The ultimate bush hog

[sandman2234]

Ok, getting tired of tearing up bush hogs. I haven't torn up any gearboxes, but am really hard on sheet metal and uprights.
I purchased the main gearbox (1input/3outputs) and a single right angle gearbox off the shelf of a now defunct business. Both are new, but starting to show a little rust on the unpainted surfaces.
I saw a guy on a machinist forumn build his own bush hog, for pretty much the same reasons as me, tired of tearing up lightweight bush hogs. I am probably a little harder on them, but apparently he must have torn one or two up in his time. Anyway, on with the question...

If you were going to build a super strong bush hog, PTO, what would you use for the components, how would you know how big to make the stump jumper (in diameter), how many blades, 2,3,or 4? How long of blades would be best? Shorter or longer, which has the capability of doing a better job of clearing rough woods and thick briar patches? Which design of pto shaft has the least likelyhood of twisting?
Hot dip galvanize would make the whole thing last a lot longer and is available locally, provided the pricing hasn't gone thru the roof like a lot of other metal suppliers.
Here is the link to the discussion we had a while back.
Welcome to the Manufacturing Forum: Summer, and the grass is growing, but I'm ready (finally) [finished my Bush Hog]

David from jax

 

[sandman2234]

Welcome to the Manufacturing Forum: Bush hog project update

Just located some more on the build of that other bush hog. Thought you guys might like to see the pictures, and maybe spark some ideas.
David from jax

 

[Highbeam]

I bought a cheaper mower and then after the uprights failed from backing into brush I went ahead and improved the uprights to an HD captive pin design. I see this as a major improvement over the OEM. Don't drop it on your fingers when you're fabricating, I crushed one of mine into bone soup.

 

[browns40]

Hi sandman,

It seems to me that the overall sturdiness of the cutters is usually directly related to the gearbox HP rating...

A 40 HP gearbox isn't intended to shred 2" material... a 90 HP isn't intended to shred 4" material... not to say you can't chew up bigger stuff with a lesser gearbox occasionally, but it won't last.

Likewise, the frame on the lower gearbox hogs really wasn't intended for dealing with a whole lot of tree pushing (probably none are!), it's meant to keep the "shrapnel" in once the blades obliterate it, and smaller bits for smaller gearboxes at that.

I guess what I'm saying is like with anything, you usually end up getting what you pay for.

I would guess a stump jumper 40-50% the overall widthe you build the deck would br pretty good; also 2 blades will be cheaper to replace than 3 or 4 (plus easier to balance); those "star" & "triangle" shaped splined shafts seem really nice

I would look at top of the line cutters & borrow their ideas for the machine rating you are looking for.

Sounds like a fantastic project--look forward to the results!

 

[sandman2234]

So how do you know the horsepower rating of a gearbox, especially if you buy a hog with one on it used?
David from jax

 

[Highbeam]

"I would look at top of the line cutters & borrow their ideas for the machine rating you are looking for."

That's exactly what I did and I highly recommend it. Even thickness of metal. There are some obvious changes in design philosophy when you step up from economodel to obliterator. 5x the expense too.

I would suspect that the serial number on a gearbox could be tracked back to the manufacturer for HP rating.

 

[browns40]

Good question on the gearboxes...

Seems to be a correlation with overall physical size of the gearbox with the duty rating of the cutter; also size & # of bolts attaching the gearbox to the deck of the mower...

That said, I wouldn't trust "eyeballing" too far!

Every manufacturer I've researched (JD, Woods, Bush Hog, Rhino, Land Pride, etc.) advertises gearbox rating for each duty line of their machines... most do metal thickness... oftentimes driveline rating & blade tip speed... a search of the manufacturer's lines should give you a close (if not exact) idea of the rating on the box.

As far as hot dipping it, I think it'd be an exercise in futility... to build a cutter that would'nt dent when a 3 lb piece of steel or granite smacks it going 14,000 feet per second would entail building a cutter that weighs more than a tractor, or incorporates some military technology!

Good Luck!

 

[sandman2234]

The hot dip galvanize is to protect the bush hog from one of the worst enemies, RUST! I don't have enough roof space to keep all my junk out of the weather and that would make it one less to worry about. I did one about 15 years ago for a neighbor, and his is still rustfree.
David from jax

 

[Jim_L]

Brown MFG Makes the best bush hogs.
Ive got a 672

Brown Mfg Corp Homepage

 

[browns40]

Wow! That is some cutter!