BrushHogging:

[tf116]

I've been having a problem with my brushhog for some time.....It keeps shearing bolts...I have a slip clutch which works and I can run over stumps,etc..and no problem....Can be out of grass and making a turn and it shears a 1/2" grade 8 bolt!......only seems to shear bolts on turns, have checked gear oil level (ok)shortened the pto shaft, already has new bolts and cutters on it....does anyone have any ideas at all ,as to what can be causing this?....
oh by the way, I have the stabilizers set,so its not swinging back and forth....
I would appreciate any info , bolts are about 1$ apiece plus nut..and after 30-40+ it gets expensive....not to mention having to replace the bolt itself....

thanks Mike

 

[Ford960]

Why a slip clutch and a shear bolt? Something is definately binding to shear a 1/2" grade 8 bolt. What mower and tractor is this?

 

[Farmwithjunk]

I've been having a problem with my brushhog for some time.....It keeps shearing bolts...I have a slip clutch which works and I can run over stumps,etc..and no problem....Can be out of grass and making a turn and it shears a 1/2" grade 8 bolt!......only seems to shear bolts on turns, have checked gear oil level (ok)shortened the pto shaft, already has new bolts and cutters on it....does anyone have any ideas at all ,as to what can be causing this?....
oh by the way, I have the stabilizers set,so its not swinging back and forth....
I would appreciate any info , bolts are about 1$ apiece plus nut..and after 30-40+ it gets expensive....not to mention having to replace the bolt itself....

thanks Mike

Shearing a 1/2" grade 8 bolt means you've got a major issue. Is there any way to get us a picture of the mower/tractor in "working configuration". Sounds like something binding, but what?

How big (wide) of a mower is it? What brand? Is the slip clutch able to slip?

By the way, saw on your personal bio where you're in to blacksmithing. I'm just starting to take up the cause myself. Up 'till now, I've just beat on metal. Starting to learn the correct way with correct tools. Any good sources for tools of the trade? (Got a pair of anvils, a home-made gas forge, and an assortment of hammers. From there, the sky's the limit)

 

[tf116]

Have a 6' Condor brushhog..with a Kioti DK55 tractor....have stabilizers locked in and slip clutch slips,
the reason for the slip clutch is I was pulling the hog with an 80+ HP MF and it would twist the pto shafts...seemed to work on MF, just bought another farm and been hogging it ... cleaning it up..got rid of MF and bought a Kioti....
every thing works great and as per designed, and then when make a right turn it shears the bolt......changed blades and bolts a year or so ago, got plenty of oil in gear box..and runs smooth after first startup.....stabilizers set ...its just a cheap hog,but does a beautiful job of cutting ....I'm stumped......Mike

 

[CDsdad]

Your stabilizers may be too tight, causing everything to get in a bind when you turn and not giving a little slack. I run mine with enough slack to allow the cutter to take the blow or shock if I hit something, and hopefully not the tractor, but not loose enought to rub tires or anything. I'd double check that slip clutch too. Shearing grade 8s regularly, that's tough.

 

[RonR]

Longshot, but is your PTO shaft maybe too long and bottoming out and shearing the bolts becuz of that????????????

ron

 

[tf116]

Will try hogging with stabilizers looser , also I cut about 4" off the pto shaft, still sheared bolts....Mike

 

[hsvhobbit]

Not real experienced with tractors yet but if you've got a working slip clutch and you're STILL shearing a grade 8 bolt, somethings bad wrong. I'd suggest taking the tractor/hog out in the field, with PTO OFF and make your usual right hand turn, the same way and sharpness that's shearing the bolt. Mid turn, STOP the machine and get off to look everything over. Somehow your turn is putting a u-joint in a bind such that the slipclutch can't protect the driveline.

Most shearbolts are grade 1 from what I can tell.

 

[djradz]

Not real experienced with tractors yet but if you've got a working slip clutch and you're STILL shearing a grade 8 bolt, somethings bad wrong. I'd suggest taking the tractor/hog out in the field, with PTO OFF and make your usual right hand turn, the same way and sharpness that's shearing the bolt. Mid turn, STOP the machine and get off to look everything over. Somehow your turn is putting a u-joint in a bind such that the slipclutch can't protect the driveline.

Most shearbolts are grade 1 from what I can tell.

Have to agree. This just doesn't sound like a problem with the 3-pt arms not having enough slack. Any movement, or lack thereof, should be accomadated by the universal joints in the PTO shaft. I'd check: 1) to make sure the blades don't bottom out in the soil, 2) the gearbox is on tight, 3) there is not some way that the shaft is binding.

Good Luck.

 

[Soundguy]

I agree... if you are shearing a 1/2 gr 8 bolt and there is a slip clutch.. this is just an accident waiting to happen.

To the original poster.. did you cut both sides of the pto shaft? What aren't you telling us? A slip clutch should have slipped before the 1/2 gr 8 bolt sheared..

Only on turns... Is the stump jumper loose and letting a blade contact the ground or support / deck ???

Soundguy

 

[tf116]

soundguy: I don't think that my hog has the stumpjumper on it....all there is a flat round plate(1/2"thick?) with 4 holes in it.....with blades bolted to 2 of them....and center stud attaching it to gearbox....
brushhog is sort of flimsy, but runs smooth as silk after it starts....
ALso have a brushhog...brand name is bushhog and it has what looks like a bowl on it...which I always figured was for rocks and stumps..?.....but its not handy or i would try it out...only 5' width.....
6'er has a chain going to back in case of dips and such, allows the hog to flex and bend...its missing the wheel on the back, but i always set it so that back is slightly off the ground and front is higher.....have used it like this for a year or two on old farm...and
other than it being a rusty yellow color, I can't think of anything else to tell you...

 

[tf116]

oh , yeah I forgot to say that I cut both pto shafts....thanks for imput ...Mike

 

[greg_g]

I'm gonna guess you have an unsplined (smooth/round) transmission shaft on that rotary cutter. Because what you're describing shouldn't happen with a splined set. If so, another guaranteed bolt-buster is a rounded-out set of bolt holes. Egged-out holes give the clutch housing an opportunity to slam against the bolt, which in turn slams against the hole in the transmission shaft - and vice versa. If the PTO shaft isn't cut right (or is bent), that would explain extra torque when turning. I think loosening your lower lift arm stabilizers(for more sway) will just make matters worse.

New clutch and new transmission shaft are the proper fix, but expensive. Field-expedient fix (read cheaper) is to overbore the set of holes, then use a larger diameter bolt. Since the clutch should slip before the bolt breaks, the size of the replacement bolt should not matter.

//greg//

 

[Farmwithjunk]

soundguy: I don't think that my hog has the stumpjumper on it....all there is a flat round plate(1/2"thick?) with 4 holes in it.....with blades bolted to 2 of them....and center stud attaching it to gearbox....
brushhog is sort of flimsy, but runs smooth as silk after it starts....
ALso have a brushhog...brand name is bushhog and it has what looks like a bowl on it...which I always figured was for rocks and stumps..?.....but its not handy or i would try it out...only 5' width.....
6'er has a chain going to back in case of dips and such, allows the hog to flex and bend...its missing the wheel on the back, but i always set it so that back is slightly off the ground and front is higher.....have used it like this for a year or two on old farm...and
other than it being a rusty yellow color, I can't think of anything else to tell you...

I'm still trying to decipher some of that post....

If I'm ready correctly, "a flat round plate (1/2" thick) with 4 holes in it....with blades bolted to 2 of them....and a center stud attaching it to the gearbox..." That sounds like a STUMPJUMPER.

The 6'er....First thing that begs for correction.... It's common practice to set the REAR of the mower an inch or 2 HIGHER than the front so you don't have to RECUT everything the leading edge of the mower has already cut. Then I question the practice of using any mower without a tailwheel. It's probably tough to maintain a constant cutting heighth without one. At least, it's probably tough to keep the rear of the mower from scalping when your front tractor wheels go over a rise of any sort.

Are you hitting dirt with the blades when turning? (Or even when going in a straight line?)

Any way of knowing if the slip clutch is original equipment or a later addition? Are the holes in the clutch and the holes in the shaft it's attached to the same size?

I'm starting to envision that mower swinging to one side when you're turning, and hitting a windrow of clippings from the previous round, suddenly throwing quite a load on the blades, shearing the bolt. (Even though the slip clutch SHOULD save that bolt) A litany of other problems cause the bolt to let go. (Back to the holes in the shaft vs. slip clutch...)

 

[tf116]

The PTO shaft and Clutch were bought after the one that came with the hog got twisted and wouldn't slide...
The nonsplined connection?is loose, not sure if holes are elongated or not...
I like to have the front of mower higher so that it rides the brush down and then cuts it.....but I also have the rear raised to allow cut grass,etc.to flow out under rear of mower....
Do not think that it is clumps of grass causing the shearing .....it shears when there is basically no grass under it .....it goes over multiforal rose bushes as high as tractor, or hits rocks or stumps or whatever....no problem....until get to making turn.........under really no load....and then pow!.....
also I have the rear attached to top link with a chain so that it can flex with terrain.....haven't noticed any scalping of dirt....
As so as I get my forge set up again, I'm going to fix tailwheel...
If I had the money I would just trade it for an 8footer...tag along....
only got another 35-40 acres to go and i'll be finished with hogging this year...
Thanks for all imput and I apolize for not being as clear as I would like to be....
Mike

 

[tf116]

I just came back from checking out hog again, the holes in the shaft and slip clutch are both wallowed out....maybe the hog is ok while it is under load and everything is tight or torqued up and then when I hit open grass(no load)then the blades speed up and pop the bolt.....
I think that I will rebore the holes and go with a larger bolt , shouldn't hurt anything as long as slip clutch is working......thanks for all the input and concerns........Mike

 

[Soundguy]

The elipsed holes are a problem... If you do go to a bigger bolt.. try a grade 5 or 2, and get that slip clutch adjusted.

The tail wheel missing is no good. FWJ is telling you right.. the rear of the mower a tad higher is pretty much status quo with rough cutting... That hog will ride the brush down..

Yes.. the round plate is a stump jumper. If it just had a plain blade carrier.. it would be 2 blades bolted to a bar that was bolted to the output shaft of the gear box.

My guess is the blades are contacting deck or ground when turning..

Soundguy

 

[tf116]

Thanks to all imput...I now know a bunch more about brushhogging and brushhogs..so thanks again....I really appreciate it....
I'm still not sure about how to adjust the slip clutch though.....it is slipping some in heavy brush and grass....I'm still curious about the grade 8 bolts....I had a 80+HP tractor with an 8' blade on rear....kept breaking the hookup pins...so I ended up using 5/8"grade 8 bolts thru the blade and to the lift arms...had to use big washers ,as they where very loose...I graded out roads and used blade for a very,very long time...only broke one bolt when it hooked a tree or something...
I'm not so sure that the grade 8 bolts that I am buying are truly grade 8......
Anyway thanks again for all the info....I really appreciate it.....Mike

 

[greg_g]

I'm not so sure that the grade 8 bolts that I am buying are truly grade 8......

A GR8 bolt will often be color coded - at Rural King for example they're blue (as opposed to gold for GR5 and silver for GR2). But regardless of color, a GR8 bolt will be identified by six lines on the hex head looking like spokes on a wheel. A GR5 will have three lines, looking like a fat Y. GR2 bolts have none.

//greg//

 

[Travis_R]

I've gotta ask............................


Just want to make sure we are all talking about a "slip" clutch and NOT an "over-running" clutch, or as some say, over-running "coupler"............???

I just had to make sure.........

Travis R