Well it lasted 2 1/2 years: Bushhog 286 Output Shaft Repair

[Zebrafive]

I rebuilt a Woods gear box. Seals and bearings. I was surprised how loose the mesh of the gears was. Nothing like rebuilding/setup of a ring pinion in an axle.

 

[Zebrafive]

I also would not put a lesser HP gear box on. Time to weigh the cost to repair versus cost to replace.

 

[FTG-05]

Thus far, I've elminated no options. I'm actively looking for a replacement bushhog rotary cutter, Bushhog gearbox part number 70991 and to see if anyone around here repairs gearboxes. As I've said before on this site, the local farm store that used to be the go-to place for decades went out of business a couple years ago.

Also, unfortunately, the only bushhogs that are for sale around here is either used up beaten junk or brand new chinesium-type cutters:

 

[diesel85]

Have you tried a local machine shop?

I've had them R&R all kinds of stuff for me, including making BETTER parts than you could buy.

 

[FTG-05]

Have you tried a local machine shop?

I've had them R&R all kinds of stuff for me, including making BETTER parts than you could buy.

No, mostly because it broke over the weekend and everyone is closed. The only "machine shop" around here is the local welding company; they have a mill and lathe, but I'm not sure I'd call them a machine shop.

They are however, a good source for info on who could repair/rebuild the gearbox if I decide to go that route.

Be careful of supposed "Bushhog" branded gearboxes on Ebay. I saw one for sale and something seemed off. I sent an e-mail to Bushhog corporate asking for confirmation along with a link to the Ebay sale site and got an answer this morning: They don't recognize it.


After looking at used and new bushhogs over the weekend, I now have a much fuller appreciation for the fact that buying my 286 back in 2014 - for $500 - was a flat-out Steal. I've seen used beat up 286s for sale for over $2K right now.

 

[FTG-05]

Found a used cutter for sale. However this picture of the front end of the driveshaft has me puzzled and a little worried:

That's not the standard 1 3/8" six-splined PTO-type shaft I was expecting.

What is that and how hard is it to R&R to the standard PTO shaft end?

 

[LD1]

Found a used cutter for sale. However this picture of the front end of the driveshaft has me puzzled and a little worried:

View attachment 717469

That's not the standard 1 3/8" six-splined PTO-type shaft I was expecting.

What is that and how hard is it to R&R to the standard PTO shaft end?

That looks like a typical 21-spline 1000RPM shaft.

Sadly.....the gearing in the ggearbox is different so I dont think you can just swap shafts.

6' mower with a 540pto usually has a 1:1 or up to a 1.47:1 gearbox.

Meaning the blades will spin 540 rpm or up to 794 rpm. On a 6' cutter (6' times PI) gives you a blade speed of 11000rpm for the 1:1 box up to about 15k.

A box designed for a 1000rpm input is gonna have a reduction box in order to achieve the same/similar blade speed.

Use that box on your 540 and you may not have enough blade speed to even cut

 

[FTG-05]

Thanks for the help LD1, I appreciate it.

According to the manufacturer, this is supposed to come with a 540 rpm gearbox rated at 110 hp. It's the same bushhog as mine except it's one foot bigger (287). In the pics, it appears it's the standard 110 hp Bushhog gearbox i.e. not something else.

ETA: Looked at the Bushhog Repair Parts Manual; according to page 59-1-4 (emphasis added):

"DECK ASSEMBLY (Comer Gearbox)
287 (540 RPM) & 1287 (1000 RPM) Models
Serial Numbers 12-01500 and Above"

But something's funky: according to the pics in the ad, the model number as shown by the Bushhog tag is clearly a model #287, not a #1287. This would indicate the 540 rpm model, not the 1000 rpm version. The Owner's manual for the 280 Series Bushhogs do not mention the model #1287 or a 1000 rpm 287 at all.

ETA2: Sent an e-mail to Bushhog asking for clarification.

 

[LD1]

Ask the owner of the bushhog (if you arent close enough to go look) to spin the input shaft and see how many times the blades go around per one revolution.

Being a 7' cutter is gonna make it even worse. Because it likely means an even lower ratio since a 7' dont need as many RPM's to achieve ~15000fpm blade speed. Pile that on top of 1000rpm....

IF he spins the input and says the blades only went around half a turn or 3/4.....it certainly is a 1000rpm box.

"Hopefully" someone just threw a 1000 shaft on it so they could run it behind a BIG tractor at ~1/2 RPM.

 

[FTG-05]

Good news and bad news:

Good news is that someone did throw a 1000 prm shaft on it; it's a 540 rpm gearbox.

The bad news is that it's already sold.

Back to the drawing board.

The better news: Thanks to LD1 I now know to not *assume* all rotary cutters are 540 rpm cutters. I can't imagine the trouble I would have been in if I had went to all the trouble of finding, driving and buying a 1000 rpm cutter without knowing it, then ending up with a useless cutter. My thanks to LD1 - again!