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How Does a Torque Converter Work?


Nis 14, 2020
How Does a Torque Converter Work

Here we have a torque converter torque converter it’s only found on an automatic transmission manual transmissions do not use for converters in the torque converter performs.

Three main functions function number one is it transfers power.

From the engine to the transmission function number to is it drives the front pump of the transmission is for those of you that saw that your did transmit the automatic transmission dissection video you know

That the the pump of the transmission fluid flow throughout the transmission and it’s basically the heart of the transmission such a pretty important function in the last thing the torque converter does is it doubles the torque output of the engine and we’ll get to how it does that in a moment but why don’t we start with the anatomy of the torque converter itself 

This is where the torque converter is bolted to the flexplate of the engine what that means is when you start the engine up the torque converter is spinning with the ended so as the engine spins this is bolted directly to the flexplate

Which is devoted to the crankshaft of the engine and it rotates at the same time the engine rotates transmission

This is the bell housing in which the torque converter so if you were looking at how this is mounted in here and torque converter is in this area in the front of the transmission and flip it around we can see a couple of those key components the first of which is going to be that input shaft of the transmission so this part is actually inserted into the torque converter there and that is what transfers power to the transmission 

This is our front pump assembly in this is actually spline to the Stater which we’ll get to in a minute but this is the front pump 

With the transmission in this is what’s Driven by the torque converter torque converter spins it drives this front pump says the engine is running the front pump of the of the transmission is running and sending fluid through out transmission once again.

That’s covered more in-depth in the video about the automatic transmission dissection but this will say four major components on the inside of it don’t start with that the first part which is the impeller.

Which is actually welded to the outside of the torque converter housing so the impeller spins with the engine so as the engine spins the impeller spins and so might look at this and say hey it looks just like a jet engine in a way it does in a way it’s sort of works in a similar way in 

The way it moves fluid through these veins here on the inside so as the engine is rotating it’s moving fluid through these Banks and as a fluid moves through these things he goes to a couple of different places it goes through the stator which is what this part here is into the turbine

Which is what this part here is we have one more part in this converter because it is a quote-unquote motor torque converter lock-up clutch assembly and this clutch assembly is attached to the the turban Otterbein this is attached to the turbo so these two pieces for sort of locked together and this area here is some friction material that under the right conditions causes it to lock up against the outside of a torque converter housing itself so as the engine is spinning everything’s going to spend this one I’ve got three major components in front of him.

I have an impeller which is welded to the inside of the torque converter housing Excel and Spins with Angie and over here I have a turbine which is splined to the input shaft of the transmission so if you want to look at this this will be the the torque converter on the outside of it and this part would be inside the bellhousing of the transmission is I showed you the input shaft passes through the impeller and spline up to Viterbo so you can see.

How these two things can move independently of one another and that’s really important and 

I’m going to show you how this relationship works with this really cool practical that I have here and here is our practical so in front of us we have to just read.

How Does a Torque Converter Work
How Does a Torque Converter Work

What is plugged in wall and has power going to it we’re going to call this one on pellet and we’re going to call the power going to it the one on the right is going to be so this one that does not receive power directly from the engine so when we start around you we can see that the movement at this case of the air that goes from one fan to the other causes the opposite fan to move now you’ll see that it doesn’t necessarily rotated exactly

The same speed there is some power loss here but there is power that is transferred from one side to the other just like in the transmission so this this side over here it would be our impeller driven.

By the engine and this side of here would be our turbine that drives the input shaft of the transmission at least two things work together so the fluid that passes through these veins once pass once it does that

What passes through the the impeller or the pump into the turbine it causes the turbine to move and here’s the cool part about what what a torque converter does text a friend since when you go to a stop light are you going to the stop light and you slowing down and you stop vehicle so the engine can still run but

It’s just not turning the turbine at this point but then when you go to take off I can start again tonight you noticed that when. 

I when I let go of the 2nd fan what would be the turbine it took a little while for this to go that’s because you really need like a punch to overcome the static inertia of vehicle sell a car when it’s just sitting there has a lot of weight to it and that way it equates to what’s called a static inertia so that the car now

That it’s at rest does not want to move so you got to get it moving but in order for this to work more effectively and more efficiently we use the stator okay so here we have our three major components again.

We have our impeller or stator and rotor turbine the stator is placed in between the impeller and the Turbo and what happens is when you take off from a dead stop the veins in this 

Stater actually cause the fluid that’s going from the impeller to the turbine to change direction you can see how do you say are placed in One Direction and then these twins are placed in the opposite direction.

So what what happens when that fluid changes direction is it increases its output in fact that’s what doubles the torque but it doesn’t do this all the time if it did this all the time I mean it would be kind of crazy but let’s talk a little bit here’s our front hub assembly that if you look at it would would be coming through the bellhousing and the stator spline to it just like that and what you’ll notice if you had this is it is it can rotate in One Direction but not in the other direction so I can spend in this direction just fine it’ll free will but whenever

 I try to turn in the opposite direction it locks up that’s because it has a one-way roller clutch or what’s called it a sprag clutch inside of your it’s very similar to like your 10-speed bicycle to where you can free wheel and you can just stop pedaling and then when you start to 

Pedal it locks up and causes it to spin what the reason this locks up is because the weight of the vehicle when the impeller is trying to work against it

When the impeller is try to work against the weight of the vehicle because of the stator to lock up and when it does lock up these fence stop in place and because of that they cause that fluid is passing

From this impeller to the term to change direction go like a hundred eighty degrees and when it does that it increases the torque output of the engine so you get that extra to get it off the line if you’ve ever had to push a car lots of you have to do this now back in the day I know GM had a version of a stator

That could actually change the output based on the angle of the spins so these fans could could move and it’s called a switch pitch torque converter I’m sure they still have something like that today

But those things really Multiplex work but because this fluid changes Direction in X stork hope that makes a little more clear so let’s let’s put our fans up here

 I’ll give you an idea okay we’re back with her fans again and we have our impeller here on the left and are turbine here on the right and tell her or pump and we have our I just put the input shaft into the turbine that’s the power going into the transmission so so the engines running you go to take off from a dead stop and this stator cause of that fluid to change direction does multiplying torque but then once it starts moving the second it starts moving the stator starts spinning.

But then when you come to a stop and you go to take off again the stator locks up doubles torque output but as soon as you start moving the state or start spinning again so the one-way clutch only works at a dead stop so it only multiplies Torque from a dead stop to get you going.

 Let’s talk a little bit about that for component the torque converter clutch how does this come into play as you can see behind in the impeller is moving the turbine for the turbine is not moving at the same speed as the impeller in this equates to power loss so you’re losing power.

 This type of system up with this situation is they’ve created the torque converter clutch or lock-up clutch or TCC up for it called the clutch assembly itself and this is the inside of the torque converter housing so what happens when you’re when you’re driving down the road in this is only going to be active like as you’re at cruising speed it’s never going to be active like if you’re at a dead stop or in any of the other gears it’s at the last year cuz

 I’m gay so so you got a 4-speed transmission you shift one two three four and then the lock-up torque converter clutch will kick in so it’s almost like a v in fact you can feel it many times well

It’s it’s if you we have our turbine which over here is driven and it sets inside the score converter clutch assembly if you wanted with the Springs do these Springs are there for when this thing applies you don’t want it to be a jarring apply you wanted to be like a softer if 

I saw those Springs there help dampen when the one that’s application happens but in essence what it what does torque converter clutch does is through fluid pressure The Descent many times do the input shaft of the transmission there’s pressure that passes through here and causes this to lock up against the outside housing of the torque converter what that means instead of you having a power loss.

That you have back here everything turns as one unit this way that power loss that you have here with just a fluid passing between the impeller and the turbine that power losses is negated because now the turbine is all part of the torque converter housing they all spend as one so it’s locked up so the lock-up torque converter is locked up and you come to a dead stop both fan stopped in the engine stalls so if you have a problem with your torque converter clutch it can actually cause your engine to stall when you come to stops and it does happen sometimes just sometimes stalling at a stoplight may actually be the torque converter clutch not disengaging when

 I said the fluid would pass through here I believe that passes through that passage right there and goes through the shaft and into the back of the house and now it also has to release like

 I said if it does not release it can actually cause your engine to stall how to torque converter clutch works and once again it it it doesn’t do this and any other speed other than a cruising speed so it won’t lock up in any of the gears as your shipping up through it will be after the last gear shift it into then the torque converter clutch won’t engage in order to prevent the power loss that happens between

The two here okay let’s review our is welded to the outside of the casing torque converter in spins with the engine running the impeller is always spinning in between that.

We have the stator the stator has the one-way roller clutch or spray clutch on the inside of it and when taking off from a dead stop that spray clutch locks up cuz of the fluids changed. 

Direction and as a result multiplies and torque output in the engine the turbine is driven by the impeller and you saw that there’s some power loss in between the two so to deal with that power loss we have a torque converter clutch 

Which is in some way fastened to the turbine of the torque converter and given conditions and given species torque converter clutch will lock up and cause the turbine to spin at the same speed as the case so it will lock the turbine to the case of the torque converter and everything will spend his one and you will.

Have lock up but those are the four major components of a modern torque converter older torque converters don’t necessarily have the the torque converter clutch but they do have the stator the turbine in the impeller torque converters I know some of you say that manuals for the wind you want to drive a manual transmission and you don’t want to mess with the complicated horsepower robbing slushbox and I get it over these things are out there and I hope this video and some small way is help increase your understanding of how does automatic transmissions work in particular the torque converter and something occurred to me before did the closing of

This video and that is stall speed in reference to torque converters in that that may come up somewhere along the line so what is stall speed stall speed and loose terms when that stator locks up and causes that torque multiplication to happen between the impeller and the turbine and usually it’s snowing passenger vehicles normal everyday driving vehicles and some around like a 1500 to 2500 rpm range and what that means is that the point like when you step on the gas.

Where you start to move because remember that torque multiplication happens when the resistance of the weight of your vehicle works against the fluid that’s passing between the impeller in the turbine and then that stator locks up torque is Multiplied to get that little extra kick to get you off the line well let’s say for instance in performance applications you want you want the stall speed of the converter to match the maximum torque output of the engine and I like when you drag racing so that when you take off of a lunch your engine is producing maximum torque so safe and a drag racing situation you would want your stall speed to be relatively high and you would want it to match the torque output of the maximum torque output of an engine you can probably find that with with Cam specs of the cam is of the engine is going to tell you when maximum torque output is going to happen find out when that is and get yourself a torque converter to me that has a stall speed to match that that work out.

But whenever RPM that maybe if you’ve ever driven one of those cars with a high stall speed converter and their there they’re much smaller than the higher the speed the smaller the converter get so big converters have low stall speeds and small campers tend to have higher stall speeds.

But if you ever driven a car like that and you try to drive it normally like taking off from a dead stop you got to hit the gas and nothing’s happening so you have to rev the engine up until that like 4,000 RPM Ranger whatever for that thing to finally take off but when it does takes off like a bullet it just cuz that’s that’s

The way it’s designed so much but that’s that’s one of the philosophies behind and that’s how stall speed relates to torque converter soap that little bit of information helps round out this video as far as the information 

That was in it but I hope that that the information found in this video and the Practical of these two fans give you some understanding of how that power is transferred from the engine to the input shaft of the transmission via the impeller and turbine inside there and also a bit about how that torque converter clutch.

 Works remember if that torque converter clutch stays stuck and then it could possibly start your engine when you’re coming to a stop or cause some kind of shutter at times there’s lots of things that can cause a torque converter clutch is one of those things but also remember that the torque converter clutch will not be active until you shifted through.

All your gear so you’re in your highest gear you got no place out nowhere else to shift then the torque converter lock-up to it to minimize that that power loss that happens between the impeller in the turbine naturally as you can see because the turbines not going to spend at the same rate as the impeller does just.

Because of the flu there it has to move that fluid for there so there’s no direct connection until that torque converter clutch locks those two things together but anyway I hope this information was helpful and useful to you really really do take to so if you have questions or wanted to discuss further there will be a link in the description to a forum discussion about addition to you can post comments below and I will answer.

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