Another brush hog mower question

[JimR]

I borrowed the neighbors brush hog to mow their fields and my woodlot this week. First off, I had to tear it apart to clean up the slip clutch discs and replace two u joints. So far in three days I have sheared off (6) 3/8" grade 8 bolts that hold the swinging blade assembly onto the lower shaft. The shaft and blade unit is splined and the bolt just keeps it on the shaft. I now have number 6 bolt on it. I managed to make it through the rest of the day without shearing off the 5/16" bolt that I put in. The hole in the shaft and blade assembly is 3/8". I wonder if maybe the 3/8" bolt was just too tight with no give and that may be what caused them all to shear off. I have been knocking down a lot of small trees with it. Here's a good before and after shot of the top of the hill that I am doing. I only have another 34-35 acres to do.

 

[greg_g]

I managed to make it through the rest of the day without shearing off the 5/16" bolt that I put in. The hole in the shaft and blade assembly is 3/8". I wonder if maybe the 3/8" bolt was just too tight with no give and that may be what caused them all to shear off. I have been knocking down a lot of small trees with it.

Too tight is better than too loose, but I'm wondering about the 3/8" part. Are you sure it's not a half inch hole that's been oval'd out so that only a smaller bolt will fit? Too much play in a rotating shaft bolt hole is a broken bolt waiting to happen

//greg//

 

[sandman2234]

I think I would take the neighbors bush hog back and spend the money on my own. With 35 acres of that stuff to mow, your probably going to have a lot of repairs to do to the bush hog, and some might not be appealing to the owner. The price of a used bush hog isn't worth the cost of a good neighbor.
David from jax

 

[browns40]

Hey Jim,

ANY CHANCE YOU HAVE ACCESS TO THE OWNER'S MANUAL FOR THAT CUTTER?

Very strange (& dangerous) thing to be happening... should find out the correct torque, bolt grade, and fastening design for that machine.

I would be thinking either you've got a tapered shaft and the pans not seated far enough up on the shaft, or the pan or shaft are worn so it won't seat... or I'm picturing the wrong thing from reading (a pic would help).

 

[Farmwithjunk]

Hey Jim,

ANY CHANCE YOU HAVE ACCESS TO THE OWNER'S MANUAL FOR THAT CUTTER?

Very strange (& dangerous) thing to be happening... should find out the correct torque, bolt grade, and fastening design for that machine.

I would be thinking either you've got a tapered shaft and the pans not seated far enough up on the shaft, or the pan or shaft are worn so it won't seat... or I'm picturing the wrong thing from reading (a pic would help).

I've typed out 3 seperate replies to the original post, then deleted them. I'm having a rather difficult time picturing a mere 3/8" bolt holding a stumpjumper and blades on a bush hog.

I'm like you. WE NEED A PICTURE!

It doesn't take much to confuse me at this time of the morning......

 

[JimR]

I'll try to take a picture of it this morning. The blade shaft and blade base are splined on this unit. The only thing the bolt does is hold the blade assembly up on the shaft. The bolt goes through the hole horizontally. When the bolt brakes the blade assembly justs falls off. It is definetly a 3/8 hole. I tried the bolt in just the shaft. That is the biggest bolt that will fit in it. I wonder if the stumps and small dead wood on the ground jamming up above the blades may be breaking the bolts off. They do not have the manual for it. I do have the slip clutch working on it. This deck has sat idle for at least 10 years. The owners are too old to use it anymore and he is almost blind now. They don't want to sell the farm equipment they have. They prefer to just let it sit out in the field and rust away. It is really a shame as they have a couple of old tractors and haying/agriculture equipment just rusting away. I salvaged the brush hog and hope to swap it out for my labor to do their fields.

 

[Farmwithjunk]

I'll try to take a picture of it this morning. The blade shaft and blade base are splined on this unit. The only thing the bolt does is hold the blade assembly up on the shaft. The bolt goes through the hole horizontally. When the bolt brakes the blade assembly justs falls off. It is definetly a 3/8 hole. I tried the bolt in just the shaft. That is the biggest bolt that will fit in it. I wonder if the stumps and small dead wood on the ground jamming up above the blades may be breaking the bolts off. They do not have the manual for it. I do have the slip clutch working on it. This deck has sat idle for at least 10 years. The owners are too old to use it anymore and he is almost blind now. They don't want to sell the farm equipment they have. They prefer to just let it sit out in the field and rust away. It is really a shame as they have a couple of old tractors and haying/agriculture equipment just rusting away. I salvaged the brush hog and hope to swap it out for my labor to do their fields.

So far, I've kept everything under roof, and out of the weather, but I'm hanging on to my equipment even though I'm through farming for the most part. It's an "OLD" thing. We hate to part with the last remaining link to our glory days. I've got some fine haying equipment that probably won't see duty again. Common sense says sell it. Nostalgia says keep it. My son farms the old place now. He wanted newer equipment. I square baled. He's gone to rounds. He has little interest in my old antiques. I can relate to the old guy wanting his stuff left there, even to rust away. In his mind, there's always that chance he might turn young again and need it. We know better, but that "old" keeps telling us things will be alright. For now it is.

 

[JimR]

Farmwithjunk, I can understand where you are coming from. These folks are the same way.

Here's the picture of the lower shaft. There is 1/2" of play up and down at the ends of the blades. The mower attachment is rocking on the output shaft a bit. There is no back and forth slop in the splines. I used it for another hour today and that 5/16" bolts is still in there. I think the smaller bolt may be the answer.

 

[BobG_in_VA]

.
There are three kinds of men;
1.) The ones that learn by reading
2.) The few who learn by observation
3.) The rest of them have to pee on the electric fence for themselves.

FWJ: I like your motto, I had somewhat the same thing on the wall behind my desk for years. I read:

THERE ARE THREE TYPES OF PEOPLE:
1. THOSE THAT MAKE THINGS HAPPEN,
2. THOSE THAT WATCH THINGS HAPPEN,
3. THOSE THAT ASK: "WHAT HAPPENED.....???"

BobG in VA

 

[Farmwithjunk]

Farmwithjunk, I can understand where you are coming from. These folks are the same way.

Here's the picture of the lower shaft. There is 1/2" of play up and down at the ends of the blades. The mower attachment is rocking on the output shaft a bit. There is no back and forth slop in the splines. I used it for another hour today and that 5/16" bolts is still in there. I think the smaller bolt may be the answer.

I'd try a bolt that doesn't extend any farther than the nut requires. Maybe that bit of threads tailing past the nut is catching on anything it can, helping to snap the bolt.

The thought passed through my mind (and right on past) to replace the bolt with a hardened roll pin that would be flush with the male portion of the splined coupling. Not sure that's such a great idea, but it is an idea none the less.