I used to have no idea how a torque converter worked, but after this video, I'm confused about fans too.

I'm 60 years old and I finally understand how a torque converter works. THANK YOU

I watched a few other videos on TC and was generally confused, but this tied it all together for me. You're a true teacher because you put thought into choosing words, examples and demonstrations that are practical and appropriate for the audience. Well done, you should consider a career in teaching.

If only our public-school teachers had a grasp on their subjects and taught as thoroughly as Eric.

That fan demo was genius! Very good job explaining this!

I've taken a college course on auto trans... this was much more informative in 20 mins than the 3 months it took my teacher to do nearly the same.

This is 9 years old and is better quality than some modern videos I watch. Well done.

You are so knowledgeable. You are a gifted teacher. As an engineer myself, I find your videos super informative. Keep up the great work.

Your practical gave me the "AHA!". 10/10.

This is by far the best instructional video of a torque converter I have ever seen. I am not a mechanic by any means, but his visual aids really lets you see how everything works. If Eric is an instructor in school, he must be putting out some "REALLY" good mechanics.

The Physics is so well done, I had a idea about this as a kid , but this is so straightforward 😊 Well done Eric 😂

My 1993 Oldsmobile started stalling at stoplights all of sudden. Thought I had a big problem. Finally got the car home after pissing off a whole lot of drivers behind me. Turned out to be the converter lockout solenoid. Part was $20, solenoid was under the transmission cover on the driver's side. Was a fairly simple repair and car was back to normal. A very small part that caused a big headache on the road. Excellent video by the way.

That was well done. I started out in automotive engineering. When starting out, there is a big difference in the rpm between the impeller and turbine. The impeller is then acting like a centrifugal pump accelerating the fluid to the outside and at an angle against an opposing angle on the turbine blades which are not spinning, making them a bit like a bucket on water wheel to extract some of the kinetic energy after which it is routed to the stopped or lower velocity inner diameter of the turbine, and back toward the inner diameter of the impeller where it will be sucked in and accelerated again. However, with the large difference in velocity and the opposite angle, the remaining kinetic energy opposes the impeller so there can be no torque gain unless you redirect and reuse that energy with a stator to assist the impeller. The stator attempts to rotate backwards and it cannot because the sprag/roller/one-way clutch doesn't allow it to, and it redirects the fast-moving fluid into the direction of the impeller at to further accelerate the fluid, which is where you get torque multiplication, ~2:1. However, as the turbine rpm gains equilibrium with the impeller, the turbine now produces its own back pressure from centrifugal force, thereby mostly balancing this out. However, with the angle of the inner turbine blades plus the rotation of the turbine being almost as fast as the impeller, the stator will now rotate with the impeller and turbine to give the best flow. This point is called couple or lockup, although it is not really coupled or locked up, but it will be less than 10%, slower depending on the converter, and torque multiplication will be 1:1. Thus, max torque multiplication occurs when the impeller is turning and the turbine is stopped. If something is wrong with the stator and it rotates in both direction, acceleration will be poor. If it won't move in either direction, it will add a load on the engine during coupling and cause heat buildup. Then came lockup torque converters where they actually do lock the impeller and turbine together physically, so they tend to refer to the former as couple rather lockup. The difference between a torque converter and a fluid coupling is the stator, which enables the multiplication of torque. So are fluid couplings obsolete? No. They are used in a lot of applications to isolate vibration between driving and driven members, and even gentle startups when an engine is running at a fixed RPM like electric engines and fluid is slowly added such as to start a conveyor belt with tons of product on it. The stall speed is the maximum rpm that the engine can turn when using all of its power against a stopped turbine. Logically, that depends on how much torque the engine has. While true, with something relatively heavy such as transmission fluid, small changes in RPM make big changes in torque to make a small rpm change, so it won't vary by as much as you think, which is why they can categorize them by stall speed. You can also see that the smaller the diameter, the faster you will have to spin it to equal the same outside velocity to achieve the same centrifugal force and pumping action on the fluid plus they have less area on the blades so a 1" difference in diameter can make a substantial difference in stall rpm. The stall rpm will vary more with torque variations as well, but still not by a lot. Of course the First Law of Thermodynamics states that neither matter nor energy can be created or destroyed. When the engine creates all of that high velocity fluid against a stationary turbine, the energy has to be dissipated somewhere, and it is. The engine horsepower is converted to heat, which is why the transmission cooler in the radiator, unless you have a wimpy engine in which fins on the outside of the converter and air holes in the bellhousing can do the job. Larger diameter converters are more efficient even during coupling. However, when overdrive transmissions and higher gear ratios became more and more popular, engine rpm dropped near or below where coupling would occur even at speed, so there were efficiency losses with more power going up in heat in the converter. This made the move to lockup converters compelling. From automotive engineering to aviation mechanic to military pilot, the engines made perfect sense to me right away because they use a stator to similar effect as torque converter except jet engines don't allow the stators rotate with the rotors because it is always pumping, unlike a torque converter, thus unnecessary. Another difference is the stators are where the compression is occurring when it converts the kinetic energy into static pressure, and redirects the flow direction into the rotor blades of the next stage. Torque converters don't compress the fluid but rather add to the kinetic energy to be expended against the turbine by feeding accelerated fluid back into the impeller to be further accelerated.

I have been a diy person all my life and worked on my own cars, I fully understood all about the engine function and how it all worked together but until now have never known how a torque converter worked and why it was needed, just took it for granted and never tried to understand it because i couldn't see inside the sealed unit and now it is exposed and the knoledge you have shared is priceless for people like myself. well done!!

I've watched you for almost 10 years and this is one of my favorite videos I have ever seen, in forms of technical knowledge and visual aid. I understood how TC's worked but could never explain it to another person myself. Always saw it as a compontent that just needed replaced as a whole and never got into the guts of it. Eric you're a legend

This was probably the most seamless explanation of an engineering concept I've encountered on youtube! Great job!

"i hope this video can help you in some small ways" dude. BIG. IT HELPED ME BIG. I NEVER understand how TC works but the fan demo you showed was really genius and that contributes to 100% of my understanding. Thank you ! you're the best !

Almost 8 years later this is still the best video on how these Donuts work. Thanks!

Simply incredible work Eric , I've been watching your channel for years. I also have taken an automotive electrical diagnostic class at a community college. Your work has been a great stepping stone in my automotive understanding In the past 5 years

Great tutorial! Back in the day Buick Dynaflows used the variable pitch torque converter you mentioned. Your concise explanations and demonstrations couldn't have been better. Crystal clear!

I'm a geezer and throughout my entire life (thus far) I've never had a clue how torque converters work. Outstanding video, I loved the two fans demo, excellent. Thanks a ton, now I can pass my thanks through a torque converter and virtually double my thanks.. so thanks two tonnes.

Eric - you are great at presenting things in an easy understandable way.

I am not a mechanic, i just like to know how things work. I watched this to the end and feel like i have actually learned something. Well done!

Best explanation I've seen so far of how a torque converter works. Really appreciate how you took a complicated subject and broke it down so that a layman could understand it. Your a good teacher.

I've seen tons of TC explanation videos but this one trumps them all, easily. Well done.

Thank you for giving clear information with no background noise and good lighting.

I appreciate your presentation. This is a subject that I had never looked into before, so it was all brand new to me. Before now, the torque converter was that big thing under the bell housing, between the engine and the transmission. You gave very eye opening information on precisely what is going on inside the metal shell. Thank you.

Dang man. That was a fantastic explanation of converters. Great job. Thank you. I bet it feels nice to still hear people getting help from your knowledge 8 years after you dropped it 🤘🏼🤘🏼

This is probably the best write up I've ever seen on TC operation. Awesome job Eric. The fans are a really nice visual aid.

This is amazing, your attention to detail and terminology, the clear and thorough explanations, that practical demonstration. You're an amazing educator!

Eric, you are a born teach Sir. For the first time in my life, I now fully understand how this unit work. Thank you so much.

What an excellent teacher. He always have the good way to explain and demontrate the ''How it works''. Brilliant man ! Thank you Eric, Merci !

Eric, this is a very lucid explanation of an automatic transmission. And showing all of the major parts makes for a great explanation. Thank you very much.

Awesome video! I've never really understood torque converters until I watched this video! Thank you!

Well explain. I knew this but needed a recap. U nailed it. Thank u bro

I appreciate your ability to explain and in detail so that even the least knowledgeable person can understand.

Having been a motorcycle mechanic the last 20 years I have had very little knowledge in auto specific things. This is a great explanation of how this works and the potentials of issues. Thanks for the video.

This video gives a fairly easy to understand explanation of how the impeller, the turbine, and the stator all work together in a torque converter transmission. Good job!

Eric, thanks for the simple analogies and demonstrations. I'm a long time car guy and the automatic transmission has long mystified me. This video enhanced my understanding and answered my questions about stall speed. Well done and thank you!

lifetime gearhead, past mechanic and auto enthusiast here. This is probably the best explanation of torque converters I have ever seen. Nice job!

Eric, you're way of explaining things is amazing. You're a genius!!!

Eric, you are a great teacher! That double fan setup made everything so understandable!

Wonderful explanation. I've long understood abstractly about the need for a stator, but here I got to see one and what it's connected to. Good work Eric. Thanks.

I'd just like to say thank you as your video over above all the others actually makes sense and describes in simple terms how it works and takes away the complication of the torque convertor and clearly represents a practical understanding to the novice of how it all works together.

I love the video I've never seen inside of a torque converter and understand fully how they worked you did that just like textbook classroom perfect thank you

I like the fan demo but the fluid passing through the stator is coming FROM the turbine and going BACK TO the impeller, not the other way around as you depict. The flow in the impeller goes in an in-to-out direction (it's getting spun out by centrifugal force) and enters the turbine at the outer edge. It flows from the outside to the inside in the turbine - it's called a 'radial inflow turbine' implying that the fluid travels radially inward - and exits closer to the centreline. Then it goes through the stator and back into the impeller where it gets spun out again.

Thank you for walking me through that properly. I kinda knew but you made it make complete sense. You're a good teacher man

Eric thank you so much, you are a top notch Car Professor for all us to learn. You make it easy to understand even the most difficult things. Thank you teacher...

One of the best explanations in KZfaq

well done ,easy to watch well explained without being too technical.Im a retired mechanic lecturer and I think this is far more imformative being shown practically which is esier to understand,well done again

Great video. Lots of prep, props and construction with some fine edits. It was all worth the end product - a clear, concise demonstration of how Torque Converters "work". Thank you for sharing.

Love the breakdown of the internals and how they work. Just amazing

No BS. Clear, concise, articulate, no jokes or talking to the dog. Well presented with fan analogy. Thanks for your effort and thoughtful presentation. Thanks for not wasting my time. You Tube channelers need to learn these techniques. I am subscribing.

By far, the best explanation I have ever seen for this. AWESOME!!!

Thanks Erick,very informative.A friend of mine had a Plymouth that he built an engine for.I think it was 400 ci,cam and a big carb.I remember when it was idling it would want to go.He said he believed he had put the wrong stall speed converter in it.His nephew totaled it before he got around to it.Your article was very easy to understand thanks.

I live in the UK and used to work in the Borg Warner in the transmission division in South Wales, I have built 1000s of the those converters and the stators and also put them on the dynormometer for testing. Brings back a lot of memories.

This was the most educational video on torque converters that I have ever seen. In fact, all your videos are so clear and concise. Thank you and keep being awesome.

Bloody brilliant. Everything I wanted to know. And I was asking myself about stall speed when you explained it. Cheers.

Illustrating your explanation using the two fans is brilliant. Many thanks for this most informative video.

Love how you break things down and make them simple to understand

Finally someone that speaks on my ability to relate and understand. Thanks. This was solid

Brilliant explanation and an excellent practical analogy with the 2 fans. Great stuff!

Great practical demonstration!

Excellent as usual, Eric! Clear, easily understandable on a somewhat (for some of us) complex piece of automotive technology. The fans are a great analogy. Thank You!!!

Thank You for that clear explanation of the 'HOW' a torque converter actually works. You Sir, are a treasure.

Thanks for the demo. I had a rough idea how this device worked, now I have a more complete understanding. Also it is interesting to see other technologies combined to make this work. The starter motor clutch on Honda motorbikes comes to mind. Great video.

Great job on your video. Simple explanations and visuals yet detailed enough to really grasp the concept of the torque converter. Love all your videos.

Brilliant explanation with the two fans! This is exactly how a turbine shaft engine works on helicopters. The Compressor section and turbine section are only connected by hot air. The expanding gases force the power turbine section to turn and power is transferred to the main transmission.

for not having a program or CGI to help u show what ur talking about. u did a great job explaining how a torque converter works. showed me something i didnt know. but wanted to know. thank u for ur time in making this video.

Dude! The fan analogy was genius! That’s the first video I saw that actually brought me close to understand how the torque converter works

Very simple and clear explanation. Thanks!

Eric you always teach me something of great value on every video! Keep it up ! It was great the way u used fans for a simplified visual.

I never really thought about how a torque converter worked. This was an excellent example. Perfect, Thank you.

This is a great video. Very thorough, but easy to understand. I really like torque converters, they are such a cool piece of technology, but they are also really hard to grasp exactly how they do their magic. Thanks!

Plenty of modern transmissions lock up the TCC in most gears, only unlocking to shift gears. It helps fuel efficiency and power delivery a lot.

Excellent, thank you sir. Great explanation of the Torque Converter Clutch.

Wow, that's the best explanation I've ever heard of a torque converter. From a UK viewer.

Came to this page through PCA. Great overall explanation, especially the high-stall converter for drag racing. Thanks.

Thank you for taking the time to teach this. I found it extremely informative.

I have a 2004 Volvo S60R whose torque converter just failed. Thanks for demystifying this for me!

I have a big diy job on this I need to get finished asap and not looking forward to it at all but after watching this video I feel much better about it thank you so much for doing this. You're an amazing teacher and have a new subscriber for sure.

And your example with the fans in EXCELLENT!

I had a general idea how they worked but never saw one apart. This was a very good explanation. You da man! Lol

Great explanation, there are a number of transmissions that will lock up in lower gears though not just high gear.

This came up on related videos and thank god I watch this because I had no idea how a Torque Converter really worked and how it look like inside. Very smart engineering. Great video 👍🏽 thank you .

The amount of ingenious engineering that goes into stuff like this will never cease to amaze me

Beautiful yet simple explanation, Thank you!

FIrst, I loved the " practical" with the fans -- it really demonstrates the concept. Second, some automatics designed for hauling heavier loads will use the lockup clutch in more than only the highest gear in order to limit heating of the transmission fluid.

WOW, this is a much-needed video to understand transmission operation and conditions. Thank you.

Best description of how a converter works I’ve ever seen thank you.

A super great video. 10 days ago, I had to add transmission shudder fix because at shifting lower gears, I had hesitation till I built up to top speed and gear. Now I better understand why the shudder fix worked for me. Thanks for the great video.

Eric is awesome.

Great explanation, Eric. The Torque Converter and the TCC were two things I didn't fully understand. Great video.

I have watched four vids hoping someone would touch on stall speed. Thank you for remembering to throw that in. Helped me a whole lot, especially after 4 vids worth of learning about the stator's function. Well done

That fan demo was genius , good job for explain this , thanks bro ;-)

Fantastic presentation, I've learned a lot, that I, was totally unaware. Thank you so much for explaining. You did a great job

Beautiful man, you're the only one who could help me, I watched 8 videos and yours was the only one that saved me

Thanks, Eric. I've always wondered just how a torque converter works. Very good explanation.

Man I had a hard time figuring out how and what the stater does you did such a great job here even i get it now. Thanks!!!!

Pretty amazing piece of ingenuity. It's still a little fuzzy how that thing works.