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Hi Everybody,

I was on my trusty old 8N with a Woods RM59 finishing mower (attached to a slip clutch) and hit an obstruction. The mower stopped spinning and the PTO is free but will not engage when I push the shift lever. What is the most likely thing that has happened?

The PTO shaft spins freely and the hydraulics (lift) appears to work as usual when I engage the PTO lever. No problem lifting the mower deck. It is just the PTO that will will not engage.

Will I have break the tractor open to find the problem?

Thanks,

Mike
 

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Sounds like you had some fun and probably a few select words over this tractor lately. Let's see if I can help. Good to see you using an ORC for your mower (even though the finish mowers are usually pretty mild) Let's hope for the best and plan for the worse.

Basically, your problem is a PTO problem. Just for future reference, the pump drives off the PTO shaft and if the PTO shaft isn't turning, neither is the pump. The PTO shift mechanism is usually very rugged and does not fail. It consists of a sliding collar with an internal spline which slides back and forth on the splines on the front end of the PTO shaft, and engages or disengages with a splined hub attached the rear end of the trasnmission layshaft. The sleeve is slid back and forth by a shift rail which is driven back and forth by the PTO shifter lever in the LH inspection plate. It appears that it might be a yoke engagement problem as well, but probably more to do with the sliding collar and pin. You should be just fine! :D

Let's get started!

First, remove the inspection plate with the PTO shifter, it all comes off together. The shift lever is pinned to the shifter fork where it goes through the plate. If this pin is sheared, you can shift till Kingdom come and nothing will happen. (hopefully this will be the easy fix part!)

Behind the plate, you'll see the shifter rail, and you'll see the notch in the rail where the shifter fork rides. It's not unknown for the end of the shift fork to pop out of the notch. You should be able to slide the rail back and forth with your hands. Forward = engage, backwards = disengage. If it slides but does not shift, then most likely the shifter dog on the forward end of the shift rail has fallen off. To locate and repair this, the quickest access is by removing the PTO and hydraulic pump. (4 bolts on the rear for the PTO shaft --- getya a new gasket and possible PTO seal and get ready to clean it out good if you hadn't done so in a while --- it is a really nice big mess in there!) For the H pump, you will need to drop the whole unit from below the tractor, grab some gaskets and a pressure relief valve while you are at it! (Call us Don B. fron www.just8ns.com and tell em Andy from Tractorforum.com sent ya if you need any parts!)

I suppose that it is theoretically possible that the driving collar on the end of the transmission layshaft has come loose, but I have never known this to happen. And, in any case, it is keyed to the shaft and even if it were loose, it would still drive. If this is the case, access is also by removing the hydraulic pump. Sounds like you should have an easy fix in the works, my friend. :D

Well, I hope this gets you started. If the tractor is still moving and driving, you probably just need a little PTO check. Hopefully you will be lucky. Take lots of pics and let me know if you have any more questions or need any help.

Regards,
Andy
:tractorsm
 

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Mike, you state the lift is still working. If this is so you either blew out your over running clutch or broke the pto shaft on the back side of your pump, probably where it exits the rear housing.

I would bet the internals of the ORC (over running clutch) have come apart. Disconnect the mower and see if it is very loose now.

Hope that helps
 

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so have you checked this Mike? Let us know what you find.
 

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Discussion Starter #5
PS Hit it on the head. I snapped the PTO shaft right before the bearing as it exits the rear end of the tractor. I'm going to replace it with the 1 3/8 " shaft rather then the 1 1/8". I wonder if the turning angle of the mower shaft put a little too much pressure at that point.

Mike
 

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make sure the pto shaft from the tractor to the implement is "short" enough to allow for full movement of the implement through the entire range of the lift.

Make sense? Probably not lol.

The lift arms on an 8n are short. Every pto driven implement I have bought has needed the input shaft shortened. If you dont shorten them or not enough the slip shaft will bind and the weak link is the PTO shaft of the tractor.

It should be a very easy fix. Good luck.
 

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Good call, PSRumors...... glad you found the issue out, Mike.
Keep us posted with info and pics!

Good news!

:lmao:
 
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