Rotary Cutter Brush Hog Blades COMING OFF

[Asar2525]

I seem to be having the opposite problem of most people. I have an old brush hog (FMC Sidewinder) that I've used for the past 4 years. I use it for pasture mowing and cutting down weedy parts of hay fields, but also for mowing brush that grows up in our woodlot.
So far this year I have had a blade come off 4 times. I've had good luck finding the blade but keep losing bolts... I just tried putting Nord-Lock washers on both blades but had a blade come off even with those! Every time I tighten the nuts I use a 3/4" drive T-bar with a 3ft pipe and torque it down as hard as I can. I'm nearly at wits end and am seriously considering welding the nut on the bolt. Any suggestions would be greatly appreciated.

 

[countrybumpkin]

Are you sure your using the correct bolts for your cutter, most of the side winders I’ve had use the bolts with a flat side.

 

[Asar2525]

I'm using the type with a raised portion that keeps the bolt from spinning. It looks like someone redid the bolt holders at some point before I owned it.

ATRC11 Blade Bolt Kit at Tractor Supply Co.

I would think this would work fine since it keeps the bolt from spinning.

 

[countrybumpkin]

Redid the holders as in how?

 

[Asar2525]

From what I can tell the holes in the original stump jumper got stretched out so there is a 3/8" plate welded on the bottom and a 3/8" plate welded on the top of the stump jumper that holds the bolt. These each have a 1 1/8" hole drilled in them and the bottom one has a small part machined out for the crimped "tab" on the bolt that keeps it from rotating. It's very heavy duty.

 

[atcNick]

You probably need a cotter pin through the bolt after you put the nut on. Do you have a hole in the bolt at the end? If so, use a castle but and a cotter pin

 

[Asar2525]

atcNick, There is no hole for a cotter pin and it isn't a castle nut.

 

[atcNick]

Here’s kinda what it should look like

 

[atcNick]

atcNick, There is no hole for a cotter pin and it isn't a castle nut.

Hmm... man. I would think that’s standard. I wonder how easy it would be to replace the shaft bolt. I had the same problem as you. It was constantly falling off... once I realized what the cotter pin hole was for I haven’t had an issue since

 

[Zebrafive]

I would get another brush hog, before something, or SOMEONE, gets hurt. I would NOT take the risk of keep using it. You have been lucky four times. Two would have been my limit.

 

[Asar2525]

Zebrafive, trust me I would LOVE a nice, new heavy duty brush hog but that certainly isn't in the budget right now.

To everyone else, I may end up torquing it down then match drilling a hole through the nut and bolt and putting a cotter pin through that. Thoughts?

 

[countrybumpkin]

This is what the sidewinders I’ve had uses.

If you have a extra 3/4” of thickness to go through do you have full thread engagement in the nuts? Are you sure they are tight enough ?

 

[Zebrafive]

Drill your bolt, but get a castle nut, that will allow more options to "pin" when it is tight, most you can be off, to get the cotter pin in, is less than one flat of the nut. You should be able to tighten a little more and get it pinned.

 

[Fuddy1952]

With a castle nut and cotter pin it couldn't come off.
I had one crazy thought though. It sounds like when the blade hits something hard like a small tree, etc. is when that is when it spins the nut off. It's like it's backwards like you said the opposite problem most people have. Could it be (for example) from the factory it had left hand threaded blade shaft and was replaced with right hand?
Check that and be sure it's turning in correct direction with PTO.

 

[Asar2525]

Countrybumpkin, the nuts are fully engaged by about 1 thread.
Zebrafive, I'll measure the thread pitch tonight and try to find castle nuts. It looks like Fastenal has them.
Fuddy, I don't think there's any way the direction could have been reversed. It certainly isn't on my tractor. I will check tractor supply and see if the sidewinder bolts they sell are LH thread, that's a good thought. It is certainly hitting rocks/stumps/trees that the blades will come off.

 

[countrybumpkin]

Ok, I don’t think you’ll have enough threads then for castle nuts.

My guess is you’re just not getting them tight enough , or the lock washers are breaking and then the bolts are loose.

 

[Asar2525]

If I put a castle nut on I can take off the Nord-Locks which will give me ~1/4"

 

[countrybumpkin]

You could I guess, but the main thing the cotter pins do is a safety , they are not intended to keep the nut tight.

The torque specs for 1-1/8” nuts start at about 400 and go up to over a thousand depending on grade and thread.

 

[Asar2525]

I would say with the 4' of leverage I tightened them to an easy 500 ft lbs. I supposed I could throw a rock bar in the open end of the pipe and get to 1000 ft lbs.

 

[Hilbilly]

Maybe the nuts aren't coming off and the bolts are breaking. If that's the case you could try using grade 8 bolts.