PTO Question

Sat Jul 05, 2014 9:10 pm

Is the PTO shifter rod guide the only thing holding the PTO in gear?

My PTO won't stay in gear.
If put a screw driver through the fill hole and hold the PTO clutch in place I can't move the PTO pulley. As soon as I let the PTO clutch go and move the pulley, the clutch and shifter rod move and I can turn the pulley (feeling it bump/grind).
It appears the PTO shifter rod guide has enough wear in it that it allows the shifter rod to move forward just enough (<1/16") to allow the PTO to not fully engage.
There doesn't seem to be a wear issue with the pin as when the clutch moves the rod moves with it. There seems to be little slop in the pin and clutch grove, so I don't THINK that is the problem.

However, I can't move the rod guide back any further to hold the PTO in gear.

Where is the issue???

Re: PTO Question

Sun Jul 06, 2014 11:41 am

most likley the splines on the input shaft are rounded of along with the shifter pin being worn. when everything is correct it doesnt take much for the lever to hold the PTO in gear

Re: PTO Question

Mon Jul 07, 2014 2:09 am

Just a guess ... does your PTO shifter lever look bent at all? HOWEVER ... I bent one once when I didn't need to. My problem ended up being the little nub that moves the clutch was worn down to almost nothing. Like you said above, you THINK that's not your problem. The PTO system is very simple, take out the PTO shaft, have a look, and you will likely find the problem.

Re: PTO Question

Mon Jul 07, 2014 7:10 am

Thanks guy's.
The plan is to pull the PTO out this week. I hope it isn't the input shaft as that appears to be a far more complicated repair.
What is there to replacing the input shaft?

Re: PTO Question

Mon Jul 07, 2014 12:44 pm

IF it is the main shaft, you'll need to split the tractor at the back of the bell housing/front of the transmission. With the tractor split its pretty straightforward, the method is outlined in a maintenance manual. I'm sure someone can point you to it.

Re: PTO Question

Mon Jul 07, 2014 8:05 pm

Well considering it was warm, but not horribly humid, I pulled the PTO off and there is a partially sheared off lump on the end of the PTO lever that used to be the pin so that mystery is solved.
Now the question is, based on the pix attached should I also plan to replace the input shaft?
You do not have the required permissions to view the files attached to this post.

Re: PTO Question

Tue Jul 08, 2014 9:31 am

Sounds like your problem was the same as mine. Replace the shaft? Nope.

Re: PTO Question

Tue Jul 08, 2014 12:43 pm

Thanks.
I do think there is another issue though. There is at least a 3/8" to 1/2" gap between the PTO shaft and the input shaft. If I don't address it the clutch pin will eventually shear off again. From the reading I've done its either the PTO shaft has shifted back, or the input shaft has shifted foward. I have '47 so the PTO shaft bearing should be staked on. Im betting it was staked incorrectly or moved. As long as i have the PTO out, might as well check that bearing.

Re: PTO Question

Tue Jul 08, 2014 6:00 pm

Tore the PTO shaft down and its the earlier type where the bearing has to be staked in place.
I'm not messing with that so I'm just going to purchase a new one from TM.
Now, I reached inside and grabbed a hold of the input shaft with a big long needle nose and it barley moves when I push and pull on it (just wiggles a bit....very little).
So I'm wondering where the space between the PTO shaft and input shaft is coming from.
Does anyone have a measurement for the amount of input shaft that should be sticking out of the gear case into the PTO case?

Re: PTO Question

Tue Jul 08, 2014 7:50 pm

http://www.farmallcub.com/phpBB2/viewtopic.php?f=1&t=83732&sid=7cd68d3ded19ef8608a13ad992a539b7

Re: PTO Question

Wed Jul 09, 2014 7:16 am

Thanks Dell,

Still wondering where the gap is coming from.
If anyone can tell me what that gap should be, or better yet how far into the PTO case the input shaft should extend I would really appreciate it!

Thanks for all the help!!!

Re: PTO Question

Wed Jul 09, 2014 7:46 am

Is the bearing on the PTO shaft you took out sitting tight against the shoulder?

Sorry, don't know the measurements. There is no adjustment so never thought to measure. If it's wrong the most likely causes are the PTO bearing is in the wrong spot or the front transmission drive shaft bearing retainer is in wrong.

Is the depth of the pilot bushing hole greater than the pilot shaft length on the PTO shaft? Maybe somebody left part of an old bushing in there? I don't see how the PTO would tighten that away but doesn't take long to check with it apart.

Re: PTO Question

Wed Jul 09, 2014 11:16 am

The bearing seemed to be staked in correctly, but I'm replacing the whole thing anyway so I can use a clip instead of staking. I did notice the shaft could move about an 1/8" when inside the carrier. Found that out by tapping one end or the other of the PTO shaft on the workbench. Not sure where that movement is coming from as the bearing seemed solid.
I've already checked to see how far the pilot goes into the input shaft. The PTO shaft stops with about a 1/8" gap between the PTO shaft and the input shaft and whatever stopped it (I assumed it to be the end of the input shaft) is solid.
My concern is I'm spending some serious money to replace pretty much the entire PTO assembly (much of it was worn) and I don't want to wind up breaking the pin again because the shafts are too far apart.
Let me ask you this. How far should the PTO clutch slide onto the input shaft?

Re: PTO Question

Wed Jul 09, 2014 10:23 pm

vwfish wrote:......... The PTO shaft stops with about a 1/8" gap between the PTO shaft and the input shaft and whatever stopped it (I assumed it to be the end of the input shaft) is solid. .........
I can't say that I ever actually checked but it seems to me the hole in the end of the driveshaft is deeper than the pilot shaft on the PTO shaft is long, so the pilot shaft won't bottom out.

If you have a bushing measure it's length compared to the pilot shaft. (I replaced the bushing a year ago and seem to recall the bearing OD was 7/16" the ID was 3/8" and it was 3/4" long )

vwfish wrote:........ How far should the PTO clutch slide onto the input shaft?
Don't know an exact measurement but it is very little like in the 3/8" range (guesstimate).

Re: PTO Question

Thu Jul 10, 2014 7:13 am

Thanks Scrivet, that info will help and I much appreciate your feedback.
I'll take some measurements when the new parts get here.