Crack in Bush Hog Gearbox

[Kyle_in_Tex]

The manufacturer is backing it. Just downtime, and expense of time & transport to the dealer. Bush Hog has been very good about it AND admitting they have had some of these failures and do not know why. Say their supplier does not understand the cause either. No idea where it was made but has the Bush Hog name in raised letters on the gearbox.

I'd just like to hear if others have this issue and where their gearbox cracks were. Curious. Hopefully the replacement will be durable.

I'm glad to hear this. That is what I was hoping for.

 

[Xfaxman]

JWR, we need an update please.

 

[JWR]

JWR, we need an update please.

OK, here's an update: BushHog responded to my email, said they would back it. I took the hog to the dealer where I bought it, the company shipped a replacement gearbox to him and he put it on. I have put about 5 or 6 hours on it since the gearbox was replaced and had no problems. It took a while to get all this done but I am only able to work the equipment one week a month so it was not a big deal. I would still like to hear from others who have had the same issue (e.g. a hairline crack in the BushHog gearbox an inch or so above the bolt pattern on the deck, leaking lubricant, no apparent cause.) I have had no feedback from anyone with the same problem but Bush Hog said they had some of these and I was not the only one.

 

[Xfaxman]

Thanks, glad to know they replaced it. :thumbsup:

 

[Kyle_in_Tex]

That's good news.

 

[RickB]

Manufacturer honors warranty, replaces faulty gearbox. Acknowledges this failure to be a known problem.

Gearbox COO= China. Any further analysis necessary?

 

[SPYDERLK]

Manufacturer honors warranty, replaces faulty gearbox. Acknowledges this failure to be a known problem.

Gearbox COO= China. Any further analysis necessary?

Cause = Process variability. :confused3:

 

[RickB]

Cause = Process variability. :confused3:

Undoubtedly.

 

[basicequipment]

JWR, I know this is an old thread. Just wanted to let you know that my BH296 cutter has failed in the same place and in the same fashion. I own a fab shop so I have already repaired the casting with nickel rods but I can tell you and Bush Hog exactly why it failed...... Although, from the outside, the casting looks very beefy and thick, the lower side wall of the box is less than 1/8" thick in some places. Way to thin for this application!!! As you know, the base mounting flange on the gearbox is about 7/8" thick then it immediately transitions to 1/8" thick up the sides. When welding a crack in cast iron it is standard practice to drill a hole at each end of a crack to help prevent the crack from continuing on after the original crack is repaired. I was expecting the sidewall to be at least a 1/4" to 3/8" thick when drilling but the bit unexpectedly punched right through the side with no trouble. I doubt they will make my gearbox good after 4 years but I bought a Bush Hog brand cutter simply because I expected the best quality from them. The other posters above are correct about these gearboxes being made in China. My gearbox has a Bush Hog ID tag on it that clearly says MADE IN CHINA. I had not really considered contacting them until I read your thread but now I think I will since it is a known problem, especially after getting a quote of $1200 from the dealer for a replacement. Now I wish I had waited about welding up the crack. I'm sure it is just a matter of time before it cracks again somewhere else.

 

[CalG]

So

Looking at the photo of the location of the crack, The defect is in the casting thickness at the intersection of the gear box and the mounting flange.

The flange is the member that takes the torque reaction from the transmitted power. It would be interesting to know if the crack appeared on the drive Tension side, or the drive compression side. That might give an idea as to the nature of the load that caused the failure. Shock load or other.

The design weakness is not enough material at that corner. As a sand cast part, it would be easy enough to shave off a little from the mold to add thickness. But since the supplier is "over there", That's going to be like pushing a chain up a hill.

Still, It's good to know that the internals of the gear box can stand the beatings, while the case can not. I have never heard of a reputable maker not standing behind the box that the dear parts are housed in,

Think of it, If you had not noticed the lube weeping out, and run the box dry. Seizing the bearings and burning up the shafts etc. The defect would go unannounced, and you would be buying the replacement box.

Good for you for PAYING ATTENTION! ;-)

eta
I should have read "basicequipment's post. Shame on me.... but it is interesting what one picture will show. ;-)