Slip Clutch/Gear Box Spline Problem

[AgMan]

The bolt goes through the slip clutch hub and will only go through all the way if it is lined up with the concave groove on the gear box shaft. The groove on the shaft looks to be the diameter of the bolt. Just like your example you posted above except this is a 1000 rpm shaft rather than the 540. So I believe it's a mechanical key. (still learning these terms)
The part number, size and the grade of the bolt is listed above by TX Jim. That is the exact JD part number I have. Attached pic of bolt bag.

As far as torque, I'm just not sure but I will find out.
Thanks again. This is very frustrating and it has to be I'm missing something.

 

[SPYDERLK]

The bolt goes through the slip clutch hub and will only go through all the way if it is lined up with the concave groove on the gear box shaft. The groove on the shaft looks to be the diameter of the bolt. Just like your example you posted above except this is a 1000 rpm shaft rather than the 540. So I believe it's a mechanical key. (still learning these terms)
The part number, size and the grade of the bolt is listed above by TX Jim. That is the exact JD part number I have. Attached pic of bolt bag.
View attachment 438804
As far as torque, I'm just not sure but I will find out.
Thanks again. This is very frustrating and it has to be I'm missing something.

OK. ... The female spline just slips over the male and cannot escape because of the bolt in the shaft groove. This is identical to the connections I often see on the tractor PTO stub - the old push button style. The spring loaded pin operated by the button does the same thing as your bolt. TOTALLY trouble free in my experience, but on the tractor and on the 6 spline 540 pto stub. Your situation is worse in several ways:

,,,1] The coupling is on the implement and bushogs can jump around a lot, all impulse coming thru the gearbox,

,,,2] The slip clutch presents an overhung load on the coupled joint,

,,,3] The floating joint is free to move and wear,

,,,4] You have a fine spline [presumed the std 1-3/8 X 21 tooth used for 1000rpm?]

Altho the 1000 rpm is great for transmitting a lot of power the use of fine spline is unfortunate in that they cant put up with much wear and still work optimally. ... And your case of a floating [not clamped] fine spline supporting overhung loading in the face of some vicious vibration is all bad.
,,,If your MX10 is the same as others, and your use is typical, then why dont they all show what youre seeing?
:confused3: MAYBE that shaft is bent a little. ... also, from your bolt pic, the bolt wear is quite close to the threads and their small root is vulnerable to notch failure. A longer shank with just enuf thread to tighten the nut would be more durable. Also, using the largest bolt that will pass thru would be an improvement.

 

[SPYDERLK]

Just looked at the bolt pic. That wear is nothing like it should get acting in the hollow radius of a groove. I would expect impressions from spline points at most. It looks like its engaging the flat tops of the spline teeth.
larry

 

[banjodunn]

G'day check the crush slot in the slip clutch is wide enoughto allow the clutch to clamp up and not bottom out.


Jon

 

[Baby Grand]

Just looked at the bolt pic. That wear is nothing like it should get acting in the hollow radius of a groove. I would expect impressions from spline points at most. It looks like its engaging the flat tops of the spline teeth.
larry

^ My thoughts, exactly, Larry.
I had my doubts, thinking a coarse, 6 tooth spline can't make those closely spaced, narrow witness marks.
But that was before the OP mentioned that it's a fine pitch, 21 tooth spline.
Now the physical evidence appears to match that failure mode.

3 reasons that I can think of:
1) The spline is mis-assembled from the get-go. Easy to check - does the bolt slide into the scallop in the external slot without force?
2) Spline never gets adequately secured (as banjodunn suggests) because the slot is too small or the teeth are two worn or some combination of the two.
3) The spline is correctly assembled, but the two halves get forced out of axial alignment in operation. A little harder to check, but I suspect the PTO shaft is cut just a tad too long, so it binds when the shaft is trying to reach it's shortest length as the 3 point hitch is moved through its full range full motion.

Maybe try this:
With the implement unhitched, compress the PTO shaft until it bottoms out, now measure the length of the compressed shaft between two point that you mark with a grease pencil or Sharpie. The hitch it up to the tractor and take a few measurements through those marks at different 3ph heights - all the way down, medium height and all the way up. If the length gets close to the compressed length, measured with the implement off the tractor, I think that would convince me.
-Jim

 

[SPYDERLK]

Thanks to all who have repiied with ideas and suggestions. I just got in last night and have not been able to reply to your posts from my mobile device. All suggestions have been addressed and looked at. Correct bolt and nut being used (JD). New slip clutch was purchased because splines were wore. Splines on gear box shaft are in good shape. Tube is greased and movement is great. The tractor is now being looked at by a certified/independent JD mechanic. He is very puzzled and has opened, I think it is callled a D-TACK case with JD, where an engineer who is very familar with the MX10 will call him to discuss, reccomend suggestions or share if this has happened in the past.
All of your reccommendations have been addressed either before you suggested or yesterday when I was up at the site with the tractor. I will keep you posted the ultimate outcome.
Thanks

How does the bolt hold the male/female splines together?

,,, Does it clamp them or only act as a mechanical key to prevent them from sliding apart?

,,,,,, What is the size and grade of the bolt? What is the torque spec used?

The bolt goes through the slip clutch hub and will only go through all the way if it is lined up with the concave groove on the gear box shaft. The groove on the shaft looks to be the diameter of the bolt. Just like your example you posted above except this is a 1000 rpm shaft rather than the 540. So I believe it's a mechanical key. (still learning these terms)
The part number, size and the grade of the bolt is listed above by TX Jim. That is the exact JD part number I have. Attached pic of bolt bag.
View attachment 438804
As far as torque, I'm just not sure but I will find out.
Thanks again. This is very frustrating and it has to be I'm missing something.

OK. ... The female spline just slips over the male and cannot escape because of the bolt in the shaft groove. This is identical to the connections I often see on the tractor PTO stub - the old push button style. The spring loaded pin operated by the button does the same thing as your bolt. TOTALLY trouble free in my experience, but on the tractor and on the 6 spline 540 pto stub. Your situation is worse in several ways:

,,,1] The coupling is on the implement and bushogs can jump around a lot, all impulse coming thru the gearbox,

,,,2] The slip clutch presents an overhung load on the coupled joint,

,,,3] The floating joint is free to move and wear,

,,,4] You have a fine spline [presumed the std 1-3/8 X 21 tooth used for 1000rpm?]

Altho the 1000 rpm is great for transmitting a lot of power the use of fine spline is unfortunate in that they cant put up with much wear and still work optimally. ... And your case of a floating [not clamped] fine spline supporting overhung loading in the face of some vicious vibration is all bad.
,,,If your MX10 is the same as others, and your use is typical, then why dont they all show what youre seeing?
:confused3: MAYBE that shaft is bent a little. ... also, from your bolt pic, the bolt wear is quite close to the threads and their small root is vulnerable to notch failure. A longer shank with just enuf thread to tighten the nut would be more durable. Also, using the largest bolt that will pass thru would be an improvement.

^ My thoughts, exactly, Larry.
I had my doubts, thinking a coarse, 6 tooth spline can't make those closely spaced, narrow witness marks.
But that was before the OP mentioned that it's a fine pitch, 21 tooth spline.
Now the physical evidence appears to match that failure mode.

3 reasons that I can think of:
1) The spline is mis-assembled from the get-go. Easy to check - does the bolt slide into the scallop in the external slot without force?
2) Spline never gets adequately secured (as banjodunn suggests, below) because the slot is too small or the teeth are two worn or some combination of the two.
3) The spline is correctly assembled, but the two halves get forced out of axial alignment in operation. A little harder to check, but I suspect the PTO shaft is cut just a tad too long, so it binds when the shaft is trying to reach it's shortest length as the 3 point hitch is moved through its full range full motion.

Maybe try this:
With the implement unhitched, compress the PTO shaft until it bottoms out, now measure the length of the compressed shaft between two point that you mark with a grease pencil or Sharpie. The hitch it up to the tractor and take a few measurements through those marks at different 3ph heights - all the way down, medium height and all the way up. If the length gets close to the compressed length, measured with the implement off the tractor, I think that would convince me.
-Jim

... Good!

G'day check the crush slot in the slip clutch is wide enoughto allow the clutch to clamp up and not bottom out.


Jon

Maybe it is a clamp socket. Iv not been able to get a complete clear answer. OP evidently thinks we know exactly how the MX10 is built.

 

[Egon]

OMW45015: MX8 and MX10 Rotary Cutters table of contents
Might be of help??

Look at the length of the drive shaft off of the tractor?

 

[SPYDERLK]

... Maybe it is a clamp socket. Iv not been able to get a complete clear answer. OP evidently thinks we know exactly how the MX10 is built.

OMW45015: MX8 and MX10 Rotary Cutters table of contents
Might be of help??

Look at the length of the drive shaft off of the tractor?

Thanks Egon. I refuse to look these things up for things that are right there in front of the poster.
... From ref, It seems its not a floating joint or a typical squeeze clamp joint. Instead, it looks like a taper pin is called out to retain and immobilize that joint.

It had occurred to me that this might be it, but there are so many omissions and contradictions that I didnt want to throw shotgun guessing at it to further confuse the issue.

That bolt being used in place of the taper pin creates a floating joint -- ALL BAD at that location on a bushog. The collar has been replaced but, considering the fine spline, the shaft may be ruined.
larry

 

[Baby Grand]

So it's a tapered pin? Sheesh. Three shotgun blasts in a dark room and I still missed.
Other than the wedge bolts used on cultivators, I haven't seen anything like that since I took the shift linkage on a 1971 SAAB apart.

 

[SPYDERLK]

Regardless; plenty of good thinking.

,,,See Egons link and see what you think.