frozen pto linkage

[jinman]

Jim,

I get your point. Items 21 and 22 are for the mid pto but item 26 fork, 25 rod works with Sliding gear A that is for TC35D and Tc40D which are parts of Lower, Rear Transmission PTO drive. Shaft 13 is clearly final pto shaft that can be covered externally with item 19 cap. This is totally independent of transmission. What am I missing there?

JC,

JC, I'm at work now and I need my repair manual which describes the functions of the parts a little better than I can do with IPC diagrams. What I mean by independent of the transmission, is that the pto will operate normally with the transmission in neutral and the clutch depressed or released. Nothing in the drivetrain through the transmission to the rear wheels effects the PTO. It is located in the same casing, but that is the only relationship to the gear or HST transmission. On the HST model, there is a shaft that goes through the HST case, but it is solid and not geared to the HST in any way.

EDIT: ...not geared to the HST in anyway. Not really a true. Sheesh! It is geared to the HST pump, but turns at engine speed and passes through the transmission to provide drive the PTO. Clear as mud, huh?

 

[BOOMHAUER]

jinman & JC,thanks for help, this forum is great. I will clean the area thoroughly around the valve, and then work on it. Do I need to do anything special before I remove the valve? I'd like to unbolt the whole valve and take it apart, inspect and lube it. Is this possible? NH lists a seal kit for the valve.

 

[Agent Blue]

My old TC 45 DA did the same thing. It happen after I rented a harley hake and made a few passes across the field. The dealer said it was quite common and mentioned something about a seal / o ring binding in the housing. I told the sales person about it but he said it was no big deal. I traded it on a 55 so they fixed it before the resale. It was just one more item on the aggrivation list for that machine.

 

[jinman]

jinman & JC,thanks for help, this forum is great. I will clean the area thoroughly around the valve, and then work on it. Do I need to do anything special before I remove the valve? I'd like to unbolt the whole valve and take it apart, inspect and lube it. Is this possible? NH lists a seal kit for the valve.

I'll post some more info in the morning, but you should carefully consider not removing the whole valve body if you can get by without doing that. The valve has two tubes that go down into the transmission case to the PTO clutch. Removing and installing this valve requires replacing o-rings on those tubes. Your IPC diagram does not show the tubes because they are not part of the valve, but they are there.

Second, you should probably not remove the valve spool unless you are ready to do seal replacement and you have a very cold freezer on your refrigerator. The Repair Manual says the spool has to be chilled before reinstalling to prevent damage because of the close machined tolerances in the valve body. My guess is that your valve may be galled internally and binding. If you can't get it loose by working and lubing, I would suggest you talk to your dealer's service department before disassembly.

I would not rely on a guy like me who has a manual and a lot of book knowledge, but no practical experience. You don't want to make the situation worse because of galling or a leak. I think this job would be relatively simple for someone with experience and not too expensive, but I would caution you to approach it carefully if you do it yourself. You seem like a really capable person, but you need to know there is some risk.

I'll post more diagrams in the morning.

 

[JC-jetro]

JC, I'm at work now and I need my repair manual which describes the functions of the parts a little better than I can do with IPC diagrams. What I mean by independent of the transmission, is that the pto will operate normally with the transmission in neutral and the clutch depressed or released. Nothing in the drivetrain through the transmission to the rear wheels effects the PTO. It is located in the same casing, but that is the only relationship to the gear or HST transmission. On the HST model, there is a shaft that goes through the HST case, but it is solid and not geared to the HST in any way.

EDIT: ...not geared to the HST in anyway. Not really a true. Sheesh! It is geared to the HST pump, but turns at engine speed and passes through the transmission to provide drive the PTO. Clear as mud, huh?

Jim,
I got all of that, I call it more murky

What got me baffled is the diagram in the CNH website. On TC40d they clearly show independent hyd clutch pack that turns a "PTO counter shaft and not a "PTO shaft. They show the final pto shaft in the rear transmission PTO shaft diagram. This final shaft is coupled to the counter shaft by the action of fork, sliding gear. It does not show the counter shaft (from hyd clutch) existing the back of the tractor. I see the pto lever actuates the pto valve spool but is there any other coupler passed the pto clutch? I'm thinking maybe in case of "independent pto" the counter shaft is directly and always coupled to PTO final shaft and in case of "live PTO" the final pto shaft is coupled to counter by a sliding gear. Looking forward to see what you'll find out after you look at you info at home tonight. Got to hit the sack.

Good night,
JC,

Boom Hauer, I fully concur with Jim about attempting to take the spool apart. That's risky at best right now, hate to dork it up prematurely as tolerances are very tight. That would be my absolute last resort and after I exhaust all my other options.

 

[jinman]

Well, here are the diagrams I promised. I think we are going to see a lot of "lights" coming on when you look at these diagrams.

The first diagrams (pto00, pto01are the details of the pto hydraulic valve and how it fits on the transmission case and attaches by two tubes to the pto clutch. The illustration at the bottom page pto00 shows the tubes with the valve turned upside down. The tubes have an oring seal at both ends and my stay in the transmission when the valve is removed or come out with the valve.

The second set of three illustrations shows the pto power flow through the transmission. The first one, pto03, is the 12x12 shuttle transmission without a mid-pto. You can see how the gear behind the clutch couples the output to the final shaft. The next drawing is the HST transmission with a mid-pto, but with normal rear pto engaged. The final illustration is the power flow to the mid-pto on the HST transmission.

All these illustrations show clearly that there is no mechanical engagement or sliding gears on countershafts except with the mid-pto option.

Boomhauer, I hope these drawings help you make the best decisions.

JC, I think you will probably understand now that these ptos are quite different from those in the past. These diagrams show how everything works together and are a whole lot better for description than the IPC.

 

[BOOMHAUER]

Sigh, I hate digging into something and making it worse. I know when to throw up the white flag. I will call a local tractor repair guy. He is a good friend of the family. Maybe he can save me a trip to the dealer. I will keep you guys posted on what exactly the problem is. Thanks again.

 

[JC-jetro]

JC, I think you will probably understand now that these ptos are quite different from those in the past. These diagrams show how everything works together and are a whole lot better for description than the IPC.

Jim... You da man!! great pics and explanation, even I could understand They sure are much better than IPC. Now I've got the following questions.

1) on 12x12 tranny, they don't mention shifter fork and coupler so pto is engaged on/off by hyd pressure/flow only. Engine off and pto shaft can not be rotated by hand is that right?

2) on 12x12 they show mid pto, I take it that is engaged by a lever out side of the tractor, is that right?

3)On HST they show coupler/sliding gear as if mechanically the PTO can be disengaged, is that right?

4) On HST , why do they show two mid ptos at two different location? why would they call it "optimal mid pto"?
5) it seems PTO clutch pack replacement requires separation of rear diff housing and transmission and pto access panel is for inspection and working on the pto spool valve only, is that right.

6) is the operation of shifter fork done by a lever outside of the tractor or done hydraulically inside ?. see no evidence of of moving the fork internally.


Thanks,
JC,


ps. Boomhaumer, I hope I'm not hijacking your thread, this is all gooood information. After all of this I wondered if somehow You got oil trapped by in your spool mechanism, on the first picture Jim had shows a capped outlet much like a relief mechanism, I just wondered if you open the relief valve, put a rag on it , weight it down and try to engage the pto, that should cause the hyd flow to spew out of the relief and may be just enough to expel what is plugging the flow? Jim, is there any chance with that? That could be done without damaging the spool and does not need much tearing into guts of this thing.


Boom

 

[jinman]

JC, rather than doing a long quote, I'll try to answer your questions by number.

1. Yes, the PTO cannot be rotated when the engine is off and the PTO brake sets. That's the function of the brake. And yes, there is no lever if there is no mid-pto.

2. There is no mid-pto shown on the 1st, 12x12 transmission diagram. Mid-pto is only shown on the HST diagrams. Perhaps you are confusing the mid-pto shaft with the FWD countershaft off the lower part of the transmission. That is a mechanical engagement. In the illustrations, it looks very much like a secondary mid-PTO shaft, but it is coupled to the FWD driveshaft.

3. I believe when the mid-pto is engaged on tractors with that option, that the rear PTO shaft is free to spin. Not sure...but I don't believe both PTOs can be powered at the same time.

4. I believe that "optimal" is a typo. They meant "optional" and were referring to the one PTO. Again, I think the "other" one is the FWD countershaft you are seeing.

5. Not sure whether it requires splitting or not. There have been several issues with some tractor models and PTO clutch/brakes. I do believe those tractors required splitting at the transmission case for repair.

6. There is a mechanical shifter fork for the mid-pto when installed. Only the main clutch is engaged by hydraulic pressure.

Finally, on your comment to Boomhauer: The capped outlet is indeed a relief. On the TC40, that relief is set to 260 psi. It controls how much pressure is on the PTO clutch before slippage. On a TC35, that pressure is set to 225 psi, I believe. I know it is quite a bit less. The chance of a hydaulic lock causing a problem in this area is pretty slim. If so, the PTO would not release. I think it is far more likely that the spool valve is galled or perhaps a piece of metal may have become lodged between the valve and the valve body. The problem will probably be as quickly fixed as it appeared if the trash or interference could be convinced to make its way back to the reservoir. If it is galling, that is much less likely to be easily fixed. From what Agent Blue said, his dealer did not think it was a serious problem and was pretty common. This is the first time I have heard of one binding up and staying that way on TBN.

 

[JC-jetro]

JC, rather than doing a long quote, I'll try to answer your questions by number.

Jim,

Much thanks for a thorough response. All clear now!! I think you are right, what appeared to me as a mid pto was indeed the front wheel drive shaft mechanism. I should have known better Although, not 100% sure but think sliding gear operation enables either front or rear pto and not both at the same time.

Thanks
JC,