Brush Hog mods

[scootr]

In the skid steer mowing thread the topic of rotary chain mowers came up.
I got to looking around and found a couple of videos from guys who had cut their blades back and added chains.
Found an old model 12 BH 5 ft and went at this mod. Nothing pictured here is pretty. We just wanted to experiment with the chains or cables.
We mow rocks at times and it plays heck with the steel blades.
This picture here what we saw in our initial (fact or fiction) search

 

[scootr]

Here is the victim. lol
We cut the blades off (they were welded on!)
Drilled a 1/2 inch hole in each end and attached some chain.

 

[Lineman North Florida]

I'm anxious to see how well it processes the material it cuts and overall how big of material it cuts, good job on your test project so far.

 

[ptsg]

What size of chain did you end up going with? Looks small in that mower. Cables won't work very well because they don't really have much weight at all.

For anyone interested, here is one of these cutters working:

Also, how one of these mowers look underneath and on the top:

 

[ptsg]

Taking some bigger trees here:

 

[scootr]

We used a 70 grade 3/8" chain. That is what we had on hand.
We are not cutting anything as big or tough as what you show in the video.
That is some impressive brush hog action.

 

[ptsg]

We used a 70 grade 3/8" chain. That is what we had on hand.
We are not cutting anything as big or tough as what you show in the video.
That is some impressive brush hog action.

Those on the video do require some serious tractor behind it.

I've done 3" of soft mimosas before with my 35hp tractor and do all kinds of 2" stuff regularly.

 

[5030]

Think I'd attach the chains to the stubs with threaded repair links of equal size so when the chains wear out they will be easily replaceable.

 

[scootr]

Think I'd attach the chains to the stubs with threaded repair links of equal size so when the chains wear out they will be easily replaceable.

I ended up with hardened 1/2 bolts so I could change chains easily. I looked at threaded links and U bolts. Both could be used.

 

[2manyrocks]

Could you please post a close up picture of how the chains are attached? It seems like to me that you'd want to sandwich the chain like the housing does in post #4. I start to worry that a bolt head may shear off and the chain go flying.

 

[scootr]

Could you please post a close up picture of how the chains are attached? It seems like to me that you'd want to sandwich the chain like the housing does in post #4. I start to worry that a bolt head may shear off and the chain go flying.

I will get a pic later today.
Hardware is grade 8 bolt, nut, thick washers, and lock washer. Torqued to gawd almighty tight
The fastener is much harder than the chain or the blade.
We will do a test and check it... then a longer test and check it again until we are certain it's not going anywhere.

 

[ArlyA]

Interesting setup.

 

[2manyrocks]

I'm not an engineer.

I suspect all of the shock load from the chain spinning would be on the head of the bolt in the first picture. Having the chain flying in all sorts of directions as it chops different material is going to put a lot of shock load on it.

If the chain was between two supports as in the second picture, part of the shock load would be borne by each of those two supports. Not as much load directly on the head of the bolt.

Another thing that concerns me is the OEM pivot bolts on a brush mower are pretty dang substantial, and now a much smaller bolt is being introduced into the part that actually does the cutting.

Seems like there is too much opportunity for something to go very wrong.

 

[ptsg]

Maybe this is a better picture:

I would be a lot more comfortable with a similar setup. These cutters will take a beating but will also beat the living cr@p of that they hit. Things need to be strong.

 

[2manyrocks]

What is the red/gray device used to connect the chain to the pins on the dual flywheel assembly, please?

 

[ptsg]

What is the red/gray device used to connect the chain to the pins on the dual flywheel assembly, please?

One of these connecting links but got a little bit of over spray.

 

[2manyrocks]

I'm not familiar with those connecting links, but they look like they'd have much better ability to handle repeated shock loads than the head of a single bolt intended for use as a fastener.

 

[ptsg]

I'm not familiar with those connecting links, but they look like they'd have much better ability to handle repeated shock loads than the head of a single bolt intended for use as a fastener.

I haven't used them either but I do see them being used on all high end cutters, so they must handle it abuse fine.

Mine uses a pin straight through the chain link. Hard to see on the picture. I may take some better ones once I put the cutter on the tractor again.

 

[2manyrocks]

It seems to me that this has to be carefully engineered and fabricated to be safe.

Relying on a bolt head to handle repeated shock loads when that bolt may be intended to handle a fixed static load could be the recipe for an unintended shear of the head. If the chain flies loose with someone standing near the cutter, it could amputate a limb.

 

[ptsg]

With proper chain skirts and with the cutter on the ground, if the bolt breaks, the chain should stay contained within the cutter.

I'm running 1 link short on my set of chains because I broke one on the links on one of the chains. Both broken pieces landed exactly where it broke. I then cut 1 link on the other good chain and have been running since.