B26 TLB rear axle broken teeth

[Elmike]

Need help diagnosing what could be causing a broken teeth on gear , the failure is on the right side of the rear axle, picture attached

Same failure has happened 3 times same axle right side same gear, please help!

Thanks

Mike

 

[lsmurphy]

Looks to me like the pinion gear is riding high on the bull gear.

How are the bearings? Have you replaced the pinion gear bearing?

 

[Elmike]

Yes we replaced them and it fails again and again

 

[Elmike]

First time we replaced bearings 030 and 060, and failure appeared 3 months later same a broken teeth on same gear 040 , always right rear axle

 

[Elmike]

I just read the article below and it lead to the next question : Locking the differential and turning could lead to a damage like the one i'm talking about?

When to Use the Differential Lock
Because the differential system on your Kubota allows the rear tires to turn at different speeds, locking the differential should only be used when traveling in a straight line. If you lock the differential and then attempt to turn, you put extra strain on the differential lock, possibly leading to its or another component’s failure.

 

[skeets]

Is that what happened when it broke??

 

[BotaDriver]

It'd be nice to have more info about your machine (tires, etc) - What it's used for, how many operators, experience of the operators.... Does it happen when a certain task is performed, or noticed a short time after?

 

[Dan_R_42]

I just read the article below and it lead to the next question : Locking the differential and turning could lead to a damage like the one i'm talking about?

When to Use the Differential Lock
Because the differential system on your Kubota allows the rear tires to turn at different speeds, locking the differential should only be used when traveling in a straight line. If you lock the differential and then attempt to turn, you put extra strain on the differential lock, possibly leading to its or another component’s failure.

Seeing the damage in the photo, what you just posted above makes perfect sense. As BotaDriver posted, what function was being performed when the damage happened each time.

 

[Donystoy]

Just noticed in the photo that the contact wear in the top pinion gear teeth seems to be concentrated inboard close to the bearing and not evenly along the face of the gear teeth. This would result in all the force been placed on this end and it would appear that the tooth on the lower gear started to tear out at this same location. Any reason why these gears are not in perfect mesh and are out of alignment? Bearing wear on lower gear? Just a thought.

 

[kubotasam]

I think Ismurphy is on to it. You said you replaced the bearing on the axle shaft with the large gear. Did you check for any play in the bearings on the shaft that comes out of the differential housing with the little gear attached?
If there is any play in the bearing the gear teeth will climb each other and all the pressure is on the tips of the gear teeth. That is what breaks them off. They need to run with full side contact.

 

[BotaDriver]

I think Ismurphy is on to it. You said you replaced the bearing on the axle shaft with the large gear. Did you check for any play in the bearings on the shaft that comes out of the differential housing with the little gear attached?
If there is any play in the bearing the gear teeth will climb each other and all the pressure is on the tips of the gear teeth. That is what breaks them off. They need to run with full side contact.

Not just play in the bearings to be concerned with, but anything on the backside of the shaft that would allow any type of play in it. The first time it happened the missing chunk could have came back through the gears and caused enough play that the last 2 times that it's happened, is due to damage from the first time.

Not sure of the cost of replacing the bearings and any type of collars on the shafts. I'd weigh the cost of replacing everything to do with those 2 gears (bearings, collars, etc...) vs having to replace the gear this time and 2 more. Seems like until the issue is fixed it will just keep happening.

The details of how / why really need to be considered here.

 

[lsmurphy]

I turn with the diff lock on.

If true then we all would be breaking teeth all the time......on the left side and right side.

 

[Bluegill]

After the second break, I would have replace the axle shaft & all bearings associated.

Are you using the brakes to turn sharp? That can put extra stress on this area.

 

[Elmike]

We haven't change bearing 090 , the one inside the differencial housing , do you think this could be the problem?

 

[lsmurphy]

We haven't change bearing 090 , the one inside the differencial housing , do you think this could be the problem?

Yes, the small gear is climbing the large one.

 

[Donystoy]

Tried to go back and read the entire thread to verify this but I was wondering if the two gears were not replaced as a set you could just be experiencing the effect of having the original pinion wear not meshing correctly with the new bull gear. It is always recommended that when changing out a broken gear that the mating gear be also replaced. The mating surface contact area is then verified by spraying a paint onto the gears and then spinning by hand. I use to use what they called blueing to verify proper center mating contact of gears.

 

[lsmurphy]

Tried to go back and read the entire thread to verify this but I was wondering if the two gears were not replaced as a set you could just be experiencing the effect of having the original pinion wear not meshing correctly with the new bull gear. It is always recommended that when changing out a broken gear that the mating gear be also replaced. The mating surface contact area is then verified by spraying a paint onto the gears and then spinning by hand. I use to use what they called blueing to verify proper center mating contact of gears.

He's not setting up a differential, there is no adjustment.

They either mesh or they don't.

 

[Donystoy]

He's not setting up a differential, there is no adjustment.

They either mesh or they don't.

I am very well aware that this is not a differential and there is no adjustment but if the OP finds no other reasons (sloppy bearings etc.) for this obvious improper contact area on the teeth I am only suggesting other possible areas to explore. I would never install a new gear against an existing worn one without checking to make certain of the contact area. There is nothing to guarantee that the original gears wore evenly.

These gears are transferring a lot of power and in my opinion "just meshing" is not good enough.

Maybe I am just too fussy but I like to do a job once.

 

[BotaDriver]

I turn with the diff lock on.

If true then we all would be breaking teeth all the time......on the left side and right side.

Yeah, hard on the diff lock, but it's only ever needed on the soft stuff. I turn and get un-stuck w/ it several times a week.

 

[Elmike]

So reading all the advices we better change bearing balls 030 and 060, collar 050, gear 040, shaft 150 that goes into the differential and both bearings 160 and 100 on the differential housing.

Do you think we should change shaft rear axle 010?

Why we always got failure on the righ side axle?