John C.
Senior Member
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.
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.