Shear pin misery... only thing left is adding a slip clutch?

[Dadnatron]

This is the cheap one you had shipped from China right? Part of the reason it was so cheap was that it shipped with a cheap PTO shaft.....

There is no doubt... which is why I'm not bitching... just searching. I knew there was a likelihood that there would be kinks. The question I had to ask beforehand was 'Am I willing to deal with them for the $ savings.'

I am willing, and even if I have to purchase the brand name PTO shaft, it will still be significantly less expensive than an Italian import, for me. I can buy a new gear box, bearings, hydraulic cylinders, and shaft for less than the Italian machine. I might have ended up wasting my money, but I don't think so. The quality looks pretty good. The weak spots are the PTO shaft (obviously) and the gear box which is on the small side.

I like to try things... I'm not afraid to fail should something go bad. I've never imported anything myself, before, and it wasn't that bad at all. It wasn't just the $... it was saving the $ while doing something new.

 

[N80]

I've never heard of a PTO engagement working that way, but that's not to say that it doesn't. For the life of me I can't imagine why a tractor would go through that sort of routine to engage a piece of equipment. Maybe some sort of idiot proofing.

But for goodness sake don't go wasting $1000 when you probably do not have a problem. If your tractor will let you engage at low RPM then just do it and enjoy your mower and the savings that went along with it. If it continues to break pins after that then do what you have to do.

My tractor is only 45 hp. It has a lever that electronically engages the PTO but you can do it incrementally. Even at idle speed if I just throw that lever my 6' rotary cutter will hop and shake all over the place. I cannot imagine dumping the PTO at anything above idle. Something would give.

 

[airbiscuit]

Guys guys... I can engage at a lower RPM. I see your point.

I did a very slow PTO engagement, and it worked, but it felt like I was going to break that pin the entire time. I just didn't have confidence that it would hold. After it began spinning, there wasn't an issue, but still in my head, I knew the shaft is undersized.

You seem hesitant to accept engaging the PTO at idle. Why not keep engaging PTO at idle, and if no more broken shear pins = problem solved. If after doing that multiple times and you keep breaking shear, then maybe you want to look into Plan B.

 

[rustyshakelford]

Guys guys... I can engage at a lower RPM. I see your point. All I am saying is that according to the JD manual that comes with the machine, it says to throttle to PTO speed, then engage. I have an electric PTO clutch, and as soon as I engage it, the RPMs drop down. I don't think it is simply overcoming inertia via brute force (but I could be wrong). I think the tractor immediately throttles back then builds up. It happens when I have nothing on the shaft as well. I've just been doing what I grew up with and have always done and the manual corroborated my actions.

I did a very slow PTO engagement, and it worked, but it felt like I was going to break that pin the entire time. I just didn't have confidence that it would hold. After it began spinning, there wasn't an issue, but still in my head, I knew the shaft is undersized.

But... I am having a VERY hard time finding a long enough shaft to work. I did find one with a CV jnt and slip clutch... for $1070 + shipping. Probably $1200 to my door.... That's more than 50% of what I paid for the whole thing shipped to Cincinnati.

We have the same tractor. If you don't believe me, call your dealer and talk to the service department for the correct way to engage pto. Flat out, 100%, you are doing it WRONG. The manual doesn't say to do that, you are inferring it due to the way it's worded. If you can't engage at idle due to it killing the tractor, run the rpms up a little and then engage it. The tractor is dragging down because it's taking serious power to get things moving and what your doing is destroying your pto clutch. I've run equipment since I was 8 and most has been Deere. Nothing has every been engaged at full rpm.

Like I said, please call ANY dealership and they will tell you the correct way to engage pto

Brett

 

[Dadnatron]

No, No.... I'm not hesitant to improve. I'm not going to argue the merits of idle PTO starts. It makes sense that this would take strain off the system. And certainly I was able to get the machine working from a slow start.

Perhaps, as you say, I just need to try it a while and see how it goes. If all I need is an idle PTO start to get this running, certainly, I'd rather do that than unnecessarily add to the cost.

I think I will give it a shot and try. If it still doesn't work then I will go the new shaft route.

 

[k0ua]

The thing of it is, we all just assumed that everyone knew to engage the PTO at or just above idle to lesson shock loads on equipment.

So much for assuming. . This is a practical lesson of what happens when an irresistible force meets an immovable object. Or pretty close to that. Something is going to break. There is a heck of a lot of power in that PTO shaft built up at PTO speed, but there is a heck of a lot of mass in the implement to get rolling instantaneously too. Is the PTO shaft and shear bolt too small? Yep sounds like it, but if you can do a soft start and get by with it, why not use it and enjoy the savings?

And it has been a lesson for me too. Never assume anything. I will shut up now.

 

[mapper]

I think replacing the pto shaft with a larger one and continuing to engage it at full RPM may very likely destroy the gear box on the mower. Which you have pointed out several times looks fairly light weight. The shear pin is going to look like a very inexpensive and quick part to replace if you grenade the gearbox!

 

[IslandTractor]

I think I will give it a shot and try. If it still doesn't work then I will go the new shaft route.

Please don't go the new shaft route!! Listen to the unanimous chorus of your TBN guardian angels! Just learn to start the PTO at or more likely a few hundred RPM above idle. You'll soon learn what the lowest engine setting allows you to start reliably without stalling. Shaking a bit is par for the course.

 

[CCWKen]

I'd be more concerned about the tractor's PTO guts. The other end of most PTO shafts have fine splines and nothing like the drive splines on the outside. The diameter is usually smaller too. Like I mentioned earlier, the OP should keep tractor parts in stock to change out the rear end.

 

[N80]

Listen to the unanimous chorus of your TBN guardian angels!

Yep. Most of what I've learned about 'tractoring' I learned from the collective wisdom here at TBN. No shame in that. The rest I learned by trial and error. The error parts can be expensive and dangerous.

The OP did the right thing by coming here and asking. If the advice works, great! If not, nothing lost really.

 

[ruffdog]

The location of the pto clutch makes it a bit hard to repair and that is the reason we treat it with care.

 

[JRobyn]

Dad, I believe that your instincts that the manufacturer supplied the WRONG shaft are absolutely correct. Gentle starting at idle may work sufficiently to keep things going in the short term, but if I were in your shoes, I would be aggressively pursuing a heavier replacement (correct) shaft from the manufacturer. As a warranty replacement on their nickle. Even if does come by slow boat!

 

[PILOON]

Being an import the shear bolt is for sure metric.
Be sure you have the correct fit and again I would suggest a grade 5 or even a bit higher.
Graded will shear clean while soft will stretch and fail all too easily.
Added to what all has been said engagement at low RPM's will lessen the shock loading.

 

[mapper]

I might add that I not only start implements turning at an idle I also let the clutch out slow, there is a lot of mass that has to get moving back there.
Side note, my operators manual very clearly states that you always engage the pto at an idle!

 

[kthompson]

Not knowing the tractor you have, how does the pto engage? Do you engage it manually with foot clutch or hand control lever or is it electrical engagement where it engages in a shock fashion. IF you engage it manually, can you not rev the tractor up to rpm speed and slowly engage manually so there is no shock to the system. The other quesion is your tractor does not have a 1,000 rpm and the cutter is 540 do you? The pto shafts should prevent you this happening due to difference in groves.

I am with others here who say never engage at full pto rpm.

 

[rustyshakelford]

I might add that I not only start implements turning at an idle I also let the clutch out slow, there is a lot of mass that has to get moving back there.
Side note, my operators manual very clearly states that you always engage the pto at an idle!

Not knowing the tractor you have, how does the pto engage? Do you engage it manually with foot clutch or hand control lever or is it electrical engagement where it engages in a shock fashion. IF you engage it manually, can you not rev the tractor up to rpm speed and slowly engage manually so there is no shock to the system. The other quesion is your tractor does not have a 1,000 rpm and the cutter is 540 do you? The pto shafts should prevent you this happening due to difference in groves.

I am with others here who say never engage at full pto rpm.

He's running a 5100e Deere. It's a knob you pull up so no feathering to engage the pto. Have to rely in the pto clutch. They are 540/540ePTO so no 1000 confusion

I think he's got great info and hopefully will be problem free

Brett

 

[CincyFlyer]

Have you checked the gearbox for overfilling? You can build up some serious pressure when it's spinning up that you won't notice turning it by hand.

 

[Texasmark]

Being an import the shear bolt is for sure metric.
Be sure you have the correct fit and again I would suggest a grade 5 or even a bit higher.
Graded will shear clean while soft will stretch and fail all too easily.
Added to what all has been said engagement at low RPM's will lessen the shock loading.

My experience is that the higher grade is brittle and snaps whereby the non graded (grade 2) can survive a whack with slight distortion, aka cutting partially through the bolt allowing for several moderate whacks before breaking. Other thing I noticed was that it was easier to find a lower grade remnants in the shaft since it does smear and leave some material visible beyond the hole to help in locating.

Also my experience has been to use a locking nut and not to run it all the way down. Leaving some slop seems to help in bolt shank integrity.

10-4 on the idle start up and slow rpm advancement.

To each his own. We work through our tasks with what works for us under our sets of conditions. What works for me may not work for you and vise versa.

 

[Farmer495]

I think it's a combination of tractor engagement versus RPM

Have a 4x4 NH round baler, it uses a TINY approx 5/16" shear pin. Running it on 42 PTO HP tractor, engage at idle with IPTO (hyd lever feathering) no way could I start the baler turning with a bale in the chamber without the shear pin breaking. Run it now on a 64 PTO HP tractor,engage at idle with IPTO and hyd lever feathering, I can easily start the baler turning with a full bale...never break a shear pin. Same operator, same baler, same tiny shear pin, different tractor with SAME PTO engagement style.

I NEVER engage PTO at anything above idle/slightly over idle, and this in in real world in a farming environment trying to beat weather. Broken equipment makes no hay.