Broken bolt

[aczlan]

Grease has nothing to do with that bolt shearing. Look at his picture carefully. He has an arrow pointing at the grease zerk. If that joint is over greased it will simply squish out around the bottom edge of the cap. I grease mine until it does.

The large bolt that he circled is the one that is broken. That is a very serious breakdown. The tractor should not be used again until that's repaired. By used I mean don't drive it at all. Tomorrow morning you need to call your dealer or visit them with pictures. They will have to service the tractor where it's sitting.

Excellent advice. If the other bolt fails or the bracket bends, it could cause the gears in the axle to bind/rip apart and that would be a very bad thing.

Aaron Z

 

[ovrszd]

Excellent advice. If the other bolt fails or the bracket bends, it could cause the gears in the axle to bind/rip apart and that would be a very bad thing.

Aaron Z

Yep. Be hard to explain to the dealer why you drove the tractor knowing fully well the front hub assembly is falling off.......

 

[Spud68]

Lots of good info here. I plan to call the dealer in the morning as soon as they open. I would think they could just send a truck out, remove the broken part of the bolt and check the hub and replace 2 bolts. should take no longer than a couple of hours. you would think.... BTW here are pics of the bolt head and shaft that came out. Notice the head has never been touched after they painted it so they cant say I was messing with the bolt.

ovrszd, I also paid a premium for the warranty so I didn't have to worry about stuff like this. just sucks to be just getting ready to start her up and do some work and then a big POP while greasing the fitting. I was looking for the grease to come out of the bottom and then bang. oh well now to the pics....



BTW if anyone wants to take a gander of my little retirement project here is our Facebook page chronicling the project from cutover to homestead.
Reynard's Hollow | Facebook
Its called Reynard's Hollow.

Thanks again for all the great advise and help!
Teddy

 

[aczlan]

I would have them chase the threads with a tap before they put a new bolt in to make sure the bolt didn't mess up the threads on the way out.

Aaron Z

 

[oosik]

That pic on the left - the bolt has an unusual appearance. Stress failure or stress fracture doesn't normally produce a bolt that looks like that. That bolt looks like its been squeezed and sheared off.

 

[MHarryE]

BOLT FAILURES

You might want to take a look at this link. Compare your bolt to Figure 3. Appear to have the same 45ｰ shear plane typical of an overload failure.

http://www.boltscience.com/pages/Failure Modes.swf

The second link - go to slide 7 to see the same type of failure mode, also shown to have resulted from overload.

 

[s219]

I don't think the bolt was over-torqued, as that would have left somewhat of a helical fracture surface. In this case, it looks like it was an extreme tension load along the length of the boat. How the heck could that have happened? I am having a hard time envisioning a situation where that bolt would get an extreme tension load.

Might be interesting to see a closeup photo of the fracture face, to see if there is an obvious defect in the bolt. If that were the case, I'd expect it to fail in torsion when being torqued down, but who knows.

 

[oosik]

s219 - exactly my thoughts also. I can't figure how a bolt at that location would be subject to a load that would shear it off or stretch it like that. There could well be something else going on here. I figured the head of the bolt would be just popped off but that picture casts a different light on this situation.

Teddy - I would be sure that the dealership gets a chance to see that bolt - shown in your pictures. I would want them to determine the cause of this problem and not just replace the bolt. I would also have them check all the bolts on both sides for signs of failure.

 

[olPete]

s219 - exactly my thoughts also. I can't figure how a bolt at that location would be subject to a load that would shear it off or stretch it like that. There could well be something else going on here. I figured the head of the bolt would be just popped off but that picture casts a different light on this situation.

Teddy - I would be sure that the dealership gets a chance to see that bolt - shown in your pictures. I would want them to determine the cause of this problem and not just replace the bolt. I would also have them check all the bolts on both sides for signs of failure.

I reckon you could lift the whole tractor by that bolt and not break it to look like that. Will be interested to keep following this one til we hear the dealer's findings. Looks to me like both a dud bolt and overtorquing? Because if it was a branch or something that hit, I'd think the tractor would still be parked on it I have one that looks similar and it took major operator failure to do that.
To put my error into perspective...
I may have clipped a concrete post with an 8' side mower while mowing silage. Hit the frame just at the end..
The frame has already had a hard time. That's why I bought it for $50.. its mounting bracket is 6 inches square as was held on by 4 12mm bolts, that's a touch under a 1/2"... two were already snapped off in the casting, one bent and had a crack between the threads but I got it out with no trouble, the other looked like the one in the OP's picture. Welded on a ring spanner to get it out as it was well seized in there. So that's a huge amount of leverage across a small area, plus half the bolts already gone, to get a 45° shear on a much smaller bolt.

 

[Spud68]

S219, here is a closeup of the bolt face. I am really interested to find out the cause as well.



Teddy

 

[ovrszd]

Me too.

I work the snot out of my M9540. 1100hrs. Majority of those hours doing FEL work with a Grapple. Many, many times with one rear tire off the ground. The basic design of these front axles is very strong and proven.

There's something very unusual about this failure.

I'm glad you caught it while greasing the tractor rather than when carrying a heavy load.....

 

[s219]

S219, here is a closeup of the bolt face. I am really interested to find out the cause as well.

View attachment 497748

Teddy

Well, it looks like the outer part of the bolt, where you see the zig-zag of the threads in the upper-left of the photo, has both a shiny appearance and some rust, which suggests it was cracked for a while. The shiny part would have come from the metal rubbing against itself, and the rust from exposure. Hard to say from the photo -- does it look like that to your eye? The inner part looks more like a fresh fracture. As to what caused the original crack, hard to say. It's possible the heat treatment was not right, making the bolt susceptible to fail in this unusual way. Don't see any defects in the freshly fractured portion.

One possibility is that the bolt went in off-kilter for some reason, either cross threaded, or the receiving tapped hole was not perfectly perpendicular to the surface, or the bolt threads were not cut right, and then when the head was snugged down flat, it bent the bolt. Does it perhaps look like it may have gotten bent slightly? Any indication the threads took abuse? That would probably lead to the type of fracture seen in the photo.

 

[ovrszd]

To me, in his first pic of the bolt, it looks bent. But that could have happened as it broke?

 

[dodge man]

If you look at the link posted above, they show a pic of a bolt failure that is similar. It says its usually caused by another problem, one being the bolt actually not being tightned.

 

[Ford850]

Improper chain location, or chain binder over tightened. ??

 

[ovrszd]

Improper chain location, or chain binder over tightened. ??

Please elaborate??

 

[olPete]

To me, in his first pic of the bolt, it looks bent. But that could have happened as it broke?

At a guess. And only going by what my eyes tell me, that bolt had been partly cracked/fractured since it was installed, and just part in the middle is fresh. So it has probably been slightly bent if it's only been holding by a small area. Hard to say, only have a tiny screen but it sure wasn't grease pressure that did it, would it have been lashed down across the front axle, perhaps if the machine has nowhere handy as a lashing point, that it would be held down by a strap over there?
It's a job for the dealer to remedy, both sides!

 

[ovrszd]

Understand that the downward pressure of the tractor on this bolt pulls the two castings together, rather than pulling them apart. The more downward force applied, the more the two pieces press against each other.

So, unless you chain down the front tire assembly. Then chain down the tractor chassis separately. You can't create a force that would shear this bolt.

From what I see, there's much more going on here. Anxious to hear the results of the dealer's repair.

 

[olPete]

Agreed. I've just seen a number of really really big machines hauled and held down by the wheels and thought it may be a possibility. Am on the big screen now and realize it's not even the bolt I thought it was

 

[aczlan]

Agreed. I've just seen a number of really really big machines hauled and held down by the wheels and thought it may be a possibility. Am on the big screen now and realize it's not even the bolt I thought it was

The only way I could see that happening is if a chain was run over the top of that knuckle while the tractor was on the skid in transit across the ocean. Then I can see something being run over that point. Even then, I think they're bolted into the skid, not chained down.

Aaron Z