JD 2520 Snapped Axle

[RoyJackson]

Holy.... Talk about meeting the judges, juries, and executioners all in one thread.... Without seeing it firsthand who the heck knows what happened..

Being both a pilot and mechanical engineer, It is hard to point a finger when you are simply looking at pictures.....

All true...but this is an internet forum, after all...

 

[PapaPerk]

I'm not a metallurgist (my field is Quality Assurance/Engineering), but I think you're simplifying things a bit too much for that blanket statement. Fatigue strength depends on the alloy and, more importantly, the design.
If there had been a trend in failures of this design and material, you'd have a point...but to the best of my knowledge, there hasn't been a lot of failures (more then likely, we would have read about it on TBN).

BTW, I think most ferrous castings on tractors are cast iron, not cast steel.

Most castings on tractors and other equipment are ductile iron. Not cast iron. Cast iron is far too weak for stressed components. If parts are under high loads, then the parts are forged.

You are correct. Fatigue strength depends on material. Steel has a much higher fatigue strength (general alloy) than aluminum (general alloy).... approximately 2 times.

Obviously something caused the failure. If the casting failed... the part either had a crack (defect) from the factory or operation loading exceeded design specs.

 

[PapaPerk]

Holy.... Talk about meeting the judges, juries, and executioners all in one thread.... Without seeing it firsthand who the heck knows what happened..

Being both a pilot and mechanical engineer, It is hard to point a finger when you are simply looking at pictures.....

That's what forums are for.... discussion and hypothesizing. So don't take it too seriously.

 

[Interlaux]

I'll repeat, split your brakes and set your cruise control and try and stop with one brake on damp soil. It will leave a skid mark just like that one. You don't even need to be going very fast to do it. Unless you creep around at idle in low gear all the time on a tractor, this is what happens when a tire locks up. Not abuse.

cant wait to try it. Loved to watch the FIL lockup one side on the 566 fiat and swing around a turn. Never tried it on the 4610.

good input on this one slow:thumbsup:

 

[OzGrasshopper]

Hi All , i think the poor chap posted this accident up to see if anyone had any idea of what might have happened....as result a lot of folk have given fair input, and if i were him i'd sift through it all to be better armed with a few reasoned questions to put to JD dealer - IMO thats better than just say "hey it broke."
my friend has one of these machines, rotaryhoe, blade work etc in tough rock country and had no trouble, but on a very bad day when perhaps things line up wrong it can happen. i've seen severe seal damage to 60-80 hp tractors from bale netting, so that could well have momentarily hooked IF... that tyre was jammed from the back linkage, and IF the implement jolted for what ever reason, each event on its own probably would have been handled, but put 2 or 3 events happening just at the one time and bingo - snap. otherwise some casting imperfection could be the case - probably have better idea on that after the axles out.
regardless it was a sad day - i feel for u mate, it would be a dissappointment.
cheers OzG

 

[jenkinsph]

I'll repeat, split your brakes and set your cruise control and try and stop with one brake on damp soil. It will leave a skid mark just like that one. You don't even need to be going very fast to do it. Unless you creep around at idle in low gear all the time on a tractor, this is what happens when a tire locks up. Not abuse.

Hmmm I dont use my cruise and boxblade at the same time. I creep around when using my boxblade so I have enough time to react to the needed changes and settings.

 

[pdp11]

Although there has been a certain amount of judgement passed on the situation by those posting to this thread, I think it has been enlightening.

As an owner of a 2520, I have learned that there are really two 2520's (not counting the one from the 1960's). The 2520 that was made between 2006 and 2008 is different in a number of ways than the ones built from 2009 onward. This was a point of confusion for me when I was using forums such as this one to do research prior to buying mine. Reading postings from people complaining about the small alternator and the problems with lift arm to tire contact made me wonder if I was making the wrong choice of tractor, until I realized that Deere (Yanmar) had changed all that. I later discovered that they also have different engine models between those same years.

This owner's unfortunate experiences seem to make it clear why the lift arm design needed to be changed. If there is too much sway in the 3PH with either a heavy or heavily ground engaging implement attached, then the lift arm can be pulled into contact with the tire so as to stop it from turning. Because of the angles and torque involved, it puts too much stress on the final drive and damages it, eventually leading to failure.

 

[goldenwings]

I realize this may not be the place for this, but... What is the difference between the two engines. I have a 2006 model FWIW.

 

[slowzuki]

My comment to use cruise is based on owning an HST Kubota, my brake foot is my hst foot so I can't simulate locking up one tire without cruise. If you have a Deere, ignore. My Massey gear drive I would just step on one of the split brakes.

Hmmm I dont use my cruise and boxblade at the same time. I creep around when using my boxblade so I have enough time to react to the needed changes and settings.

 

[pdp11]

I realize this may not be the place for this, but... What is the difference between the two engines. I have a 2006 model FWIW.

They are similar and both are called 3TNV82A. The older one is a -MJK and the newer one is a -BMJK. I know the newer one has a different oil pump and uses glow plugs instead of an intake heater. I believe that it also has other differences, which may include meeting different emissions standards.

 

[dfkrug]

BTW, I think most ferrous castings on tractors are cast iron, not cast steel.

Why do you say that, Roy? Can you site a source?

I have tried for years to get more info from tractor makers on the cast
ferrous alloys they use. There are lots of grades of cast iron out there
(grey, white, malleable, ductile), and cast steels, too. Pretty much if you
get the carbon below about 2%, you have steel. Above 2%, cast iron.

I can tell you from my experience that the cast iron/steel used in my JDs
is quite soft and machinable. And clearly cast, not forged.

As for small sub-2000#-class CUTs, like the OP's JD, a number of them
use cast aluminum for structural elements, but I have found no current
CUTs in the 3000#-class that use Al castings, except the JD 3x20s
and some of the JD budget units.
(I even brought my magnet with me to the World AG Expo last month.)

 

[glc24]

I don't think I abuse my equipment,

Well,IMHO,you would have to ask yourself why I had 4 major failures in 160 hours. The poor thing isn't even broken in yet.

Do you think I have a "lemon" and should seek remediation with my local dealer?

You're either asking your 2520 to do tasks it isn't designed to do,or you're a pretty rough operator,and no I don't believe you have a lemon.You really should know the machines limitations. Ain't hatin',just sayin'.

If the 3PT arms have been rubbing that bad from the get go, shouldn't that problem have been addressed 160 hours ago.
Sorry if I sound harsh,but that's the way I see it.

Greg

 

[Wacky]

Hmmm, what happened to the OP.

 

[RoyJackson]

Why do you say that, Roy? Can you site a source?

Actually, it's conjecture on my part...knowing manufacturers build to a cost. Cast iron is pretty cheap, comparatively speaking.

I worked at a foundry a couple years ago...all aluminum, BTW. Aluminum castings aren't particularly cheap, but quite cost effective in low volumes. Also very machinable (depending on the alloy). They're also quite strong, if properly designed (Navy uses a bunch of them) which is why I'm not overly worried about the aluminum castings on my 4400. Must admit though, I would prefer cast iron.

Since cast steel was brought up...that's normally used in high stress situations (rail car couplers, for example). Not cheap, but very tough and long lasting.

 

[PCABE5]

One question, if the rears reduction gearboxes were replace twice before why didn't JD replace those 3pt arms under warranty after the first and/or second break? Known problem.

Being that it was in 4wd I see no evidence in the attached photos that he was spinning the tires. But if he did spin and it grabbed something it might break but I doubt very much that this was the case with an open axle setup. Or are we assuming he had it in 4wd and the rear diff lock engaged.

IMO, he would have had to be in reverse in order for the 3pt arm to have broken the axle. Based on tread design, going forward the tread would rub and in reverse the tire could try to climb the arm if it grabbed it right. Going up the 3pt arm something will give, tire, arm or axle.

Also IMO when in 4wd the front drive shaft is the weakest link rather than the reduction gear boxes.

 

[JDdude]

I never liked the looks of this planetary drive myself..But I just ordered a 2520 today because of the screaming deal I got..They gave me retail for my trade and wholesale on their 2520..

My farmer buddies told me that all of the combines use this kind of drive system and that I will never have any issues for the way I plan on using this tractor..I agree..So I ordered it..

 

[slowzuki]

Its not planetary, its a spur gear design. Was popular years ago (50+) until one brand became known for theirs breaking frequently in their tractors and bulldozers. Just now it seems to be coming back.

 

[jonyyuma]

Did you ever stop to think, of what it would cost to make Forged steel items and associated machining costs? Think tractor parts are high now???Example: Crankshafts for certain types of engines..Wow....I worked in IH foundry for a short spell, they poured cast iron and Malleable parts for many Mfrs. at that spot.White iron and cast was the softest type.Aluminum is much simpler to work with and machine, plus the processing is much easier and fool-proof.Hence, many parts of your machine are cast poured and need to be treated with respect.

 

[JDdude]

Its not planetary, its a spur gear design. Was popular years ago (50+) until one brand became known for theirs breaking frequently in their tractors and bulldozers. Just now it seems to be coming back.

I just call it that kind..I know it is gears and not the 3 gear in a gear deal..I will find out if it holds up I guess..done deal for me..

 

[PapaPerk]

I just call it that kind..I know it is gears and not the 3 gear in a gear deal..I will find out if it holds up I guess..done deal for me..

LOL! That's like calling an apple a pear. Both are fruit... but that's about it! LOL

Plantentaries are very rugged. A spur gear set-up... not so much.