Woods Brush Hog Gearbox keeps blowing open

[L3010Ken]

The gearbox is a cast unit with a front bearing held in the casting and the rear bearing held by a stamped sheet metal housing that is held in place on the back of the casting with a large snap ring.

If I hit a big rock, the snap ring pops out of its groove, the stamped rear cover of the gearbox goes flying and all my gear oil flys out and makes a mess on the back of the deck. If I don't hit anything, it holds together fine and doesn't leak - although it seems like it is happening with smaller and smaller impacts. I have a slip clutch - and I know it works (ran over a crib mattress someone had tossed out onto one of my fields and the clutch worked perfect).

This has happend about 5 times now and I am looking for fixes. Has anyone else dealt with this? Looks like the recess groove that the snap ring fits in was not machined deep enough or concentric with the bore of the gearbox.

 

[JerryG]

Make a girdle out of flat steel and all thread.

 

[Soundguy]

Inspect the bearing.. when installed does the shaft have any front/back play? if so bearing is bad.. or housing is deformed/shaft bearing surface is worn.

Inspect the shaft where the split ring rides.. is there a chamfer or other damage or wear showing anywhere in the grove? If yes.. then the ring will continue to pop out. Same witht he ring. if it is stretched out of tolerance. or rounding out.. it will ride out of hte groove easier.

The saddle idea will work, kinf of like a big metal bandaid.. doesn't correct the problem.. but does prevent the outcome.

Soundguy

 

[JerryG]

<font color="blue">The saddle idea will work, kinf of like a big metal bandaid.. doesn't correct the problem.. but does prevent the outcome. </font>
I should have put a smilie face. I don't joke on here very often. It would of course be a last resort. There is a reason that it is knocking the ends out. Either it is machined wrong or assembled wrong or the PTO shaft is being jambed into it.

 

[RickB]

Landpride and Bush Hog have used a gearbox that sounds identical to the one you describe. Haven't seen the Woods, but the LP and BH are identical except for the paint. They are junk. BH has a more robust replacement with the same input shaft, mount, output shaft and ratio that retailed for about $200 last year. Our shop won't repair the style with the sheetmetal rear cover unless the customer demands it. Your snap ring or snapring groove is probably at fault as you suspect. Stamped snaprings need to be installed right side out as well.

 

[JerryG]

Rick,
From what you have seen, has the snap ring groove not been machined deep enough?

 

[L3010Ken]

I took a better look at it this morning. The snap ring groove that is machined in the cast housing doesn't appear deep enough. Bearings are still tight very little backlash in the box so I don't feel like I need to replace it.

Would be a major pain to disassemble an re-machine properly.

I think I'll replace the snap ring with a spiral retaining ring. I started using these on several applications in the last few years and they seem to work better.

http://www.smalley.com/ring_detail.asp

If it continues to blow apart - I'll post pictures of the girdle.

 

[RickB]

Not sure. I do think relying on such a large diameter piece of sheetmetal to support a small diameter bearing is a lousy idea. Cheap to build, but flexing of the plate due to loading from the gears will help the snap ring to 'walk' out of its groove. Haven't seen this particular gearbox on new machines in several year. I'm betting there is a reason.

 

[JerryG]

I don't know if it would work or not and have never tried it but a piston ring cleaner / cutter might be able to increase the depth of the groove enough to help keep the ring in place. You might have to use more that one blade, but it is worth a try.

 

[JerryG]

Rick, thanks for the reply. I wasn't aware that the metal cover actually had to help retain the bearing. If that is the case, maybe the cover also needs to reinforced. Sounds like a poor design to save a few cents.