Torque Converter, How does it work ?


Most of us enjoy the smooth and effortless feeling of driving in an automatic transmission car The driving is effortless because you don’t need to worry about gear changing, and you don’t have a clutch pedal to operate in An automatic transmission car the work of the clutch pedal is automatically done by a hidden component Which is truly an engineering marvel the torque converter. The torque converter can even multiply the torque. Let’s see how this purely mechanical device performs its tasks Assume you are driving along smoothly, and you have to apply the brakes When you press the brake pedal the vehicles drive wheels stop turning This means that the drive shaft and the Associated transmission should also stop spinning But here comes the issue by applying the brakes you are not stopping the engine So at the time of braking if the engine and transmission are mechanically connected This would lead to a serious mechanical failure or the engine will stall You need a motion isolator for this purpose. this motion isolator is the torque converter? The torque converter is able to efficiently isolate the engine rotation from the transmission at the time of braking In normal driving conditions it transfers the engine rotation and power to the transmission Let’s see how it works This is a really simplified torque converter. It is basically a pump and a turbine immersed in transmission liquid The pump is directly connected to the engine so it always turns at the engine speed The liquid surrounding the pump will be pushed outwards due to the centrifugal force and it’s pressure increases The rotation of the pump adds a swirl to the liquid leaving the pump The turbine sits near to the pump and the high energy fluid coming out of the pump turns the turbine The turbine is connected to the transmission This way the engine power is transferred to the transmission via the transmission fluid? More specifically this configuration is known as a fluid flywheel When we introduce a component called a reactor between the turbine and pump it becomes a torque converter One of the main duties of the reactor is to send the fluid from the turbine back to the pump efficiently We will discuss more functions of the reactor later With this configuration even if the transmission comes to a sudden halt it will not affect the engine rotation Slippage between the pump and turbine is allowed here since they are connected by the fluid During normal operation the pump will be able to transfer motion and power to the turbine It should be noted that the turbine turns at slightly lower rpm than the pump due to energy loss in the fluid This is a simplified torque converter But you will never find this kind of configuration in any actual torque converter The pump and turbine of an actual torque converter is shown here In an actual torque converter the pump sits near to the transmission And the turbine sits near to the engine Let’s give proper colors to the components for better understanding Rotation from the engine is transmitted to the pump with the help of a cover The turbine output Rotation is transmitted to the transmission using a central shaft However, why is this arrangement made more complex than the previous case the answer for this comes from mechanical rather than fluid mechanics For the efficient operation of a torque converter the pump and turbine should both rotate in line with the crankshaft centerline The pump is directly connected to the engine crankshaft, so that will always be centered However, the turbine is independent of this unit this means that a bearing has to be used between the turbine and the crankshaft as Illustrated in order to make sure the turbine is also centered to the crankshaft In the current configuration one can achieve this quite easily however in the previous configuration This is very difficult since the turbine is far away from the crankshaft Now you might be wondering why this device which isolates motion is named as a torque converter This is because one of the most important functions of this device is to multiply the torque as the vehicle starts to move Let’s see how the torque converter does this The reactor is connected to a stationary shaft via a one-way clutch this means the reactor will be able to turn in one direction But not In the opposite For ease of understanding let’s increase the spacing between the components Now consider the situation as the vehicle starts here the pump is spinning at the engine speed But the turbine speed is lower and is slowly increasing This means that the fluid which leaves the turbine travels almost axially as shown This fluid when it hits the reactor blades will try to spin the reactor as shown But the one-way clutch in the reactor prevents this motion So what happens is that the fluid will be diverted in the same direction as the pumps rotation due to the stationary reactor as shown? In short the pump which adds swirl to the flow receives an already swirled fluid This makes the work of the pump easier and a greater pressure addition happens across the pump this highly pressurized fluid generates an amplified torque at the turbine and thus the transmission and the vehicle receives a greater level of torque as the vehicle starts to move However as the turbine speed increases The fluid leaving the turbine becomes more inclined as shown and at one point of time the inclined flow hits the other side of the reactor blades The reactor is free to spin in this direction so the reactor spins in the same direction as the pump and the turbine You can see that the swirl generation of the pump Inlet is lesser than the previous case And the torque multiplication ceases Here the turbine will be rotating at almost 90 percent of the pump speed This is a brilliant design As the vehicle starts to move when the driver needs maximum torque The Torque converter Multiplies the torque when the turbine attains a threshold speed the torque multiplication automatically ceases Thus the reactor plays a crucial role at the vehicle start? But without the reactor the torque converter will not perform well even in normal operation Let’s see why You might have noticed that the blades of the turbine are curved They are curved almost 90 degrees to absorb maximum energy from the fluid This means the turbine blades will always force the fluid to leave in a direction opposite to the rotation of pump and turbine due to this even at hide turbine speed the fluid swirl at the turbine outlet will be minimum If we do not use a reactor this very low swirl will affect the performance of the pump and the whole torque converter very badly With the introduction of reactor the flow gets diverted again, and the pump receives the fluid with improved swirl Even in normal operation you will find that the turbine turns slower than the pump in a torque converter This is due to energy loss within the coupling fluid To eliminate such energy losses modern torque converters use a lock-up clutch By activating this clutch during the normal operation The turbine will be mechanically locked with the pump unit and they will turn at the same speed This eliminates energy loss due to the fluid friction Before winding up the video, let’s summarize the uses of this brilliant mechanical device Thank you for watching the video and don’t forget to be one of our patrons

100 Replies to “Torque Converter, How does it work ?

  1. I thank Prof. John Kelly and Dr. Kyle for their technical inputs to this video. If you like our work, please support us at https://www.patreon.com/LearnEngineering .
    Prof. John Kelly's channel – https://goo.gl/7gpTzF
    Dr. Kyle's channel – https://goo.gl/txDKdK

  2. what about engine breaking? When engine-breaking, the turbine should spinning fast than the pump I guess??

  3. So the reason why an automatic can drive is because the transmission fluid is being turned so fast that it makes the other half of the torque converter spin with it, and when you brake, the fluid settles and it stops moving it?

  4. But what happens when you apply the brake, How the Transmission is isolated?
    The Pump will be in rotation as it is attached directly with the shaft and the fluid will be set in rotation and will force the turbine to rotate?

  5. Woah!! This video made me feel electric cars are far better than conventional cars in terms of efficiency!
    Also, I never thought that much amount of things were going inside a car. It's incredible. I will never look cars the same way I used to.
    Thanks.

  6. Woah. The power from the engine is transferred to the wheels DIRECTLY via pressurized fluid? Maybe I'm not getting this lol

  7. Meh, all that wasted energy due to the fluid, the manual transmission is far more efficient, mechanically simpler and more reliable, plus, most manuals rarely, if ever, require transmission fluid change, unlike automatics…

    I have an ‘07 VW Rabbit 5 speed manual with around 200,000 miles, still on the stock clutch and transmission fluid, try to get that life out of a bloody automatic, won’t happen.

    Plus the manual is far more fun and engaging in all driving situations except sitting in traffic…

  8. I was looking up adjusting differentials and ended up here.Never thought about how a torque converter worked till now.

  9. So when you stop at a traffic light and the engine is still spinning that pump, but you have your foot on the brake, what does all that fluid pressure/force do since it can't turn the turbine ?!

  10. Wow great vid.. I know how a torque converter works now. Whoever invented that shit is a genius!

  11. I immediately discovered an error in your video within the first couple seconds. Your animator accidentally put the steering wheel on the wrong side.

  12. Good grief my brain hurts! I think he is basically saying its gunna cost you money if its on your car!

  13. Torque converters are basically never a problem area in a typical auto transmission, right? I've never had a problem with one anyways. Do the lockup clutches ever fail?

  14. Great video. I couldn't imagine how trippy this would be if we saw the fluid motion in action via a transparent casing!

  15. Good afternoon, we are Brazilian, here we speak Portuguese. Help us by translating the videos of this beautiful channel. Another suggestion, why do not expand the work making videos, with simulations of the movement of electronic devices, electron, bits, and the conversion of electromagnetic waves to bits.

  16. They should stop making automatic transmissions and make everyone drive standard transmissions. It would probably drastically decrease the number of idiots farting around on their fricken phones!

  17. Here's simple explanation. Take 2 fans put them facing each other turn one on,you will see the one that is off moving from the air from one running. The turbines in converter do same thing only use fluid.
    I'm retired transmission tech.

  18. Every advanced technologies are innovations from hundreds of different earlier ideas which are evolving endlessly from relative implements and the money hunger of large corporations.

  19. 0:05 Is that a midget? He is so small. Best videos I've found on explaining this stuff, wonderful graphics! Fix the people!

  20. Not bad. Looked like you covered everything including the lockup clutch. How long does it take you to put one of these productions together?

  21. I tried telling my friends that its just fluid that couples the engine and drive shaft in a automatic transmission and they dont believe me.

  22. Hello ??, this is the best visual explanation I have ever seen on how torque converters do their magic! I'm 70 and a neighbor of mine back in the 1960s gave me a training manual on the newly introduced Ford C-6 automatic transmission ( I still have it) so I could better understand the trans in my 1966 Cyclone GT. It explained the whole principle of torque converters very well also and I have always understood whats going on ever since I read it. The one thing you did not mention that it talks about is how under high stall conditions the fluid speed gets accelerated in every pass through the pump, turbine, reactor and back to the pump. I have sent msgs to other people, converter mfgs, trans specialists etc asking if they knew how fast, what speed the fluid might attain in a full stall condition. I got reply's back several times but never really an answer to my question, as they said they really didn't know .
    Do you have any idea of an answer to this question, do you think it's ever been measured or calculated? I still have a cut open torque converter in my garage attic in case any one I know wants an explanation as to how they do their thing. This whole topic is why I feel in many ways that a torque converter hydraulic automatic trans is better than the dual clutch automatic / manual transmissions that are becoming so popular today.
    Sincerely, George

  23. If you can’t understand how a torque converter works, maybe you shouldn’t be working on cars…. How simple can it get?

  24. Thanks for great explanation.
    I can not understand why the use of torque converters are limited to automatic transmission and not considered in manual transmission systems. Is it for economic purpose or is there a technical obstacle for that?

  25. Can u explain will the return fluid from the turbine doesn't cause any obstruction to the flow of fluid from the pump??

  26. I've been working on Transmissions for 42 Ys and I'm 55ys old ,my family business is nothing but automatic Transmissions we never got rich and never will be but it's a good living BUT HARD WORK 💪,thank GOD for our Customers and people that trust us to do the best we can ,it is very hard work and our customers trust us, Edwards Brother's Transmission Roanoke Rapids North Carolina THANKS 😀 Louis Edwards JR

  27. Why is there a little child with a beard driving this car? Why is he on the wrong side of the csr yet the narrator is an American.

  28. Strange listening to an American accent while watching a right-hand driven car on the wrong side of the road. Or maybe I'm missing something here…..other than that, great video.

  29. Sooooo the main principle behind this is like a normal air fan on your desk blowing onto another fan and making it spin. Not by having the same shaft but because of the airflow. Smart but I think the energyloss between pump and turbine will always be there because of thermodynamics.

  30. Sir, my question is, can we use torque converter with electric motor and head drive, instead of gear box and couplings, in conveyor belt system?

  31. Shorter video, but well and easy to understood. And i found in many loss of power cases, are. caused by fault torque converter due excessively oil change intervals or low grade oil, leads its mechanism to scratch, higher heat range and greater clearances than designed between arranged moving parts. Thank you so much….!!!

  32. Great video but one thing not mentioned was that the impeller is welded to the converter housing where the turbine is not. Because the video shows the second half of the turbo housing with the turbine, one gets the impression that the turbine is attached or welded to the second half of the converter housing when it really free wheels.

  33. This is all WRONG.
    You have the pump and turbine backwards.🙊🙉🙈💥😩😵😞
    The turbine that drives the transmission is closest to the engine/flex plate.

  34. There are people who think they understand torque converters and hate them, then there are people who actually know what they are talking about and don’t hate then

  35. I don't get the operation of the one-way clutch. If I understand correctly, the reactor can't rotate in the clockwise direction in relation to the turbine (looking from the gearbox side of the torque converter) but it can turn anti-clockwise. So the reactor can't turn slower than the turbine because that would be in a clockwise direction. It can turn at the same speed or faster.

    Is there any scenario in the operation of the torque converter where the reactor turns faster than the turbine? This video doesn't provide such an example and it confuses me then why the rotor isn't simply coupled to the turbine shaft.

  36. Good video but it would be better if it was black and white, with a bit of grains and the narrator would sone like a 1940s Milton Friedman.

  37. Insert "This is real clever but I would like to let everyone know I'll stick to my manual; therefore I am a superior being" comment here

  38. I imagine a lot of trial and error were factors when designing this, along with the automatic transmission. Otherwise they were just super geniuses.

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