OT-New John Deere tractor with broken axle - Metalurgy Question

[Modelman]

Hu is right. I've always heard the absolute worst thing you can do for your driveline is let the wheels "hop" when they don't have traction. It's a constant loading and immediate unloading of the drive line. Tractors don't do it so bad since they have deep groove tires and really low gear ratios. But semis can and will.

If the rear axles start to hop, you need a tow.

Boy, does THAT bring back memories. When I was a kid, I had this brilliant idea that since redi-mix trucks sit idle all winter when little construction is going on, the company should rent them out as plow trucks. I proposed this to a family friend who worked for one of the redi-mix outfits. His reply was they had tried it one year in the fifties, and the next spring had a rash of broken axles when they started delivering concrete. Best they could figure is that when the empty trucks stated hopping while bucking snow, they started fractures in the axles, and getting stuck on the job sites in the spring finished them off.

Dennis

 

[L Vanice]

Those pictures looked very familiar. In the 1960's, I worked in the axle laboratory of International Truck's engineering department. The Fort Wayne IHC factory across the street had a forge shop and made heavy truck axles, among other components. The factory had its own metallurgy lab and test lab, but engineering also had a metallurgy lab and lots of testing labs for all parts of the trucks.

How to break an axle:

We had a continuously operated (two or three shifts) axle shaft fatigue testing lab. It was based upon a large Prony brake chassis dynamometer. A bare heavy truck chassis with a gas engine, manual transmission and single rear axle was tied down to the floor. Air cylinders were arranged for remote control of engine speed, clutch operation and dynamometer load. The rear tires sat on large steel rollers that had adjustable brakes applied to them. A Toledo scale was attached to an arm on the roll brake to indicate resistance force. A strip chart recorder kept a record of the torsion loads from strain gages on the test axle shafts versus time. The routine was that the engine would be revved up to a set RPM and the clutch would be suddenly engaged. There was a shock load on the axle rather similar to what you would get dumping the clutch with the engine revved while the wheels were stuck in sand*. It was very noisey. We had a display of failed axle shafts to illustrate the various failure modes, which were all fatigue failures, but not always in the same location on the shaft. Our favorite was the shaft that had broken into three pieces from two simultaneous fractures some distance apart. I don't recall the normal number of cycles to failure for the different models of axle, but they stood up to an awful lot of abuse, probably in the thousands of cycles.

You have to see it to believe it? I just happen to have a 1969 photo of the engineering Prony brake dynamometer. The broken parts were on a cabinet behind where the photographer stood, so you have to take my word for the double break.

Larry

*I have a faint memory that an old timer said that burying the rear tires of an actual truck in sand and popping the clutch was exactly how the tests were run before the first indoor dynamometer was built. The engineering building, with the Prony brake, was built about 1952.

 

[lars66]

Those pictures looked very familiar. In the 1960's, I worked in the axle laboratory of International Truck's engineering department. The Fort Wayne IHC factory across the street had a forge shop and made heavy truck axles, among other components. The factory had its own metallurgy lab and test lab, but engineering also had a metallurgy lab and lots of testing labs for all parts of the trucks.

How to break an axle:

We had a continuously operated (two or three shifts) axle shaft fatigue testing lab. It was based upon a large Prony brake chassis dynamometer. A bare heavy truck chassis with a gas engine, manual transmission and single rear axle was tied down to the floor. Air cylinders were arranged for remote control of engine speed, clutch operation and dynamometer load. The rear tires sat on large steel rollers that had adjustable brakes applied to them. A Toledo scale was attached to an arm on the roll brake to indicate resistance force. A strip chart recorder kept a record of the torsion loads from strain gages on the test axle shafts versus time. The routine was that the engine would be revved up to a set RPM and the clutch would be suddenly engaged. There was a shock load on the axle rather similar to what you would get dumping the clutch with the engine revved while the wheels were stuck in sand*. It was very noisey. We had a display of failed axle shafts to illustrate the various failure modes, which were all fatigue failures, but not always in the same location on the shaft. Our favorite was the shaft that had broken into three pieces from two simultaneous fractures some distance apart. I don't recall the normal number of cycles to failure for the different models of axle, but they stood up to an awful lot of abuse, probably in the thousands of cycles.

Larry

*I have a faint memory that an old timer said that burying the rear tires of an actual truck in sand and popping the clutch was exactly how the tests were run before the first indoor dynamometer was built. The engineering building, with the Prony brake, was built about 1952.

I can tell you an International truck axel in them years was only good for 2 or 3 wheel hops backing up the ramp on the gravel stockpile then I was changing an axel. One job I was loader operator loading then jump in co. pickup with spare axels rolling around in pickup box and run to stockpile to be dozer operator and axel changer.

 

[FredC]

A couple of more things to add, I checked the manual on my small IH tractor (55 HP). It said to reduce tractor speed before engaging the diferential lock. Not the same tractor but it is not an insane thing to do at lower speeds.
The splines are 2 1/4 across the outside. The tapped hole is more like 5/8. The shaft till it gets to the hub bearing is about 2 1/2 inches. The whole shaft is about 20 inches long.
I looked at the axle again and the splines were twisted about one full notch. Quite a bit of torque was applied before it broke.
I guess the mechanic and I expect tractors to really stand up to adverse conditions. On my big tractor I have stalled the engine in second gear when the V ripper went down to the frame, 32 inch blades fully engaged with a 535 cubic inch turbo charged engine. With the same tractor I pulled a truck weighing 391,000 pounds up a hill in first gear. Peeled up the pavement the whole way.
Back to the broken axle, if nothing stands out as wrong with the heat treatment and grain structure where it broke, then this was operator caused or the axle is undersized for the expected conditions. Since this same tractor is supposed to be able to handle an engine with double the power, I am leaning towards the operator did something drastic.

 

[BridgeportinD2]

Look the the SN tag. If it's a 60hp machine, there's a very high chance that it's made in a country that starts with I and ends with A. A recent 5000 series or offshoot of. Do I trust or like them? NO.

Shoddy and very poor are how I'd rate them.

I'm not really "in the loop" anymore, but the orginal Dubuque tractors of that size have been sourced from plants in Germany with French engines or from Mexico as a total unit for a couple of decades.

Waterloo didn't build anything in that HP range since the 2510 or 2520.

After having wrenched on Deeres, made parts for Deere, still making tools for Deere, and a fair amount of time running their tractors and other equipment I have no bad blood with Waterloo, Dubuque, Mannheim, or Monterrey.

The 'starts with an I and ends with and A' series of units suck.

I don't trust their material, machine work, heat treat, QC. The product seems hit-and-miss okay or eats itself while it runs kind of thing.

I hope the dealer and Deere own up to this. You don't deserve the problems of the failure- Deere does.

 

[n2zon]

My experience has been that John Deere stands behind their products. *Write* them, tell them what happened, what you expected from their product, and what you want. Worked for me.

John

 

[gbent]

It's a cheap ass design.
...
I'm not sure why tractors can't figure out how to use full floating axles. Trucks have been doing it for decades.

Yes, its cheap. That market segment has a lot of competition and proper construction wouldn't allow the premium Deere requires for their green paint.

Its pretty difficult to make full floating axles that have the adjustable track width required by row crop ag tractors.

I don't understand why the dealer is dragging his heels if the tractor is under warranty. Mother Deere pays for the work.

 

[ewlsey]

Its pretty difficult to make full floating axles that have the adjustable track width required by row crop ag tractors.

Usually, only larger row crop tractors have adjustable width via the actual axle. The smaller units use adjustments between the outer rims and centers.

 

[metalmaster10]

Neighbor broke an axle last year on his 325 hp tractor.... That was an impressive sight. I have never seen an axle the size of a cantaloup sheared off before...

 

[dkmc]

I wonder what kind of FEET-tons of torque is produced to DOO that??

 

[Ziggy2]

Other possibility is he engaged the diff. lock with one wheel already spinning.
Depending on the tractor model??, this is not that hard to do.
David

Application of the associated steering brake can also trigger this scenario, though not quite as severely as engage the differential lock.

Either way it is a huge transfer of enertia into the non-rotating drive wheel assembly.

 

[Barron]

I believe that tractor axle was defective from the factory. I have spent many thousands of hours in a tractor seat (10 more hours today) over the last 40 years, tractors ranging from 9hp Farmall Cub to a 130hp International 1086, and almost everything in between. I've been hung up countless times, spun the wheels, "hopped" the wheels, popped the clutches, etc. and in all those years, I've broken two axles. The first was a 25 hp 1952 Minnepolis Moline. I backed into a round bale, and when I raised the lift to pick up the bale, the axle broke. This happened in the mid 80's. The second was a Deutz 4006 (40 hp), it broke while mowing hay. Not spinning, hopping, or over torquing, just a routine activity for a tractor. Both of these, I'd credit to years and thousands of hours of use and fatigue.

HuFlungDung wrote,

In a farm tractor, the front wheels may begin to lift off the ground if the tire is not rotating, and naturally, you'd release the clutch in a panic so it stops rearing up And that is when the pent up torque releases and unwinds the axle.

This action will not twist a normal tractor axle. You immediately reduce/relieve the torque on the axle when you depress the clutch, though you might break the front end out when it hits the ground!

sticks wrote,

Diff lock pedal was/is on the left side of the op platform of my 1520 and 5210 JDs. Best to be out of gear or clutch-in when activated. Depends a little on how far each wheel was 'buried' however deep once engaged, too. Consider the gear ratio (engine to wheels) and torque multiplication therein. 65hp means a lot of torque applied to an axle turning 28" or larger rims by planetary reduction and in a lower gear. ("something's gotta give" ..)

Differential locks are located on the right side, at least on every tractor I have ever owned or driven, so that you can clutch with your left foot, depress the differential lock with your right heel, and then release the clutch. I agree that one should NEVER depress the diff lock while a wheel is spinning. Doing so will usually shear the pin that locks the differential (ask me how I know), but is unlikely to break an axle, in my humble opinion.

 

[MarkL]

John...I'm a metallurgist and I can tell you that the shaft broke under torque while spinning and hopping the tires due to the "ratcheting" of the failed surface. This failure is common with intermittent sever overloads in shafts. Once a small crack starts , it grows as the cross sectional area gets smaller and thus higher tensile strengths exceed the parts design. On a machine with that little hours, dealer should repair and warranty. Regards, Mark L.

 

[Speedie]

That looks like a very shallow heat treat.

 

[FredC]

I just talked to the mechanic and the tractor is a 4 WD 5065E. The shattered bearing race does say Timken India.
The John Deere dealership that nixed the warrantee on this was being sold at the time. So the previous owner of the dealership may have been looking out for himself only.
The JD mechanic that nixed the deal said the owner had tied fence posts/logs to the wheel that fell off, but there is no evidence of that.
Sand was mentioned as a contributing factor, I mentioned that to the mechanic and he agreed that it would be worse than the slick mud I am used to getting stuck in. It took almost a month for the spot to dry up so they could get the tractor out.
We just do so many abusive things to these tractors with no bad consequences that it is surprising to see one die so soon. On my small tractor I have an attachment for pulling trees/brush. I back up to a tree clamp on to it and lift up till the front wheels just barely lift off the ground then push and pull on the tree till the side roots are loosened, then pull the tap root out. Lifting the front wheels off like that gives me maximum traction when pushing and pulling, but also puts maximum load on the axles. Till now I never worried about breaking them.
On the big tractor when ripping or plowing I drive at a fence till the front wheel weights are a couple of feet from the fence, lift the implement, turn the wheel, and hit the turn brake almost at the same time. I have worried about the shock to the drive line in hitting the turn brake so hard so I try to stage it by pushing slightly to take the slack out of the gears before really getting on it.
Thanks for all the help, you have given us a lot to think about. If anyone else can add to this it would be appreciated and I will let you know if JD corporate does anything. Maybe the new owner of the dealership will change their position.

 

[DMF_TomB]

i have seen where parts were heated to be shrunk on that the heating was at too high a temp and affected the heat treatment.
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a company i know had problems with electric motors magnets loosing magnetism. they traced it to assembly and putting a part in a oven with not good enough temperature control. they heat shrunk the parts together but unfortunately damaged the magnetic parts in the process
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i would try to test the broken parts heat treatment.

 

[FredC]

That looks like a very shallow heat treat.

Speedie, the surface on the splines is very hard. The steel deeper is tough but not so hard. I would have guessed case hardened steel but someone else suggested selective induction hardening. The main part of the shaft between the ground areas is only moderately hard. My only hardness tester is a new file. Not having seen very many tractor axles, I could not say if this was done on purpose or a manufacturing defect.

 

[DMF_TomB]

as companies out source purchasing metal i have seen cut to length raw pieces of metal not clearly identified as to metal type. so somebody thinks they got 4140 and they instead have 1018 steel
.
i prefer metal to have alloy type stamped on it but often it is written with a marker. it is tough to figure out what you got without expensive equipment.
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i am just saying big companies often rely on other companies to supply cut to length pieces of metal. often there is too high a level of trust that a minimum wage worker in a small metal supply company is doing their job correctly. kind of important to get a part made of the correct metal alloy. and this is not a problem with any country this is a world wide problem.
.
even SpaceX lost a Rocket because a bracket or strut failed when it was suppose to be able to take a much higher load. my guess is they will do more part testing before rocket assembly now and not trust suppliers as much