Questions & Concerns Regarding ATS Triple-Lok

[Un-Hemi]

"Surface Tension... The cohesive forces between liquid molecules are responsible for the phenomenon known as surface tension. The molecules at the surface do not have other like molecules on all sides of them and consequently they cohere more strongly to those directly associated with them on the surface. This forms a surface "film" which makes it more difficult to move an object through the surface than to move it when it is completely submersed. " Pirated directly off the I-net.



What this means is that when I open my eyes wide, my contacts don't fall out. If I open my eyes wide under water, my contacts are history.



Surface tension causes a clutch plate to stick to the workbench when there is oil underneath it. Drop the clutch plate in a bucket of oil and there will be no surface tension, and it won't stick to the bottom of the bucket, because there is oil completely surrounding it, just like inside a torque converter.



Just my $. 02. (that's $4. 95 Canadian!) :{

 

[Strick-9]

Tommy,



Good answer. Seems like a powertrain engineer would know that though.



fest3er,



Keep looking at those schematics. I think I found 5 or six errors before I got frustrated and closed the book. It's sure hard to learn from a flawed textbook isn't it.



I've got another question for everyone about this design. It doesn't look like an outside vendor can post because its against the rules. It doesn't look like ATS will post because they think that we're attacking them. But I still want to learn, so maybe the rest of us who are still interested can put our heads together and figure this out for ourselves.



I haven't fully accepted the fact that flow in one direction will move a piston on to compress a clutch pack and flow in the opposite direction will push a piston off AND equally separate friction and steel plates.



So let's think about where the fluid is going during fluid coupling.

It's entering the TC through the input shaft. It's exiting between the stator reaction shaft and the input shaft, but that's not important. The fluid entering the TC is flowing outward through the frictions and steels and going AROUND the piston correct?



So it seems that when the piston is fully OFF the front cover we have some amount of clearance for flow. I don't know that number so I'll just make one up. I'll guess it's 1/2".



So we only have this 1/2" to deal with. I see two possible scenarios. In the first scenario we have 3 gaps each 1/6". Nothing is rubbing or dragging.



In the second scenario, all frictions and steels are dragging and there is ONE gap somewhere of 1/2".



This seems to be the big debate here. Is it scenario 1 or 2?



Several people have stated that a continuous oil supply and or centrifugal force will tend to separate all the moving parts. I need one of you to explain the physics of that to me please.



There is a steel between each friction. Each steel has outside splines into the front cover. Each friction has inside splines to the spinning turbine.



So the fluid doesn't just flow outward through the steels and frictions. Now matter which path it takes, it has to make its way between the splines to get through. It can either travel along the inner splines between the where the frictions are connected to the spinning turbine, or it can travel outward first and then through the splines where the steels connect to the front cover.



Now if there were ANY restriction at ALL as the fluid travelled through the splines, there would be a pressure drop. That's simple physics. If you try to restrict a garden hose with your thumb, you have to press hard because the restriction is building a pressure drop at your thumb. This pressure drop applies a force to your thumb to try to move it.



With that in mind. How is there NO pressure drop across that first steel plate (the one closest to the front cover)?



Or maybe I'm missing something. All right guys (or girls), your turn. Teach me something.



-Chris

 

[dramer]

Triple-loc

We are working on a basic drawing for the general public. This is kind of a hard spot without letting out product design. Tommy that was top notch on your understanding of the oil & surface friction coefficient to surface. We will be posting much more please hang on.

 

[Un-Hemi]

I don't understand what all the fuss is about. In the 47RE there are various clutch packs not applied in various gears. If wear was a problem in a disengaged clutch pack, all the friction material would be in the pan. It just doesn't happen. What makes the torque converter any different? Maybe I just don't get it.

 

[dramer]

Triple-lok

Originally posted by TommyTurbosaurus

I don't understand what all the fuss is about. In the 47RE there are various clutch packs not applied in various gears. If wear was a problem in a disengaged clutch pack, all the friction material would be in the pan. It just doesn't happen. What makes the torque converter any different? Maybe I just don't get it.

Tommy thats just it YOU DO GET IT. Your 100% Correct!!!!!

 

[Strick-9]

There is no other clutch pack in the transmission where fluid pushes the piston OFF and holds it off by flow through the pack.



That's the difference here.



Using the factory lockup system (flow through the pack when disengaged), you cannot mimic the clutch packs of the rest of the transmission.



I'm happy to hear we may get the flow diagrams. Thanks Don. Maybe that will explain it all to me.



-Chris

 

[Un-Hemi]

Is there really a holdoff pressure, or is it a pressure balance on both sides of the lockup actuator... . piston? (or whatever it's called)



I see it as a pressure balance that is removed for lockup. In the hydraulic schematics it appears that in 4th gear unlock, there is converter lube pressure (5-57psi) fed to both sides of the lockup 'piston' inside the converter. In 4th gear lockup, there is line pressure (95-130psi) applied to one side of the actuator, and the other side has somewhat less than converter lube pressure (5-57psi), because of an hydraulic restrictor that shows in the 4th gear lockup schematic just above the L/U switch valve.



Note: I didn't use the third gear schematics in my explanation because I believe the '99 manual's 3rd gear lockup schematic is flawed in the area of interest.



The hydraulic schematics in my '99 service manual are so poor in detail that it's difficult to discern what moves and where the pressures are, especially with the apparent glaring errors. Sure wish I'd paid more attention to the cut converter at Dyno Day!



What say you?

 

[fest3er]

Originally posted by TommyTurbosaurus

Is there really a holdoff pressure, or is it a pressure balance on both sides of the lockup actuator... . piston? (or whatever it's called)



I see it as a pressure balance that is removed for lockup. In the hydraulic schematics it appears that in 4th gear unlock, there is converter lube pressure (5-57psi) fed to both sides of the lockup 'piston' inside the converter. In 4th gear lockup, there is line pressure (95-130psi) applied to one side of the actuator, and the other side has somewhat less than converter lube pressure (5-57psi), because of an hydraulic restrictor that shows in the 4th gear lockup schematic just above the L/U switch valve.



Note: I didn't use the third gear schematics in my explanation because I believe the '99 manual's 3rd gear lockup schematic is flawed in the area of interest.



The hydraulic schematics in my '99 service manual are so poor in detail that it's difficult to discern what moves and where the pressures are, especially with the apparent glaring errors. Sure wish I'd paid more attention to the cut converter at Dyno Day!



What say you?

Tommy, I would ahve to say you are near correct. The 3rd schematic *is* flawed, in that the symbol for the 3rd lockup solenioid should be closed; instead, int eh manual it is open. That is the error to which I refered. You get a gold star!



Essentially, according to the schematics, high pressure is applied to engage the TC lockup. When released, there should be equal pressure on both sides of the TC, thus allowing the plates to float.



That equal pressure means there is no 'release' pressure, as Bill K. has been hinting all along. So, is the SM wrong?



Fest3er

 

[Un-Hemi]

Good one, Neal. I agree; in the 3rd gear lockup diagram the lockup solenoid should look like it does in the 4th gear lockup diagram.



Do you think that the torque converter in the 3rd gear lockup diagram should look like the one in the 4th gear lockup diagram, with line pressure inside it? It would appear to make more sense that way.



'Release pressure' might be better named 'float' pressure, if my understanding of the operation of the lockup clutch is correct.



The torque converter in the 4th gear unlock diagram appears to be incorrect also. (no converter lube pressure shading)



Strick-9, you're correct about all the errors!



Darn! So many edits!

 

[Strick-9]

If it were merely a pressure balance, why would any piston move off the front cover. Stock or triple disk? When running in lockup we have line pressure on the apply side and lube pressure on the release side. Straight from the service manual.



Then, when the switch valve cycles, it appears that the pressures are equal. Why then would the piston move? If the pressures were equal, the piston would just sit there dragging and never release off the front cover.



There is flow through the converter in one direction, fluid coupling. In lockup, the piston seals against the front cover and prevents any more flow. That flow through the converter in fluid coupling has to move the piston off the front cover. To do this, there has to be a restriction around the piston's outer edges. Since there is a restriction around the outside of the piston, then the pressure isn't equal on both sides. The same force that physically moves the piston away from the front cover is still present.



So now we get back to the original question. What are these pressures? Apply? Release?

 

[Un-Hemi]

Well, this is just speculation 'cuz I are just a hobby-mechicanic, but when line pressure is removed from the one side of the lockup clutch, it will float away from the front cover, much like any other hydraulic clutch releases, because there is no pressure imbalance to hold it there. As soon as the clutch begins to release, (slip is a bad word here) oil will migrate into the space between the clutch disk and the front cover. The oil film only has to be of molecular thickness to provide almost frictionless lubrication.



The diagrams in the manual are poor, but I don't recall seeing any seal around the outside of the clutch disk. Does the clutch lining act as its own seal? I'm thinking that it might; like one of those flat, round tub stoppers that uses the pressure of the water above it to hold it in place. Again, like I said, I wish I had paid more attention at Dyno Day.



I've been told that automatic transmissions leak like sieves internally. Is it possible that there is some engineered (or non-engineered) leakage past the lockup clutch to allow for some flow? Do you need much oil flow in a locked-up converter? There's no heat being generated in lockup. Is there a great need for internal lubrication in lockup?



I know... More questions. Without having a cut converter to look at, I'll defer further comment until more information is shared.



Chris, if the lockup clutch operates the way I believe it does, the pressures are as stated earlier: The apply pressure differential is probably something approaching line pressure, according to the diagrams. If you're willing to accept that when the converter is not locked up, there is 'converter lube pressure' on both sides of the lockup clutch, then the 'release' pressure differential is effectively zero. The converter lube pressure is still 5-57psi, but that's the pressure everywhere within the converter, including on both sides of the lockup clutch, much like the air pressure that surrounds us now.



Again, this is only speculative information deduced from past experience with torqueflites and current experience with inaccurate manuals. We're all here to learn; myself included! Apologies for the long post. Need a smilie for ZZZZZZZZ.

 

[B KIRK]

Here you go. Copy this one.

 

[Strick-9]

Tommy,



Is the air pressure equal on all sides of you when a wind gust blows you? Why does a strong wind gust blow a hat off your head?



Think about flow not just pressure,



If you were standing in a STRONG wind gust. One where you actually had to lean into the wind to keep from being blown over. Where would you measure air pressure. In front of your or behind you. Would it be the same? If so, why are you leaning forward?



Chris

 

[Un-Hemi]

B KIRK, thanks, I needed that!



Chris, great minds think alike. I was going to use the analogy of wind in my description, but chose not to. Actually, if you were facing into a strong wind, you would be hard-pressed to measure the miniscule pressure differential between your front and back. Most of the resistance you would feel trying to blow you over would be because of drag. Streamline yourself and you would not feel as much drag. But I digress.



I think the converter requires fluid flow only to carry away heat and contaminants. It requires internal pressure to prevent cavitation of the fluid when it's operating in fluid coupling. It requires a pressure differential to activate the lockup clutch. That's the way I see it, and I stand to be corrected.



Once you get through the errors in the hydraulic schematics, the operation seems evident.



Unfortunately, I have neither the time or my service manual to carry on at this moment. In fact, this topic would be better hashed out over a beer and at a table with hydraulic schematics in hand. It's gonna take too long to get past all the details and others may lose patience.



I asked several questions in the third paragraph of my last rant and they're still out there to be answered. We'll get it figured out eventually.

 

[fest3er]

Originally posted by TommyTurbosaurus

... I think the converter requires fluid flow only to carry away heat and contaminants. It requires internal pressure to prevent cavitation of the fluid when it's operating in fluid coupling. It requires a pressure differential to activate the lockup clutch. That's the way I see it, and I stand to be corrected. ...

So, can we say we have a basic understanding of the 'static' operation of the TC? That is, we know the actions taken to engage and disengage the clutch. Now we need to consider the TC as a dynamic system, with dynamic, turbulent fluid flow inside.



Ponder that when the convertor is unlocked, there is a certain amount of fluid pumped through it. But isn't there a *lot* of fluid being pumped around *internal* to the TC, far more than can be pumped through the main shaft?



Now consider the direction of this fluid flow. I think there would be fluid being pumped from the center of the impeller to the outside, where it is 'sent' to the turbine. But some of this fluid should flow 'inward' past the plates, because the impeller pumps more fluid than the turbine can accept. (If the turbine always took all of the fluid the impeller sends, we would have 100% coupling, which would negate the reason for having the TC in the first place!)



Combine that inward flow with the force of fluid being slung outward when the TC is turning rapidly. I should think that turbulence would cause enough pressure to force the plates apart.



If you were to lock up the TC when the engine is not running, there would be no pressure to force the plates apart; thus they could drag. But as soon as the impeller starts turning, there is significant turbulence inside the TC to force the plates apart.



Have I made any sense here?



Fest3er

 

[Un-Hemi]

Yes, Neal, what you say makes sense. There is a lot of fluid thrashing around in the converter. Remember, though, that the lockup clutch is not directly in the path of the fluid flow between the 'pump' and the 'turbine' in the converter housing, but is between the turbine and the front cover.



To minimize confusion (and there's probably lots of it), I respectfully suggest that we use the conventional names as defined in the site below, which illustrates the operation of the torque converter.



http://www.howstuffworks.com/torque-converter.htm



Pump, turbine, and stator. Note that the 'pump' part of the converter, driven by the engine, is closest to the transmission, and that the turbine is closest to the front cover. I learn something every day!

 

[South Bend Clutch]

A quick question here... I hope I don't sound stupid but I am just trying to learn.



I build manual clutch packs anywhere from single disc to triple disk for oil bath units. I know it is not the same with (lock up and unlock up) but some of the principles are the same. Using what Tommy said at the top of the page with sticking on a flat surface and not in a bucket of oil. With the oil bath clutches that I do, understand that the clutch pack is completely submerged in oil... if the friction surfaces are perfectly flat, with the pressure that is applied the oil will be squished out of the contact surfaces thus causing the friction surface to stick to the drive plates, not with suction but enough to drag. How that problem is remedied is the friction surfaces are not perfectly flat. We refer to it as a kind of marcel, a slight wave in the friction surface to act like a spring to free the plates from one another. When compressed it will lay flat but when relieved they will separate. Could this theory work in the TC as well? Or maybe it already is?

 

[Strick-9]

Tommy,



In your description of the TC operation. My only question to you is where does the pressure differential come from? You say a pressure differential is required to move the piston. What causes this pressure differential. You have flow going through the converter in one direction and then that flow is reversed when the switch valve cycles. During this short period of time before the piston seals and line pressure builds up on the apply side of the piston, what is causing it to move?



Pressure doesn’t just occur. You have to have sufficient restriction to build up that pressure. Pressure is just a restriction to flow. Simple as that.



If you connect a 70 psi fuel pump to a garden hose with no restriction, it will not produce 70 psi. It will only produce a few psi to make the fluid move down the hose. If you put a restriction on that hose or cap the end, then pressure can build up to 70 psi. Do you agree with that?



Fest3er,



Do you realize that the piston, frictions and steels are in front of the turbine/impeller, not inside it? Wasn’t sure by your description. I took a picture of the hub that drives the forward clutch in our trannies. This clutch is engaged when we are in a forward gear. Notice the holes drilled in the outside directly above where the clutch pack rides. If the presence of fluid and centrifugal force would force the clutch pack apart and eliminate drag, why are these holes drilled here? Surely you agree that it cost money and time to add these holes. Also, these holes weaken the strength of this hub. Why then you do you think that the engineers went to the trouble of adding these holes? It must have been awfully important to make those sacrifices.



#ad






-Chris

 

[Strick-9]

Peter,

As long as it can seal 100+ psi of pressure, I don't see why it couldn't be used. Thanks for sharing.



Now if there just wasn't a constant force, pushing them back together.



-Chris

 

[South Bend Clutch]

. Strick-9,



If the force is not that great wouldn't a few small springs remedy the problem? Floater springs between the center plates that will collapse easily when the clamp force is applied and enough to allow the plates to come completely together. Counter sunk.