shear pins on brush hog:

[tf116]

I have a 45HP tractor and a 6ft.Condor Brush Hog have replaced blades and installed a slip clutch.....but I keep shearing pins....have hogged around 8 acres? and used about 20 pins.....
Can anyone tell me what is happening?....at a dollar a pin and 30 or more acres to go, it starts to get expensive and tractor supply dealer only had 12 in stock...
cutting mulifloral rose, and other small stuff, not any thing to cause a shear....hog is not setting too close to ground,I'm at my wits end....Thanks for any imput.....Mike

 

[IslandTractor]

I presume you are using the correct size shear bolts, otherwise something is definitely wrong. Is the mower gearbox OK, lubricated etc? Could a blade be bent or wobbling so it hits the ground? I am really grasping at straws here so will sign off and wait to see what more experienced guys have to say. If you don't get a response from Soundguy pretty soon send him a PM.

 

[Neophyte]

I don't have an answer for you but I do have a silly question. I always thought a slip clutch was used in place of a shear bolt and vice versa? I always thought it was one or the other. If you use a slip clutch, do you still keep a shear bolt in place or do you replace it with a Grade 8 bolt?

 

[tf116]

acually you have to use a shear bolt (grade 5)with the slip clutch.....thats how it is attached to the brush hog......then the other end of clutch is attached to PTO shaft.......
will check the blades and gear box tomorrow...but haven't hit anything to bend the blades and they are fairly new......plus I replaced the bolts and nuts....
It seems to shear the pins when you are just mowing grass....not anything tough......will check it out somemore tomorrow...Thanks....Mike

 

[Skaning]

You also might think about your shear bolts. There is a lot of counterfeit stuff out there and incorrectly marked. It's better than it was but still a problem. You can wind up with "Grade 5" that are way softer than they should be if your dealer is using a low bid supplier. Problem is, about the only resource the average person has is a trustworty source.

John G

 

[greg_g]

acually you have to use a shear bolt (grade 5)with the slip clutch.....thats how it is attached to the brush hog......then the other end of clutch is attached to PTO shaft.......

There is no such part as a shear bolt in a PTO slip clutch driveline, especially if the clutch and transmission shaft are both splined. There is one bolt to hold the clutch housing to the transmission shaft, but the fact that there are splines there make it nothing more than a fastening bolt - not a shear bolt.

Now if you've got a smooth shaft and clutch housing, the bolt is STILL considered a fastening bolt. That is however, assuming the slip clutch is actually cleaned and adjusted properly to match the tractor's PTO hp rating. If not, THEN your fastening bolt stands a good chance of turning itself INTO a shear bolt.

Did you in fact clean the friction discs and adjust the release point before you used it on the rotary cutter? It's recommended this be done twice a year; in the spring before taking the cutter out for the first time, then again about half-way through the mowing season.

//greg//

 

[Neophyte]

acually you have to use a shear bolt (grade 5)with the slip clutch.....thats how it is attached to the brush hog......then the other end of clutch is attached to PTO shaft.......

I realize a bolt is still required on the rotary cutter side to hold the driveline on a smooth shaft but I thought you bypassed the shear bolt aspect of it by using a stronger Grade 5 or 8 bolt when using a slip clutch. I thought if a slip clutch is adjusted properly, then you shouldn't need a shear bolt.

Also, I thought a Grade 2 bolt was typically used for the shear bolt. Something is definitely odd if you are popping Grade 5 bolts that easy. Do your shear bolt heads have 3 radial lines or no lines?

Can you rotate the rotary gearbox easily by hand?

 

[Soundguy]

IMHO.. greg and the other hit on a lot of good points.

I think perhaps you have not done the initial slip and adjustment onthe slip clutch. if it is adjusted correctly.. i think it should slip before a grade 2 bolt breaks.. and deffinately a grade 5.. if you are popping grade 5 bolts.. the clutch is not slipping.. and it is just like you are using gr5 bolts in a shear pin setup.. which can be brutal to your tractor and mower.

Also.. while many places sell 'shear bolts'.. unless they are specialized.. I usually just hit the bulk bins and buy a handfull of gr 2 soft bolts.. and get a handfull for a couple bucks..

Check that slip clutch ASAP.. slip it.. then tighten according to it's chart... and try some gr2 bolts once it is setup.. if those pop.. use the gr5. they should -never- pop once the clutch is correctly set to slip at about what a gr2 pops at.. or a bit less.. etc. )

Soundguy

I have a 45HP tractor and a 6ft.Condor Brush Hog have replaced blades and installed a slip clutch.....but I keep shearing pins....have hogged around 8 acres? and used about 20 pins.....
Can anyone tell me what is happening?....at a dollar a pin and 30 or more acres to go, it starts to get expensive and tractor supply dealer only had 12 in stock...
cutting mulifloral rose, and other small stuff, not any thing to cause a shear....hog is not setting too close to ground,I'm at my wits end....Thanks for any imput.....Mike

 

[tf116]

Thanks for the input...I have to admit that I didn't take the clutch apart and clean it...only loosened the nuts until I could slip it and then tighten them up again....I does slip in grass, but I have no idea about how to set the slip or adjust, or clean clutch....
I just bought the clutch and installed it and went to hogging....It hasn't been used for a year or so.(no tractor and moved)....
Now have a new farm that is run down and all growed up.....
Where would I find info on setting clutch?.......Thanks for all the input....
And I do know how to tell the different grades of bolts.....by markings....Mike

 

[greg_g]

Is it painted yellow, and does it have eight spring tensioned adjusting bolts around the circumference?

What is your tractor's PTO hp rating?

Bolt hardness is identified by how many bars are on the top of the hex head; none on GR2, three on GR5, five on GR8 - I think. Farm stores will sell them color coded; GR2 silver, GR5 gold, GR8 blue

//greg//