Long story so have a cup of coffee and some time. I don't fully understand what is going on with this problem and would welcome any input. I've got a customer with this machine Sn. JML0036. They changed the engine while leaving the torque converter hanging in the machine. They put the replacement engine in the machine got everything running and the converter would barely turn the drive shaft. Machine would go into gear and the drive shaft would lock up and there wasn't any torque applied and the machine wouldn't move. All the transmission pressures checked out as confirmed by the Cat dealer field mechanic who said something is wrong in the converter. They pulled the converter out, tore it down, didn't find anything obvious, put it back together and in the machine with the same result. They checked for an exchange or even a new converter and were told that this particular converter has been discontinued and is no longer available. They called me for some troubleshooting and opinion and just like before the pressures were there. The only odd thing was torque converter outlet pressure was about the same as torque converter inlet pressure plus the output yoke seal was leaking. I'm figuring that the drive line still should turn but it was just limping along. They tore the converter back out of the machine and I came in to help dismantle the thing again. The output shaft has two seals that seal a land where oil is fed from the torque converter case into output shaft and down its length and up into the stator housing and into the cavities of the impeller and turbine. One of those seals was damaged, possibly when the shaft was installed. We didn't see much of anything else wrong. I did see one odd thing to me in that the stator is different than any I've worked on in the past. We went into SIS to find that this particular converter has a free floating stator and a lock up clutch. The lock up clutch isn't part of the problem in that it locks the turbine to the output only under certain conditions. On the stator there is basically a sprague clutch inside that will lock it to a hub when the turbine has a load against it. When I checked it as we pulled the converter apart the stator would turn either way on the hub. I'm perplexed by this. Anyway it was torn apart, inspected and reassembled by the instruction in SIS. When done it worked the way the book said it should. I think it could be a problem if oil wasn't directed back to the impeller but think it all should have turned the impeller and drive shaft anyway. The other perplexing issue is that the turbine connects outside on the flywheel side to a ring gear with a planetary inside it. The hub of the planetary carrier is connected to the output shaft. If you spin the output shaft by hand, the planetary carrier just spins in the ring gear. If you spin the ring gear, I can feel the turbine turning inside the converter housing, but the planet carrier doesn't turn, just the planet gears do. Apparently the turbine is supposed to spin the ring gear which spins the planet carrier and apparently there is supposed to be enough force to make those planetary gears not spin around inside the ring gear? There is no sun gear on the output shaft to positively connect that ring gear to the output shaft? We put the whole thing back together by the book and installed it in the machine yesterday. They are finishing the wiring and cab stuff and reinstalled fluids today and we are going to fire it up on Monday. I hope it works but am pretty nervous because I don't fully understand all that is going on in this thing.
The one-way clutch was foobarbed. That's the usual mode of failure - the spring/roller mechanism fails and the stator will not lock in place against the force of the oil flow through the converter when required to do so. It works exactly the same as a ratchet wrench. Locked in one direction of rotation. Click, click click, in the other. It's just the same as a truck with an LUC. When the LUC is engaged the spring/roller ratchet mechanism permits the stator to "freewheel" so that it turns with the converter. In torque converter drive the mechanism has to lock the stator in place so that it directs oil at the correct angles between the impeller and the turbine. I've never come across a freewheel stator in a Cat tractor before, but in a wheel loader the failure of the FWS was usually accompanied by first reports of a lack of engine power (in fact nothing to do with the engine) or in an off-highway truck often the complaint would be a failure of the transmission to upshift correctly. Question: When the converter was rebuilt with new parts did the one-way stator clutch work correctly.? It's a bit late now but I'd have been looking very closely at the condition of the shaft surface where those two rotating seals you mentioned that were found damaged. Also the lack of a difference between converter inlet pressure and outlet pressure is strange. I'd be interested to see what the pressures are when it's tested after having been rebuilt.
Hi John explanation of torque divider operation
and more
Mark250; Your illustration shows a sun gear on that torque divider. I mentioned that on the machine we are working on that there is no sun gear. I checked the parts book first thing because of that and it does not show a sun gear for that planetary or a place to even mount one in there. I checked both the planetary page and the flywheel page and neither showed a sun gear. Perhaps I'm missing something here and maybe someone could check SIS under the serial number and see if we are missing something on that line. Nice; When I pulled the stator out and unit would turn on the hub either way. I pulled it apart to make sure the springs were in the right orientation and that the hub and cam rings didn't show any wear and that the rollers were in good condition. I reassemble it and it checked out proper in a manual test. I was also thinking that even if that did freewheel that the drive line should still turn. The case would still be flooded and oil would be pushed by the impeller into the turbine. I think the result would be low power and probably overheating.
I can check but the S/N in your OP is missing a digit after the JML prefix. Not sure if it makes a difference or not.
It’s 346.
Is it Ref #3 at the bottom LH corner of the illustration below.?
That piece didn't show in the illustrations that I've seen in SIS. Do you have an illustration number or something I can go off of in the morning? What is the description for the circled item and the rings on either side?
The circled item #3 is described as a sun gear. Keep an eye on your PMs.
Super! That solves the whole mess I think. I'll keep my eyes open. Thanks!!!
I was going to say that I had a customer install a torque but they left the sungear out. It did the same thing as you describe. Somebody has the sungear laying under their bench. It would have come out with the engine. It is snapringed into the flywheel.
It was swapped with an exchange engine so I think the gear is gone. I’ll know more tomorrow morning. Thank you all for the help!!
Wonder if that same *somebody* is going to foot the bill for multiple R/R of this torque converter.
I sent you some more info. Need the S/N of the replacement engine to check if the flywheel P/N is the same as the one from the engine that was removed. The toothed recess for the sun gear looks deeper, and I'd bet the flywheel on the replacement engine doesn't have a snap ring groove either.
Can I be the first one to ask why in the hell do these machines have to not only be so complicated, but why this missing gear wasn't being shown in whatever John was referring to?
It is my understanding that the people who did the swap are not currently working for the owners of this machine. If you look close at the diagram that Nige posted you will see just a plate with no indication of a sun gear showing at all. I don't recall if I looked at it directly and didn't realize what it was or it just wasn't part of the diagram that I saw. I agree on the complexity.
Make sure there is a pilot bearing in the flywheel too the next time you have it apart. Would be sad to have a torque failure after all this.
Pulled the converter housing back out of the machine this morning. Flywheel has a place for the sun gear carrier plate to engage the internal teeth plus it has the retaining ring land. There is also a place for a pilot bearing and a retainer ring. The parts are ordered and supposed to be here tomorrow morning. I looked the engine over for some kind of ID tag and found nothing. The DPF and associated furnace sitting on top of the engine covers the valve covers of the engine completely if there is a tag there. The sides of the block have nothing on them either.
Clutching at straws but is there any chance there is a S/N on the invoice from when the customer bought the engine.?
I'm going to try fit the gear and pilot bearing in the morning when I have them in my hands. If they work I'll install the converter in the morning. If they don't work I'll do what I can to get the numbers. Thanks
Very interesting thread this.Am I right in thinking that this engine has just been replaced by previous fitters and bits have been forgotten that should be in the torque????? Surely I’m reading this wrong? Is it an export job to the moon or some other far off job.Eitherway it’s landed you with a bald spot where you’re scratching your head and I find it incredulous. Good luck with it all John C,seems like you need it
Do this have the 3 springs between the flywheel and the sun gear drive plate like the older torque dividers do ? Bob
Hi Nicky, yes you are correct. These kinds of jobs I like to do and am known for getting involved with. They are the result of all the young people coming into the business. None are trained but are willing to get their feet wet. Problem is that it takes more than willing to work attitudes to do this kind of work. Luckily the job is not far from home and the machine was inside a shop when the engine locked up. I'm working inside on this one. Thanks for the comment and well wishes.
From the parts diagram it looks like only just a drive plate with a sun gear attached in the middle. The drive plate has outside teeth that fit in the flywheel and is held in with a snap ring. The planetary also has four gears in a rectangle orientation instead of the older three gear type planetarys.
Attached are some photos of the setup.
Here are a couple of photos showing the flywheel without and with the sun gear.
Here are a couple of photos of the mess that resides under the cab.
Here is a photo of the of the only tag that I could find on the engine. We finished the install today. The machine now moves as it is supposed to.
BRAVO!!
A Cat Reman engine then.? 20R-9358 is a good Part Number. Serial Number appears to be FYE00106 or 196. The photo's a tad hard to read. Glad you got it working.
So this is the first torque divider you've seen the inside of? Bob
Well done,glad you got to the bottom of the mystery.It’s almost too bizarre to take in,and I can easily understand that it’s taken so much effort in getting the parts book out and really getting to grips with it.It’s almost been too obvious to be obvious at all!!!! I’m no fitter,but I guess it’s hard to have such a viariaty of different machines to fix.When Tony comes out to my stuff,he allways brings his pile of books even though he’s doing it day in,day out.That’s why I allways ask him to do things for me.This D6 you’ve been putting right clearly has allready had a number of fitters trying to get it running to zero avail. Perhaps,it wasn’t their first rodeo,but complacency has crept in and they’ve missed the very basics of their profession. You,clearly,have not. You can come and work for me anytime
I've done about a dozen of them thirty years ago. Those were all D8 and D9 dozers. I've also done plenty of converters in haul trucks and wheel loaders from multiple manufacturers. The issue was in listening to the story and not recognizing that the drawing did not have the appearance of the sun gear. The Doh! moment was in seeing the training drawing above and Nige sending the parts diagram with the sun gear circled. Thanks nicky 68a for the confidence. I was told today when I got done that there were five different people who worked on the machine, not including me. It was pretty much all their first rodeo on D6T machines. Age ranges were 25 to around 36. None came from a dealer background. We discussed the issue of wrenches that were over 40 are just not available today.
So let me see if I have this straight. The people that pulled the original engine left a HUGE sun gear or ring out when the replacement engine was installed? How does something that large get overlooked? Wouldn't it be lying somewhere in sight?
5 people and R@R not so much by committee but more of a disconnected tag team.
How many people on here have pulled a D6T engine? How many here have had to remove and rebuild one of those torque converters? Things that are obvious to those of us in the business for years, may not be for those just starting out. It was an expensive bit of education on the part of my customer and likely not to be forgotten for a long time.
I get that but we are talking about a large piece being overlooked that was originally there. I just can't believe even novice techs not noticing something like that. I would have had a fit
The Sun Gear drive plate on the earlier D6's had an alignment mark on the flywheel and the index teeth for the correct position, plus the springs behind it to keep it trimmed up to the snap ring, the shaft through the converter runs on 2 bushings that should only be fitted with the oil feed groves angled in a set position, it was very common to find them facing the wrong way, sad to say I would have spotted the missing bit in a second, but I have done heaps of drive dividers and can see how the missing bit was left inside the failed engine, anyhow with the cab off and all the bolts easy to turn it's not long to sort. tctractors
This unit is a 2017. The shaft is drilled instead of having a groove and needing timing on the hubs. The thing is just different enough to be confusing. There were no springs or index teeth in the drive plate. It looked like a different design from what I worked with years ago. I knew something was missing but couldn't put my finger on it to start with. The kids had no idea when they were swapping things. The parts drawing in SIS is not much help either. It shows the wrong side of the plate. If it showed the sun gear side, it would have been obvious. At this point it doesn't matter how it happened and the only people who were a bit irked are the owners. They hired the kids so the issue is on them and they know it. At this point they are happy this issue is solved and they can move on. There are plenty of other issues for them to put emotion into.
I agree. Below is a parts illustration from a different S/N prefix D6T.
One thing I have learned and taught my 20 year old son, when going into an unfamiliar machine, take a few pictures with the ever handy cell phone, just to serve as a reminder of what it looked like as it came apart. One never knows what interruptions will occur before you go to reassemble things.
Wise words.Those interruptions can be a disaster. Whenever I service one of my tractors,I leave the dipstick on the seat until the job is complete to make sure I’ve put oil back in it
I understand your situation as it's not a good thing having to many people doing a bit, by the way it's not the shaft that has the angled grooves in it's the bushings, if the torque has been worked on it's money on that the bushings have been fitted with the grooves facing the wrong way, anyhow Nige is a sharp chap and Wizard on detail plus just a great chap to boot, as you said the owners are happy to get the matter resolved and put the tractor back to work, all this extra work at least gives a knowledge benefit to yourself and anyone reading this interesting subject, we will be into the Nitrogen cylinders next on the D6T's. tctractors.
I can easily see it happen. in my shop it’s not unusual for one person to pull an engine or torque converter or transmission, send the component down to the rebuild shop, and get it back several weeks later and another person put it back in (original mechanic on vacation or quit lol) and stuff could easily get left off
The bushings were not changed. Things looked near new when the torque was dismantled. It got new seals and one bearing and went back together.
If you ever have dealings with a 24/7 workshop operation, you find nonsense like this happens fairly regularly. Getting quality handovers from one crew to the next is essential.
That is why I always put the bolts and parts back in the holes where they came from even if it takes extra time to screw them in, then out again mid-assembly - it takes less time than figuring out how you messed it up. Especially these days when it takes weeks to get simple parts, you completely forget how it came apart.
I do that also, one other thing I do is take the drain plug out and always put it on my toolbox, not on a frame member or the floor, and never put it back in until I am going to refill. I am either going to spot a puddle of oil or a mystery drain plug ....
Didn't you mention in an earlier post that the torque converter or it's components was discontinued by Cat? Cat is discontinuing parts on a 2017?
No new or exchange converters available.