Replacing output shaft on Rhino brush hog

[sgtboz]

Well, I sheared off the output shaft on my Rhino 172. I didn't even hit anything of substance, I think it'd just given all it had to give over the years.


I started the swap yesterday but ran into a point where I figured some advice by you guys would save me a LOT of heartache in taking wrong paths to the solution.

Here's the new shaft (~$250+...ouch!)


And here's a labeled picture of the Comer gear box. Will the output shaft come out of the top of the gear box? I've replaced a bottom seal before, mistakenly disassembling the gear box before realizing I could replace the seal only from the bottom...doh! But this gear box seems a little trickier to remove the top horizontal shaft. Does anyone have an idea the sequence with which I'll remove things to get to the output shaft? Will I have to tap out/press back in any bearings?

 

[In Utopia]

If you can, I'd return the shaft, and instead of replacing just the shaft you can buy a whole new gearbox for $250 or a little less.
It's not necessary to buy the same brand you're replacing. Most gearboxes of equal HP rating are the same dimension wise.

 

[sgtboz]

That thought did cross my mind but I couldn't find a reasonably equivalent 60hp rated gear box for anything close to the price of the output shaft. If you can point me to a source, I'm sure I can return the shaft but take the hit on a re-stocking fee and lotso shipping charges. The cost for the OE gear box is ~$460 plus shipping. OUCH!

While I don't have much extra free time for such tasks as this, I would like the experience of having changed out a shaft and taken on this kind of work.

My hope is that I can get some guidance here on the forum.

 

[sgtboz]

This is clearly not a topic of broad interest (or possibly knowledge) but to make matters worse, the seal/shim kit on the input shaft is another $150. GOOD GRIEF! It's hard to remove those without damaging them but I can sure you I'll be EXTREMELY careful.

Can anyone give ANY advice (or even condolences) perhaps?

 

[Russell King]

I have no expertise on the gear box but it looks like you have the information in the paper that has the parts list on it.

I can only guess that there is a snap ring holding the gear on the input shaft. Remove it and then the shaft may go out the seal end
Then output shaft can go in

Good luck


Sent from my iPad using Tapatalk

 

[sgtboz]

I'm not sure if it'd be helpful to start another post some day but who knows when the information might prove useful to someone else.

Removal of rear seal

Fixed that 'dent' with a pair of pliers.

Removed snap ring and shims. Be WARNED - if you mess it up, the replacement seal/shim kit is very expensive - ~$150!!!! Unbelievable:

Tapped out input shaft from the front side with a small hammer

Removed input bearing and bevel gear

This gave access to the top of the output shaft castle nut

These little shims are everywhere and easy to lose since they sometimes get stuck on the back of whatever they are touching!

Output shaft bevel gear and bearings. You can see the output shaft in the bottom of the gear box.

Here's a picture of the input shaft seal in case anyone ever wonders what that looks like before they replace one!

And this is as far as I got before the bride said supper was ready and my date with the gear box was over for the day.

Further updates to come soon.

 

[In Utopia]

Several sources, google is your friend.

http://www.ebay.com/bhp/rotary-cutter-gear-box
http://www.agrisupply.com/rotary-mower-parts-gearboxes/c/1900059/

 

[sgtboz]

Thanks, Utopia. (I googled your town, by the way.)

I couldn't find an equivalent rated gearbox for less than the output shaft but at this point, that's neither here nor there. I'm 90% into the job and learning lots in the process. Hopefully it'll help someone else someday in the same situation.

 

[sgtboz]

Aaaaaand....here's this one. Dang! http://www.agrisupply.com/gearbox-rw-610-spline-input-shaft/p/87857/

Oh well, I would have had to build an adapter plate to get it to fit on my brush hog so all things considered, I'm probably on a reasonably right path. That's what we tell ourselves sometimes anyway.

 

[William1]

Kudos for forging ahead. Make sure you check gear lash with bluing. Shims wear, gears do not sit on a new shaft exactly where they did on an old one.

 

[Ramos]

As already mentioned, you will most likely need a shim kit or individual shims. They are needed to adjust the end-play of the shaft. New shaft and old shaft will not be machined exactly the same. Of course, this is not a NASA gearbox. Meaning it needs to be close to spec but not necessarily perfect.

 

[sgtboz]

Excellent point, William and Ramos! I hadn't thought about that but it makes perfect sense. Thanks for taking time to weigh in. I'll add the rest of the pics once I get the job done.

 

[sgtboz]

The next steps required getting under the brush hog and then I eventually just decided to removed the gearbox altogether. I used my L3800 to set the Rhino 172 up on a sturdy parts rack I have at the house.

Next off was the lower seal, snap ring, and washer.

Here is the output shaft after having been removed from the gear box. You can see the lower bearing in there. This thing is so low in the gearbox you can see why using only grease in this gearbox might be a recipe for disaster. The bearing had to be tapped off the broken shaft. It's a reasonably tight fit but nothing requiring a shop press.

Removing the bottom seal without messing it up seems like a near impossibility...as you can see here with this dang leak! The new one is scheduled to arrive on Friday but at least I don't have to take the whole thing apart to replace that bottom seal.