deal.

[@EngineeringExplained]

Close, but the torque converter is attached to the crankshaft (indirectly) so if the engine stops so does the TC. However, if the transmission stops the TC still runs. I starter motor initially rotates the TC/flywheel to get the engine running. Check out my video "starting a car" for more information on that!

[@EngineeringExplained]

I haven't done the math or research, but I would say it makes a good difference. That said, you don't want something too viscous, as it will tend to not move as much as a lower viscosity liquid. You want the liquid to be able to flow throughout the system so that it is capable of transferring the torque.

[@EngineeringExplained]

An automatic transmission which you manually select which gear to be in, electronically. It can be done with different types of transmissions, for example a dual clutch or a regular planetary gear auto.

[@EngineeringExplained]

They're turning the same direction. Take two sheets of paper and lay them in front of you. One the left sheet, draw a circle turning clockwise. On the right sheet, draw a circle turning counterclockwise. Now take the two sheets of paper, and put the two sides (with circles) together. The two circles are now turning the same direction. :)

[@PauloAugustoTolentino]

Absolutely. I heard that's how you "test" an automatic car transmission - by applying both brakes and gas at the same time and see at what rpm it will stall. But now, after your brilliant and didactic explanation, I know what it really tests is if the torque converter is working properly. Also, I would like to know if the Limited Slip Differentials that work with fluids are good in transfering torque to the other wheel, that is, if they have anywhere near the same ratio as a Torsen type diff.

[@EngineeringExplained]

Yes, basically the same thing. There are some comments below regarding this.

[@vijayvishnu467]

very well explained.. (y) Could you also explain about the freewheeling and the lockup mechanisms please? would be massively helpful.

[@canttouchmymopar]

Great explanation you should do a video on benefits and downfalls to higher stall TC for racing or street driving and also how the stall is set higher. Great video man.

[@DonTruman]

You sure have improved in 10 years... Anyway, pretty amazing engineering. And to think modern automatic transmissions are as efficient or even more efficient than manuals, even with the added weight. Probably massively complex too, though.

[@metodraginii]

I couldnt quite get how exaclty the turbine gets disengaged? Otherwise really comprehensible video, man. Keep it up!

[@EngineeringExplained]

flywheel* flexplate* They serve relatively the same purpose, the flexplate is usually just smaller since the torque converter has a significant amount of mass.

[@EngineeringExplained]

I believe that they are connected, and the transmission fluid flows between both.

[@EngineeringExplained]

@JamesHaskin Glad I could help! Merry Christmas!

[@EngineeringExplained]

The majority, yes. Though it can be done without such as a dual clutch transmission or CVT. That said, most DCTs the operator selects the gear.

[@teri-lynnbadry9422]

doing my second year parts tech course you explained it way better than my instructor did

[@EngineeringExplained]

Transmission fluid, I think the goal is to maintain a relatively neutral viscosity with respect to RPM, but it may change some at different temperatures.

[@EngineeringExplained]

I guess the biggest thing to understand is liquids aren't compressible. They have to go somewhere, so when a force is pushing a liquid, the liquid will push as well. Basic principle of all hydraulics. Air is compressible, so if there was air in the torque converter it could just spin and nothing happen - liquid on the other hand is forced to move.

[@EngineeringExplained]

Correct. The friction of the brakes is greater than the force supplied by the torque converter, so it simply spins and the car does not move.

[@siddharthvakkaleri]

Came back here for a quick reference.. The nostalgia is strong with this one!

[@TheRealTanSeeker]

Wow, he's come a long way in 8 years! I bet he would laugh watching himself here now haha

[@EngineeringExplained]

It's just the perspective I'm looking at them from. Both are looking at them as if you were between the two. Imagine the two images as paper plates, and fold them into each other. Now the arrows are pointing the same direction.

[@EngineeringExplained]

@my2004Ze33 Thanks for subscribing! Didn't know about the Z's torque converter. Personally I think I'd have to go manual just to have the control. Plus the Z comes with the awesome synchro-rev match.

[@KurterinoVD]

This is probably not the best place for this sort of questions, you'd better try a make/model-specific forum for you car. My tip: check the fluid level (very important in a A/T, if it's lacking oil, it could just pump air and not move at all), if that doesn't help go see a mechanic. Thanks for the video, good and simple explanation, I've learned something.. :-)

[@EngineeringExplained]

Lightweight flywheel would definitely help. Just a matter of how much torque can be supplied through the rpm range, and how heavy all of the components involved are (overcoming inertia).

[@turboluvr5404]

A very interesting aspect of torque converters is that they also provide about a 2.3 to 1 torque increase when starting from a stop. The energy transfered in circulating the fluid from the pump to turbine to stator causes this. Without the stator, it is a 1 to 1 ratio and is called a fluid coupling. Research the old GM Powerglide torque converter. That was like a 5 to 1 ratio and had an extra stator and pump.

[@EngineeringExplained]

Glad to help, you're welcome!

[@tommygunn8888]

finally someone who can explain how it works. thanks

[@cameronryan1697]

The fluid flowing in the circular motion is called a vortex and the stator sets your stall speed and is what torque multiplies :)

[@EngineeringExplained]

I'm happy you're happy.

[@EngineeringExplained]

@Dotchetter Yes, modern torque converters lock up at higher speeds so now power is lost through the inefficient design of a torque converter. Don't see any reason why the fluid couldn't last a long time.

[@greg55666]

I love these videos. Sometimes, and I think this is an example, it would be good if you had actual parts you could show us. Those combined with your white board would be really helpful. Thank you!

[@EngineeringExplained]

Without a torque converter you wouldn't be able to change gears, or have the car in neutral. There has to be an intermediary between the engine and the transmission so both can rotate at separate speeds when they are not connected (in gear).

[@Franco.martinelli]

Great, thanks for answering, I discovered your channel just a few days ago and have already watched most of the videos, great stuff!

[@shyzlolo]

Great videos. I am just starting to learn about cars and engines and helps me a lot before I buy my first machine. My question is, how does an automatic Transmission works without Torque Converter? The Ford now has that feature for fuel efficiency and eager to know how does that work.

[@EngineeringExplained]

Thanks for watching!

[@EngineeringExplained]

Do all TC's have it? Perhaps I should make an additional video sometime.

[@my2004Ze33]

@EngineeringExplained I have the 7 speed automatic version with paddle shifters and it is a tick faster and geared a little tighter than the manual. The control is actually pretty good compared to a manual (my previous car was a 350Z MT) because of this torque convertor locking feature that Nissan claims.

[@EngineeringExplained]

Yes, indeed. I try my best.

[@xiaotheman]

loved your explanation, however i think flywheel can only be found on manual cars while auto cars have a much thinner light plate called flexplate that is directly connected to the torque convertor

[@EngineeringExplained]

Traditional auto's require a torque converter. DCT's, sequential gearboxes, and CVT's do not. I have videos on the three of these. :)

[@simonwright6163]

No need for any apostrophes there :)

[@kroshan70]

Thanks ,it helped me a lot while preparing for my seminar.

[@spelunkerd]

The OP is correct. Although the turbine IS physically on the engine side when you stand at the side of the car and look at it, it is splined directly to a driveshaft that goes through a hole in the body of the TQ. The engine turns the whole body of the TQ, which is fixed to the blades of the impeller, driving fluid frontward against the vanes of the turbine. As to why they did that, I don't know! It might have something to do with optimizing output from the stator....

[@EngineeringExplained]

The flywheel is attached to the engine, so it won't matter what type of transmission is used.

[@NoFear4XJs]

Thank you for keeping it simple, great explanation much appreciated !

[@EngineeringExplained]

@mickblock Correct you are!

[@JS847321]

In response to the questions about the one way clutch. Because the pump and the turbine are not mechanically connected to each other, the turbine will never reach the same speed as the pump. If they did, then the fluid would no longer flow around the converter. So when the engine revs are high, and the turbine will rotate no faster, the one way clutch engages, and mechanically joins the pump and the turbine. Because at this point the output is slower than the input, when the clutch engages...

[@EngineeringExplained]

Yes, you've got it right.

[@EngineeringExplained]

Definitely an interesting suggestion, I'll keep it in mind.

[@inox1ck]

Well explained operation of the TC, but just one thing to clarify for the audience. In a manual you can also be in a higher rpm than the transmission, can't you? The clutch unless is fully released will never transfer all the effective power (minus heat losses obviously ) from the engine whereas a torque converter can transfer all the power from the engine and there will also be minor heat loses perhaps but on negligible amounts. The more you press the clutch the less power is transferred. Not the case for a TC. Well the TC has in fact a clutch. I'm not sure but I suppose it looks up quickly not like in a manual where you have to release the clutch slowly. All this is when starting from standstill otherwise the manual will also operate quick enough (depends on the driver :) ) and almost all power will be transferred. There is one more important thing. The stator can rotate in the direction of the pump. Once the fluid speed gets high, the forward flow will make the stator move with the pump and there will be no more torque multiplication. The cycling motion through the middle stops as the centrifugal force pushes the oil outwards creating a back pressure for the impeller outer flow. The input shaft will now rotate at the same time with the output shaft. Thanks

[@JS847321]

and the two parts are mechanically connected together, they are forced to turn at the same speed. This means that when the clutch engages, the engine is forced to reduce speed. As the engine speed picks up again, then the output shaft will rotate faster. In an automatic car, this 'lock up' feels and sounds a little like an extra gear change.

[@AlexAlex-Alex]

Hehehe, this was a while ago compared to the videos you produce nowdays. :)

[@lievenaw]

Should say something about how it also works as a hydrolic clutch but otherwise.. great video!

[@EngineeringExplained]

Ehhh, I'd disagree. If your clutch is slipping (doesn't hook up, tires don't spin or you don't launch) then your transmitting less torque because the friction isn't as high as if your clutch wasn't slipping, so the amount of torque you can usefully transfer is less. Also, it wears your clutch. Flooring it in a auto won't really produce any negative effects.

[@EngineeringExplained]

It spins, attempting to apply torque to the transmission, which is locked because of your foot on the brake.

[@360quickshot]

I have a test to write on these tomorrow, thanks for the refresh!

[@EngineeringExplained]

Excellent, +1 for old school huh?

[@fightingfalconfan]

Does a good job of explaining the Torque converter if your interested in a nearly hour long video. Hope this helped you.

[@Magnusintro]

lets say the engine is sitting at its peak torque range when I release the clutch(serviceable clutch) as quickly as possible while still maintaining the engine revs at its peak torque rpm, this is effectively dumping stored KE by the rotating engine plus the fact its operating at peak torque to move the vehicle. In a Auto perpective the Stored KE is in the fluid pressure applied to the driven end of the converter which is held stationary by the brakes. The two methods produce similar results.

[@EngineeringExplained]

And they serve the same purpose, and for all practical reasons are the same thing.

[@michaelsizemore983]

Could you explain how/why the stator provides torque multiplication by changing directions of the fluid? I have never understood this.

[@dacmm]

The stator provides a stable point in the converter that the fluid can 'push against' to create torque. If the entire thing was spinning, the fluid inside would also just be spinning after a while, and barely any force would be transferred by it.

[@EngineeringExplained]

Glad to hear it, thanks!

[@EngineeringExplained]

They are referred to as flexplates on automatic cars, but the idea is exactly the same as a flywheel.

[@EngineeringExplained]

Yep, serve the same purpose.

[@EngineeringExplained]

Yeah

[@EngineeringExplained]

Correct, the turbine is not on the engine side. But you are incorrect on the "I messed it up" part. :)

[@EgreenSVT]

Yes, I can't think of a modern application that wouldn't have a clutch, whether it be a slip clutch or a lock up. Also may be interesting to add something about the damper aspect of a TC. I'm also an engineer and have a background in TC's.

[@EngineeringExplained]

I don't know what a "2500RPM TC" is. Is that it's RPM limit?

[@EngineeringExplained]

Yep.

[@fightingfalconfan]

Think of it like this, the fluid in the torque converter is constantly moving. When you step on the gas, the middle blade (forget what it's called at the moment) changes direction and forces the fluid to rapidly change direction causing it to move faster. It's just like in a jet engine. You have compressor blades that are at a certain angle that speeds up the air even faster. Well in some ways air and fluids are alike. Untill you get them to compress. Air will and fluid won't. ETCG...

[@EngineeringExplained]

Sounds right.

[@EngineeringExplained]

Well if you're in neutral it can rev up to whatever speed your engine goes to. So yes, you'd have in a sense a "more powerful" start.

[@savedpvtryan]

Could you possibly do a video on how cylinders work in unison and how they affect the motion of the other cylinders?

[@Franco.martinelli]

Great video, I understand how it works when the car is moving, but I couldn't understand what happens when the car is at a stop, is it because at that moment the rpm are too low to spin the transmission?

[@formula1nh]

I know this maybe a silly question, errmm you know the black casing, is that connected to the flywheel, so when the engine is revving, the casing will be revving, meaning the pump will be spinning? But the turbine wouldn't spin until it gets to a certain level when the fluid drives the turbine with enough power which drives the wheels. Just need to clarify on that. Thanks.

[@EngineeringExplained]

Yep, same idea.

[@ehiggins1016]

Great Video! I know more now then I did before watching it. Thank you

[@hugovillegas2750]

Love your videos! Really informative, you think you could do a video on torque converter stalls?