580B Rockford PowerShuttle - Stumped and missing Phil!

[Axl]

First, I will have to say this is a great forum. I have been a heavy equipment mechanic for about 26 years now and I find a lot of good information here for even the advanced mechanic. Now, I am looking for some help on an older 580B with a Rockford power shuttle that has me totally beating my head on the wall! :Banghead A friend of mine brought me this machine he purchased with a the forward and reverse clutches burned up. We split the machine in half and replaced all the bearings, seals, and anything that looked questionable from the torque convertor to the manual transmission. When assembling the clutch packs, all were bench tested with 150psi air pressure. I had to replace all the springs in the clutch packs. This took some research. I did find some that have the exact number of coils other than the diameter of the spring was a little heavier. They worked great and I did not have to cut them down. I think the price for both sides was around $50. If anyone is interested I could dig my receipt out and tell you where I got them. The trouble I am having is that both clutch packs want to engage at the same time. The pressures on the convertor, lube port, and clutch pressure port fall within spec. The case was bored and sleeved where the cast rings from the main shaft normally show wear. I removed the control valve assembly and dye penetrate checked for cracks. Nothing showed up. I tested the clutch packs through the top plate ports on the shuttle valve and both operated normally. I got to wondering if I missed something on the shuttle valve assembly so I removed the trans/differential. The cast rings were still in new shape, nothing broken. Wondering if the rolled ports inside of the shaft could be leaking by I replaced the main shaft. After reassembling the machine nothing changed. Since there are no individual clutch ports or no test ports down stream on the spools I replaced the control valve assembly. No change. I am at my wits end! I have rebuilt the twin disc in another machine and found it very straight forward. If anyone has and idea of what I may have missed your reply would be most welcome. The trouble with these older machines at the dealer is most of the older mechanics have retired. The new younger guys do not have much if any experience with these machines. I have tried talking to the service manager at our Case dealer and he has very little experience trouble shooting this model. The best he can say is bring it in.

 

[d2r]

1973 case 580b - power shuttle q

sorry, i can't help with your problem, but i do have a question.

is there a way to tell, without splitting the tractor, whether i have a rockford or twin disc shuttle? is one better (reliability, parts availability, cost?) than the other... and can one be swapped out for the other?

perhaps we should also set up a thread for companies that sell replacement parts? as these machines get older, i'm guessing parts are just gonna disappear. having that info in one place would be helpful.

 

[ManicACMechanic]

As I am not an expert on shuttle trans, but am an expert on automatic transmissions, I will ask this question: You said you were able to test each individual clutch through port in the shuttle valve. Were you able to verify that both packs release fully when the pressure is taken off(assuming you used air pressure to test them)? I ask this because a pack that is pressure locked will seem to be engaged. Is one pack opened to drain when the other is engaged, or do they have constant bleed orifices. If the former, check for restriction in the drainback circuit. If the latter, check for plugged or covered bleed orifices. I know this will probably not help, but sometimes can help kickstart the brain.

 

[Axl]

Manic, I bench tested the clutch packs by blowing through the individual ports on the main shaft and also after installing in the case through the ports on the case. There is lube pressure going through the clutches at all times but not enough pressure to actuate the pistons. This vents the clutches when they are not being applied. Both clutches will actuate in neutral. The lube pressure is not out of spec. I have no way of measuring pressure down stream of the spools. It would be interesting to see what static pressure is in the port not being applied.

 

[Axl]

d2r, Phil has a post some where in the forum with a picture so you can see the difference. Everyone has said the Rockford is easier to rebuild. I suspect because there is no need to use a press to rebuild the clutches. I found the twin disk was very difficult. It is much like the Funk transmissions found in Caterpillar forklifts and some other equipment. The only thing I didn't like about the twin disk is the center plate which separates the forward and reverse clutch is held in place by a roll pin. It caused me some grief before I figured out that is was broken. That is too long a story for this answer.

 

[Axl]

I forgot to answer one of your questions. Yes, the Rockford and the Twin Disc can be swapped.

 

[Axl]

Manic, I reread your reply. Yes, the clutches are fully released when their is no pressure being applied whether hydraulic or air. I have the cover off where I can view the clutches directly.

 

[willie59]

Yes, the clutches are fully released when their is no pressure being applied whether hydraulic or air.

I'm not a 580B expert, but I'm curious, maybe just need clarification. If you have verified that the clutch packs test good when fitted in the machine, able to engage and release each clutch pack by using test pressure via a port, then seems to me the problem has to be in the shuttle control valve sending pressure to both packs at the same time when running. I don't know how, just seems like the problem has to be there.

 

[Axl]

Yes, I thought that could be the problem. I replaced the entire control valve with no change.

 

[willie59]

Ok, you're making my head spin in continuous rotation. :dizzy

You've tested each clutch pack with air pressure on the bench and tested via ports after assembly on the machine, and have reported each test proper. Yet both are under pressure when operating. Furthermore, each are under pressure after replacing entire control valve??? Boggles the mind indeed! Not trying to add to the perplexion (ok, a word that this event has created), but rather hope this question helps spur the mind of others here, you say both clutch packs are under pressure, just when does this happen? Upon start up? Or, do you start up, then engage either fwd or rev and then experience pressure to both clutch packs? Just trying to help because I'm clueless.

 

[Axl]

d2r, I found your picture that Phil posted. It is on the thread 580ck shuttle/converter

 

[ManicACMechanic]

If you are saying that both clutches are engaged in neutral, then I agree with willie59, it has to be in the valving. Even if something was wrong with the clutch packs, there shouldn't be enough pressure to apply them unless there is fluid bypassing a valve or gasket. It has to be upstream of the clutches.This may have been what burned up the clutch packs before you got to it. I guess look every place where high pressure passages are near low pressure passages, and look for a damaged gasket, slip ring, porosity in the case, or missing core plug or spool cap. That fluid has to get there somehow and you're looking for a fairly large diversion of fluid. Do you have a hydraulic diagram for this machine?

 

[Axl]

It takes a few seconds on start up to have the clutches apply. It is if the pressure from the lube oil is too great. This is not shown on the gauge testing the lube oil, but the test port is upstream of the spool. If i press on the declutch dumping the pressure both clutches are released and the process starts over. Shifting to forward or reverse makes no difference unless I press lightly dumping a small amount of pressure with the declutch. Testing above 1000rpms the results are amplified and the will result in smoking the clutches quickly. I had the cover off and only tried once when the smoke started rolling I backed off instantly. I rechecked all gasket numbers for the control valve. Although it seems that the CK was the one with different gaskets.

 

[Axl]

Yes, I have the original service manual. There are only two ports which go the shuttle valve. Lube oil (low pressure) is supplied to one or both of the clutch packs not being supplied by the clutch pressure (high pressure). I have used dye penetrate to check for cracks and have found none.

 

[willie59]

If i press on the declutch dumping the pressure both clutches are released and the process starts over.

I'm still perplexed. No matter if it takes a few seconds or a few minutes for pressure to apply (in neutral) to both clutch packs. That's the part that baffles me, neutral.

 

[Axl]

That's what I am struggling with.:beatsme I really like puzzles and had good luck in past with projects that were passed on to me by other mechanics. I was hoping someone else had a similar experience because this one is a toughy.

 

[mitch504]

I thought of the lube oil not being able to get out, but that would raise the pressure on the upstream guage, unless there was a check valve, or something acting as a check valve downstream of the guage. Can you stop the lube oil for a minute or two?

 

[mitch504]

It does sound like a gradual build up, rather than a sudden application. Leakage somehow from one pack to the other? You replaced the shaft, but leakage on the outside of the shaft from one pack to the other?

 

[ManicACMechanic]

Valve body fastener torque? Warped case? They may be applying through that declutch circuit. Now I'm really speculating, as I've never seen one of these. I hope you figure this out, and please let us all know what it is. I've got to hit the hay.

 

[ManicACMechanic]

Oh, one more thing, if this has a cascade valving system, make sure that the relief valve for the lube pressure isn't blocked. That could cause a build up of pressure way above proper lube pressure. I though of this because I would think that a fully engaged clutch would take a lot of power to slip and burn. Now, just partially engaged, it would have just enough hold to smoke itself.