rebuilding brush hog

[91redfrod]

hey all, got a 4' john deer brush hog style mower, well used to the point of needing some work on the gear box, i flipped it up and got the cotter pin and castle nut off the spindle end but can't seem to get the saucer/blade assembly loose, it looks like it hasn't been removed since new. i did heat it & hammer on it. any advice would be great. Thanks

 

[Wbk]

Hi by saucer do you mean belt pulley? If so are there any holes that you can use for puller bolts? I rebuilt a very old Hustler gear box last year and the pulley was seized on to the shaft as well, I used a lot of heat(Your probably going to replace the bearing and seal) and a very strong puller,when I got it off the pulley was to distorted to re-use. Be careful not to damage the shaft, you might have to cut the pulley off if you can buy a replacement. I hope this was of some help, good luck.

 

[Orange Tractors]

Lots and lots of your favorite penetrating oil on the shaft and splines, because you are probably right, it hasn't been apart since new.

When I took the blades and flywheel off my 5' BMB brush hog (no stump jumper on it), I did the penetrating oil, then put a 4x4 wooden block on the end of the shaft (to protect the threads) and hit the end of the shaft with a sledge hammer to vibrate the flywheel assembly loose. It also helps to have some pressure behind the flywheel, just like removing the flywheel from a Briggs & Stratton engine, only larger.

Be careful, the blade assembly weighs more than you want to drop on your foot. I hung mine from my engine hoist so I could see what I was doing.

Robert

 

[Eric McCarthy]

Can you put up a picture of what your describing? It sounds like your talking about the stump jumper which looks like a saucer and when you said blade assemply I think thats what your reffering too. If it is indeed the stump jumper its more then likely welded on the shaft.

 

[91redfrod]

I'm a little laid up from a wound but i may be able to better describe the saucer,it's attached to the shaft in the middle through a 3/4" hole,maybe 14" across, it's dished and has the pivoting blades on opposite sides, the shaft it's mounted to looks like a seperate piece, it's hard to get a good look behind the saucer but i can see the thicker steel center pc the shaft passes through,maybe 4" thick and 4" around... the whole thing is stuck together, i can't tell, where do the pcs come apart? thanks for the ideas

 

[Eric McCarthy]

If the blades are bolted to this said saucer then yes its a stump jumper and its welded to the shaft. Does it look like this???

 

[91redfrod]

That's it, thanks for a good pic, so if it's welded...should it be disassembled from the top down? i can get the bolts free that hold the gear case...

 

[Russell King]

I do not believe that the Blade Carrier (Stump jumper) is welded to the shaft. I looked at my manual and the following is the instructions for removal:

Blade Carrier Removal
Remove cotter pin and loosen slotted nut on gear box shaft. Loosen but do not remove the nut until the blade carrier is loosened. Use a suitable two-jaw gear puller to pull carrier against tapered gear box shaft. If gear puller is not available use long bar inserted through blade bolt access hole with end against rotor bar. Strike opposite end of bar with sledge hammer. Rotate blade carrier 180 degrees and repeat process.

What the "if gear puller..." part is trying to say is - take the blades off and use those two holes to put a long threaded rod up through the hole and put a nut on the top side to hold it in place. Then do what you can to hit it to drive the whole thing down.

I think if I was doing it I would spray some pentrating oil on the upper side of the stump jumper trying to get it to run down the shaft. Then loosen the nut (assuming there is one at the center of rotation). Take the two blades off. See if I could rent a strong puller from the auto parts or rental place that fits. If not install some long high strength all thread with nuts above the blade rotor bar (there is a bar above the stump jumper probably welded to the stump jumper) or into threaded holes if there are any in the assembly. Then get a fairly strong C-channel (or weld up a strong back) that will span across these two and put holes for the all threads to go through. Then tap the center point of the bar to install a high strength bolt. Install this onto the long all thread with nuts and washers and then tighten the bolt to try and pull it off by tightening the center bolt against the shaft.

A little pressure, a little heat, a lot of penetrating oil, a lot of patience.

Don't try to get it off all at once or you might deform the assembly. If it is a tapered shaft it will let go all at once so be sure to leave the nut on the end of the shaft to keep it from falling on you. It might be easier to turn the whole cutter upside down.

Good luck

 

[91redfrod]

Hmm.. sounds good, i think that is what i am seeing, a clear gap around where stump jumper saucer thingie meets the shaft, if it where welded it would have to be on the underside of saucer...can't see much up there...i do think your puller idea is sound. i need several days, just had a hernia surgery and moving slow..not really able to tear this down yet, but soon and in the meantime learning how to go about it, thank you!

 

[Russell King]

. i need several days, ...

Perfect amount of time for penetrating oil like Kroil, Deep Creep, PB Blaster or whatever is your favorite to soak into the area if you can mosey out and spray it down with something. I would at least give it a day or two to soak so hopefully you can get it sprayed some before you really feel good enough to work on it.

Even in the picture from Eric McC you can see the castle nut and cotter pin (I think).

 

[skeets]

Where's captain candle wax on this???

 

[Eric McCarthy]

My info was kinda lossly based off of eyeballing my older Woods M4 bush hog which is about 30 years old. Mine seemed like the stump jumper was welded onto the shaft. I didn't really see anything that looked like a way to remove the jumper to get to the shaft. My fat head didn't really fit between the jumper and the bottom of the deck.

 

[Stubbyie]

I've pulled three different stump-jumpers off brush-hog shafts and had trouble every time.

You said you used heat. My bet is you didn't get it hot enough. And if you did the seals are ruined. Plan on replacing all seals no matter what, once you get it apart. And I'll bet heating alone won't be enough.

No penetrating oil I've used (everything available in my area; Kroil is best) has been successfull.

Tried hydraulic "gear puller" and bent the stump jumper. Managed to strip the threads off a BIG manual puller.

At the time talked with two different local tractor shops. Both told me that if not brand spanky new they don't even bother trying to pull the jumper. They just cut it off with a torch and start over. The gear box is really what's valuable.

By the way, I wound up cutting all mine with a torch like the shops said would work best.

Note finding a replacement locally might not be easy and if so will likely require changing blades. Better to buy replacement jumper and blades matched to size of your shaft and brush hog dimensions. Finding the correct blade (length, hole size, direction of rotation, droop or offset) will be another interesting experience.

Like another poster mentioned it's supposed to be like pulling a flywheel off a small engine. If you ever get the jumper to move, expect it to pop off suddenly with a lot of force. Don't get hurt. I think I'd be inclined to chain it down loosely enough to move but prevent it popping up and getting you. Keep in mind this is what I'm told, never seen one actually pulled off as designed.

All things considered, can you use the 'hog as-is with perhaps only changing or sharpening the blades?

If you find a way to get the blasted thing apart please post back and advise about your experiences so all of us can learn.

 

[Tire Biter]

The O&M manual on my mower tells to drill a 2" hole in the deck right next to the gearbox so you can get a long punch or chisel in here and pound from the top down. Then just patch the hole after for future access. If the MFGs would have assembled it with some never seize, these things might not be so hard to get apart.

 

[91redfrod]

Ya maybe there's options i haven't considered...i bought the BH used and was told a bearing in the gearbox would need replacing...well when i got it hooked up to the tractor and mowing it was noisy and had a lot of vibration on the horizontal gear box shaft, where this shaft shows thru the backside of the gearbox there is play and after running it for 20-30 min. i could see some metal shavings coming from the back of gearbox, very fine but still metal, so i know i need in there and figured that was the way to disassemble...i have never done this before...but i have made mistakes before...could be the whole purchase was a mistake but now it's abit late for that assessment..is there another way into the gearbox? it does look like a huge snap ring on the back side of gearbox, if i remove it what's inside? thanks guys for all the information..like i said before, since getting doctored last week i'm moving slow...when i'm moving...but that's OK since i always seem to go to fast and then learn...this time i'll try to learn 1st...

 

[Eric McCarthy]

You can get a brand new universal gear box for about 120 bucks if you can't get into yours or find parts to repair it with. I know Agri-supply sells them that cheap and can ship.

http://mower-blades.agrisupply.com/search#w=gearbox&asug=gear

 

[Russell King]

View attachment gearbox.pdf

The attached is a cross section through a gearbox on my cutter. Hopefully you can open it (PDF file).

It shows a cover on the input shaft side that should come off and expose the inside. From looking at this it looks like the input shaft and cover and gear may all come off at once. I have never delved into one of these but it seems that they would all have some cover on both shafts and since the input is on top that is where I would start.

 

[lsmurphy]

The O&M manual on my mower tells to drill a 2" hole in the deck right next to the gearbox so you can get a long punch or chisel in here and pound from the top down. Then just patch the hole after for future access. If the MFGs would have assembled it with some never seize, these things might not be so hard to get apart.

How about two 3/4" holes from the under side near the shaft so that a puller could be used?

 

[Russell King]

From looking at diagrams in my book and thinking about what IsMurphy said it looks like it may be possible to cut some holes in the stump jumper "sheet metal" and use a jaw puller over the blade carrier hub (#19 in the first PDF and shown in the middle of #1 on this PDF) and pull it off.
View attachment 7317

 

[Stubbyie]

Your report of seeing metal particles out the back of the horizontal shaft has me wondering about your gearbox. Not sure I've seen such an animal. Got photos?

My gearboxes on brushhogs are sealed on the off-side from the input.

If the shaft is passing through it sounds like the rear or offside shaft support bushing / bearing has failed.

Even--maybe especially--on a chunk of steel like the stumpjumper if you start cutting holes to use a puller you may create a balance problem. I know when a blade loses a chunk it will unbalance and scare the heck out of the operator: things happen pretty dang fast.

When I tried pullers (a failed effort per post above) I used 3 chain hooks spaced around the jumper instead of creating new holes.

Before going further try filling the gearbox with a tube of grease-gun grease. You may not have lube aboard. For known leaky gearboxes I also mix a bottle of syrupy super-thick motor honey ($2 a bottle at WM). Same theory as using a banana in an old Chrysler differential.

Otherwise, if you can't find a way to live with it, I'm back to thinking the stumpjumper will have to be cut off. If you do replace the jumper I can't emphasize enough to get the replacement complete with blades to fit your shaft(s) and deck size.

If you do get it all apart go ahead and check the U-joints for excessive play or wear. A 'new' tight gearbox-seals-bearings might stress other ancient parts of your driveline and create an additional failure.

Please post back how you proceed and what works--or doesn't. I'd like to know how you ultimately manage the stumpjumper.