M7060 something went SNAP!

[petrel]

Was hung up and walking the tractor out with the bucket; let out on the clutch and something went SNAP in the rear end! Now only front drive works. Left rear wheel will only turn when diff lock is engaged.

Called the dealer and they said it was probably a broken axle! If my new $30k tractor with 28 hours on it broke an axle getting out of a hole, I'm finding it a new home!

Somebody please tell me it is just a bent linkage or something else I can crawl under there and remedy. Thanks

 

[Fordtech86]

Sure sounds like a broken axle, in an open rear end it will spin the wheel with least resistance, that’s why the left one only turns with diff lock engaged.

 

[CobraTom]

Jack the rear of the tractor up and have someone apply the brakes. If you can turn the right side by hand, you have a broken axle shaft, if not its a reduction drive or a bevel gear.

Most likley though it is a axe shaft, they are intended to be the weakest point in the chain.

 

[petrel]

Thank you for your replies.

Is this a common occurrence? I grew up on a farm. Got tractors into some pretty bad spots, even used them for things we shouldn't have, but never broke an axle. Hard to believe the axle would break just trying to get unstuck!

 

[Tx Jim]

Welcome to OTT
Although still not a good thing I would come nearer thinking a pinion shaft or gear broke in differential before axle broke.

 

[lugbolt]

One would think based on how much these things cost that they'd be indestructible, but alas, NOTHING is.

 

[CobraTom]

Welcome to OTT
Although still not a good thing I would come nearer thinking a pinion shaft or gear broke in differential before axle broke.

There is another reduction drive in the axles shaft assembly, so the load on the pinion shaft and gears in the differential is actually quite low. The biggest stress is on the axle shaft or reduction drive.

OP, any chance your rear tires have weights on them or are loaded?

 

[petrel]

One would think based on how much these things cost that they'd be indestructible, but alas, NOTHING is.

Not indestructible, but rugged enough to claw its way out of a hole without damage!

 

[petrel]

There is another reduction drive in the axles shaft assembly, so the load on the pinion shaft and gears in the differential is actually quite low. The biggest stress is on the axle shaft or reduction drive.

OP, any chance your rear tires have weights on them or are loaded?

they are fluid filled

 

[edritchey]

Is this a new machine under warranty financed with KTAC insurance on it?

 

[petrel]

Is this a new machine under warranty financed with KTAC insurance on it?

New. About 28 hrs on it. No financing.

 

[CobraTom]

they are fluid filled

So this is where you most likely would not get the part covered under warranty. I am not sure how Kubota USA words their warranty agreement, but they may not honor the warranty because the tires are fluid filled, It would be something you would need to discuss with your service department.

Fluid filled tires put a lot of pressure on axles if they are rotating freely at speed and abruptly get stopped by traction. Without some form of clutching, or gradual slow down something has to give. It simply isnt designed for that kind of traction loss.

 

[rbargeron]

Cast iron wheel weights add rotational inertia and dead weight. Fluid ballast adds weight but does not add rotational inertia - the fluid is free to slosh when the wheel turns.

On why it maybe broke, the short stub axle has splines at the inner end. Axle splines are usually case hardened (only the outside surfaces are hardened) leaving the inner part and the wheel flange ductile and twist-tolerant. Case depth is time-dependent and the part can easily get through-hardened by overdoing it. I've seen Ford axles snapped off at the splines like they were made of ice. Dick B

 

[CobraTom]

Cast iron wheel weights add rotational inertia and dead weight. Fluid ballast adds weight but does not add rotational inertia - the fluid is free to slosh when the wheel turns.

On why it maybe broke, the short stub axle has splines at the inner end. Axle splines are usually case hardened (only the outside surfaces are hardened) leaving the inner part and the wheel flange ductile and twist-tolerant. Case depth is time-dependent and the part can easily get through-hardened by overdoing it. I've seen Ford axles snapped off at the splines like they were made of ice. Dick B

I fully agree with you at normal speeds, however if the single wheel is the only one without traction and runs at speed centrifugal force could force the water against the tire and add to rotational inertia.

 

[SidecarFlip]

Cast iron wheel weights add rotational inertia and dead weight. Fluid ballast adds weight but does not add rotational inertia - the fluid is free to slosh when the wheel turns.

On why it maybe broke, the short stub axle has splines at the inner end. Axle splines are usually case hardened (only the outside surfaces are hardened) leaving the inner part and the wheel flange ductile and twist-tolerant. Case depth is time-dependent and the part can easily get through-hardened by overdoing it. I've seen Ford axles snapped off at the splines like they were made of ice. Dick B

exactly correct. Have no idea how the warranty reads but, Kubota supplied cast weights as an option for the rears (I have them on the 9 and the 105 and they add appreciable weight, I believe around 500 pounds each side. Never been a fan of filled tires at all. Back in the day with CaCl, if you had a tire failure in the field, it was a guaranteed bare spot for a few years. CaCl don't promote crop growth.

Either the axle snapped or he has outboard planetary issues. Not hard to pull the outer axle case and look really. Usual procedure for heat treating axles is induction hardening and normalizing and today it's all CNC controlled. If the axles is wonky, his isn't the only one but he found out the hard way (if indeed that is the case. Only way to be sure is pull the outer axle case and look.

 

[edritchey]

Well I hope then what ever let go is covered under warranty or insurance if you had any coverage on it.

New. About 28 hrs on it. No financing.

 

[Jchonline]

So this is where you most likely would not get the part covered under warranty. I am not sure how Kubota USA words their warranty agreement, but they may not honor the warranty because the tires are fluid filled, It would be something you would need to discuss with your service department.

Fluid filled tires put a lot of pressure on axles if they are rotating freely at speed and abruptly get stopped by traction. Without some form of clutching, or gradual slow down something has to give. It simply isnt designed for that kind of traction loss.

Owners manuals (at least the newer ones) specifically recommend tire ballast for certain tasks, and in fact give recommendations on how to fluid fill them. I dont think he will have an issue with having it warrantied.

 

[rbargeron]

I fully agree with you at normal speeds, however if the single wheel is the only one without traction and runs at speed centrifugal force could force the water against the tire and add to rotational inertia.

It's a physical fact that no matter how hard centrifugal force pushes it outward, the water still develops no shear force at the tire's inner surface. Even if the tire rotation suddenly stops, the water is free to keep rotating, and doesn't add to axle loading.

 

[JohnDB]

It's a physical fact that no matter how hard centrifugal force pushes it outward, the water still develops no shear force at the tire's inner surface. Even if the tire rotation suddenly stops, the water is free to keep rotating, and doesn't add to axle loading.

I agree

 

[petrel]

I would be very disappointed if the filled tires caused a warranty issue. They were an option offered and installed by the Kubota dealer. I think they actually recommended it, since the tractor is equipped with a loader.

My thanks to all for your help while I try to understand this. I have about a 5th grader's understanding of the physics involved. Therefore, I will cling to my basic idea that a doggone tractor should not break itself while attempting to claw out of a hole.

I did an after hours service drop off at my dealer last night. Hopefully, I will have some new information in a week or so.