Could I damage the PTO by doing this?

Big Trees

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Aug 28, 2015
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Hello guys. I was wondering if I could damage the internals of the PTO or tractor somehow by bush hogging stuff that has thick stalks? I use my B6000E to clear the brush on parts of our wooded property and it has done a wonderful job and impresses me quite often on how much of a work horse the little thing is.

The base of most of the stalks are about 1" thick but there are some that I have hit and cut that are close to 2" thick at the base. I try to go through a time or two with the bush hog raised up some and lower it down a little more each time so I'm not whacking it all down at once. But there have been times when I went lower than I probably should have and the tractor would bog down a bit and I raise the bush hog and everything sounds normal again.


My question is, am I damaging the internals by doing this?

I'm picturing the gears (or whatever) inside of the tractor/pto connection banging up against each other when I'm hitting the thicker stuff and the tractor is bogging down.

Am I correct or am I over thinking things?

I don't want to damage the tractor but I need it to clear brush.


Thank you all in advance. You guys are always a big help.
 

rbargeron

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Woody brush is more flexible than rocks so the impact is less severe and breakage less likely. That said, the lower you try to cut it the more you flirt with damage. Rotary cutters have swing-back blades so impact to the tractor gears is reduced. (Installing a slip clutch on the pto shaft helps too). Meshing gears contact each other along 2 or three teeth as they turn. They'll withstand quite high loads, but have their limits.

Generally if there are no rocks the tractor will bog down and quit before something breaks. Any rocks, all bets are off. Take care, Dick B
 
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Big Trees

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Woody brush is more flexible than rocks so the impact is less severe and breakage less likely. That said, the lower you try to cut it the more you flirt with damage. Rotary cutters have swing-back blades so impact to the tractor gears is reduced. (Installing a slip clutch on the pto shaft helps too). Meshing gears contact each other along 2 or three teeth as they turn. They'll withstand quite high loads, but have their limits.

Generally if there are no rocks the tractor will bog down and quit before something breaks. Any rocks, all bets are off. Take care, Dick B
Thank you very much for the reply and the explanation. It makes perfect sense. I will look into a slip clutch. I have heard of them but don't think there's one on this machine. I really appreciate your help. You take care as well.
 

D2Cat

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Everything rbargeron stated is true, however, if you're going over material up to 2" dia. with a B6000 tractor....start putting extra savings in your cookie jar, because you'll be need it soon!

In my opinion you're in the mode for mechanical problems. Then start looking for parts for a B6000, and the fun begins!! What I am trying to say in a reasonably nice way...you are destroying your machine by using it in the process you asked about.
 

Big Trees

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Everything rbargeron stated is true, however, if you're going over material up to 2" dia. with a B6000 tractor....start putting extra savings in your cookie jar, because you'll be need it soon!

In my opinion you're in the mode for mechanical problems. Then start looking for parts for a B6000, and the fun begins!! What I am trying to say in a reasonably nice way...you are destroying your machine by using it in the process you asked about.


Thank you for the honest reply, D2Cat. That's why I asked and I hoped for honest answers. To be clear, most of the brush is an inch or less, the main part less than that inch. But there are some pieces that are bunched up in the mix that are close to or right at 2 inches. I need to clear the brush but I don't want to ruin the machine. I don't have a whole bunch of money tied up into it ($800 for tractor and bush hog) but I would hate if it broke on me.


Thank you guys for your help. I will be more careful what pieces I cut down with the bush hog from now on. I am grateful for this place and the helpful folks that keep it going.
 

Big Trees

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ONE OTHER QUESTION.


If I did damage something by doing this, would the transmission be damaged? Or just the pto? Therefore I would be able to use the machine with a back blade that doesn't require pto or no?


Thank you.
 

North Idaho Wolfman

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ONE OTHER QUESTION.


If I did damage something by doing this, would the transmission be damaged? Or just the pto? Therefore I would be able to use the machine with a back blade that doesn't require pto or no?


Thank you.
If it does just break the PTO, it will depend on where it breaks, it might disable the whole tractor. ;)
 

NWhomesteader

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Isn't this what shear pins or slip clutches are for? They shear or slip before damaging the drive train. That's the idea anyway.

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Big Trees

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Isn't this what shear pins or slip clutches are for? They shear or slip before damaging the drive train. That's the idea anyway.

Sent from my SCH-I545 using Tapatalk
I need to look into a slip clutch. I have a bolt that holds the pto shaft onto the tractor's pto hookup but I'm not sure if that's considered a shear bolt. I put a grade 5 bolt in there a week ago because the bolts I was putting in there either came unbolted or got sheared too quickly. I wasn't mowing the rough stuff then, just regular grass. Because I put grade 5 in is why I started wondering if maybe I did the wrong thing by doing that.
 

altonwelch

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Most likely if anything is hurt it would be the bush hog gear box or driveline. And if the blades are cutting the brush its not really that much shock, not like hitting a rock or the ground. But, like others have said, its not a good idea to cut that big of brush on a regular basis. Every once in a while it probably won't hurt much.
 

Jim L.

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Tractor Supply has packages of bolts which are rated for shear.

If you can't find these, then a lower grade steel will work.

Nuts going loose can be controlled with thread locker.

Traveling slow helps.

When engaging the pto, it helps to clutch in at a low engine rpm. Clutching in at a high engine rpm puts concentrated stress on the bolt which will make it fail faster.
 
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Big Trees

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Thanks to you both for those last two replies.

I will look for the pack of shear bolts or will get a less strength bolt. I had some but like I said something happened with one real fast and I didn't even bother with trying the other because of that reason. I will get some thread locker for the lost nut possibility. Thanks for the suggestion.

On a note about the tip concerning engaging the pto at slow speeds. Every time I use the clutch to do anything, whether it's switch gears or turn on/off the pto I ALWAYS come to a complete stop before doing so. I didn't know there was another way to do it.


Thanks guys.
 

Russell King

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The bolt you use at the rear of the PTO shaft should be long enough so the unthreaded shank goes through the entire PTO yoke. There may be a couple of threads left in the yoke but for sure unthreaded bolt shank goes through one side, through the driven mower shaft and into the other side of the PTO yoke.

There should be some C clip on the end of the driven mower shaft to keep the PTO shaft on the driven shaft when the shear bolt fails. If not you can end up with a loose end of the shaft trying to kill you!


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Big Trees

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Russell King- Thanks for the post. I need to look into that shear bolt with a C clip on it. I have not seen those yet. Still new to the tractor world lol. Thanks for the tip.



What Russell spoke about is my fear and problem. The bolt I have is only used to hold the shaft onto the PTO. If there is no bolt there then the shaft would come undone from the PTO and would start hitting everything. It happened many times before I put the grade 5 bolt in.


The PTO and shaft both have splines so the way I see it the bolt isn't doing anything to keep from any damage being done since the splines in the PTO and shaft are locked into one another. The way I see it the bolt is only there to hold the two parts together. Am I not understanding this correctly?


Here is two pictures of the setup. The bolt in pics is the "soft" bolt, it sheared not even 5 mins after trying it out again. I did not hit ANYTHING hard at all. It sheared just from the regular movement of the PTO. Something just isn't right with this.

Thanks

 

Buffalo

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There is supposed to be a c-shaped clamp that holds the shaft inside the U shaped piece at the
end of the arrow. If the shear bolt shears, the shaft is retained but allowed to free-wheel. DO NOT USE THIS THING AT ALL WITHOUT THAT CLAMP !!!! You are correct to think
that the drive line is deadly !!! If the clamp is not present, you can probably find one
at almost any farm supply, and it won't cost much at all. Allowing the drive line to pull off
while in motion is a really scary thought! Heck - I don't know what the thing is called, but
someone on here will probably tell you before I can post this.

Stay SAFE ! This is not one to fool with !
Heckfire --- email me now ! I'll send you my phone number and talk you through it. bw@w5gfe.org

I AM trying to scare you !
 

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Big Trees

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Aug 28, 2015
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Thanks for the post and the information, Buffalo! I will look for those C clamp bolts you are kind enough to inform me about. I sincerely appreciate you all's help!! I really do!

I won't use it again until I get those clamps. Thank you, sir.
 

Big Trees

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I'm having trouble finding a picture or link to one of the shear bolts with a clamp. Tractor supply doesn't show any and I can't find any other place with some. If anybody has a picture of you can you please post it or post a link to one? I'd really appreciate it.