Tractor broke in half again

[woodlandfarms]

Yup.. This time on me (this is the second time it has broke). Very odd. I think that probably the piece cracked earlier in the day and then slowly loosened up. Eventually just bowing like a broken down horse. I was able to get it back to the shop, and am figuring out the next moves.

Of course this happens at the end of my "big burns" where I set large (like 30X30X10) piles of downed trees on fire and clean it off. Now my fire will go out and there will be no more chance this year of a restart. Bumming.

Plan A is ordering a new part from PT. Plan B is having a part made at my local machine shop, something more substantial.

Terry says I can do the surgery myself but for whatever reason I am not comfortable with this. We will see. It is going to be a mess, raise the tractor, get beams under it so front and back match height and are level. Cut out the broken piece and put in the new piece (that will be the nightmare)

Not happy.

 

[MossRoad]

MAN!!! You are rough on that thing! What do you think is causing that? Too much lift? Too many PT pucker events? That just plain split that joint in half, didn't it?

Do you check the tightness of that joint on a regular basis? Grease it regularly? Hmm... maybe grease on that part wouldn't cause that crack. But a loose joint might contribute.

 

[Marks481]

What do you think is causing that?

Carl, you need to stop treating your little tractor like it is a motorbike. No more wheelies, ditch jumping and power sliding!

 

[4570Man]

I'd probably go for the beefed up custom made version. That's my usual approach to things that have proven the original version isn't strong enough.

 

[woodlandfarms]

Breaking an 1850 is not unheard of according to Terry. Breaking it twice... He and I will have a talk tomorrow (or Monday, not sure if they are open tomorrow).

65HP with chains adds some stress to the machine I am sure. I do tighten and grease, this is a metal fatigue crack. Kinda like we get on our rollover bars. In the end it looks like a schedule 40 pipe. Not much meat on the bone for holding together so much force. I also use the machine as a tractor, maxing out its lift potential, doing dirt work... I don't think i am easy on my machine but I do actually maintain it very well. But I do use it and I do use it at all of its capacities.

I have pondered if there is an issue with the front wheels getting less juice than the rear. that one pulls on the other more.

But either way, I think if I thicken up the walls on the center piece I will be in a much better space.

 

[MossRoad]

Great. Looking forward to the beef-up design. :thumbsup:

 

[pmsmechanic]

This looks interesting.

 

[Barryh]

Ouch !

 

[cqaigy2]

Go for the beefed up version. It might help to see what the next weakest part is, it could give us a clue about the stresses that are breaking your tractor.

 

[woodlandfarms]

So just had a nice talk with Terry and one of the head "engineers" who is a machinist. They both conclude that my break is happening due to twisting. So the PT has 12 degrees of twist (We are talking left wheel up, right wheel down, not turning). there are many occassions, due to my having large logs in the jaws of my grapple, that when I come out of a ravine sideways one wheel will be up in the air. As a matter of fact I had that experience the other day where a log shifted, and when I climbed out of the ravine I was one wheel high on the front.

Neither said much about me going for a thicker wall (its not what we have engineered) but neither would officially say it was abad idea.

I am ordering the new original. When it arrives i will take it down to my local machine shop and see if we can find a thicker wall item. I guess I am throwing money at the solution here. Not something I really want to do and pretty much guaranteeing me that I won't have my machine until christmas.

 

[MossRoad]

Well, that makes sense at least. Let's face it... you're in mountain goat mode and that's gonna stress that center point. Pretty amazing that it just climbs up and out of wherever you put it, though, isn't it?

 

[4570Man]

How big of a hurry do they get in shipping parts? I was thinking assuming your work schedule didn't get in the way it could be fixed in a week and your piles would be burning then.

 

[MossRoad]

They usually get parts out very fast. I'm guessing he has a life other than his machine ( how sad is that?). :laughing:

 

[ponytug]

Wow! Thanks for posting the photos; I didn’t understand it, until I saw it. Originally, I thought that you had broken the pin?

I vote for the beefed up version. That web around the inner ring is pretty thin, and the exterior web support stops at the half way mark, just where it failed. I would think about a steel triangle at least an inch thick with a hardened insert or bearing pressed in. You clearly need at least 3/4 of an inch, just based on the failure site. Can you get 1 of webbing all around it? If not, you may need to go to a stronger steel alloy. My two cents would be not to weld in the insert as PT did, as that induces thermal and chemical stress, weakening the outer half, and probably predisposing it to failure. A good welder ought to be able to repair that piece and add a thicker web around the ring and out toward the front half of the tractor. If it were me, I would be looking to double the strength of the web area that broke, by thicker steel, and / or stronger alloy, or both.

I don’t see that using chains, or being on three wheels is necessarily hard on the joint, but I do see that landing on the 4th wheel with full load and speed would be hard on that point.

Just a thought, you might want to try a slightly higher current or a larger rod putting the replacement triangle on the tractor. Those welds look a little on the cold side, which means you probably don’t have all the strength that you could have. Personally, I find thick and thin welding to both be rather challenging to get all of the parameters dialed in.

All the best,

Peter

 

[Marks481]

I am ordering the new original. When it arrives i will take it down to my local machine shop and see if we can find a thicker wall item.

Please take a picture of the part and post it when you get it.

Seems to me that it could be replaced by a piece of 3/4" plate, with the hole bored directly in the plate, and as much material outside the hole as possible but not touching the rest of the assembly at extreme tilt and pivot.

 

[pmsmechanic]

To me it seems like that pivot point is taking all the twisting forces when you are coming out of the woods on three wheels. If you could transfer those forces to something else that would be ideal.

Can you make the joint so that the twisting forces are not concentrated right at that small pivot point? Can you use a chain fastened to two points on the front and rear frames to limit the twist so the chain take the forces instead of the joint?

 

[MossRoad]

So what exactly broke?

The lower center pivot between the two sections?
Which part of it broke, the ears or the eye?

Don't know how the 1850 is constructed... my 425 has two ears on the rear section and one eye on the front section. The eye is pinned between the ears with a bolt that appears to have a grease channel drilled through the center of it.

The eye appears to be similar to a 3pt hitch lower link ball end. Anyone else notice that?


Category 1 lower link ball ends are 7/8" diameter.
Category 2 lower link ball ends are 1-1/8" diameter.
Category 3 lower link ball ends are 1-7/16" diameter.
Category 4 lower link ball ends are 2" diameter.

There's weld on balls.
Tractor Parts Inc - Weld On Lift Arm Balls

There's weld on ends with the balls already in them.
Tractor Parts Inc - Lift Arm Repair Ends

Anyhow, I'd take the broken part to Tractor supply, or some other agri-supply type place and compare it to the 3pt lower arm ball joints and see if they are compatible.

 

[MossRoad]

Like these...

 

[cqaigy2]

Those certainly look pretty similar, don't they.

 

[woodlandfarms]

When the item arrives next week I will take a picture of it. Think of it as a V piece of steel with a chunk of pipe welded on the end, which it is. Actually tubing (just learned that pipe and tubing are different). Anyway, Mine is the same as yours in a way. I have one piece on the front that connects between two ears on the back. A special pin, with steel bushings, goes inbetween.

I agree. When the original arrives I am going to have something cutom made I am sure. I need to have some pictures taken from Ken and his machine to make sure if I thicken up the pipe, or use a chunk of steel around it to reinforce, that it won't run into the cylinders, which is kinda my concern now.