weld failure?

TMGT · Jul 9, 2017

The weld shouldn't be supporting the load in that design, the material it passes through should be the main support, the weld keeps the shaft in place.
It needed more material and possibly a tighter fit where it passes through the yoke.

Big Barn · Jul 9, 2017

TMGT said:
The weld shouldn't be supporting the load in that design, the material it passes through should be the main support, the weld keeps the shaft in place.
It needed more material and possibly a tighter fit where it passes through the yoke.

This ^^^ is my opinion also. The design in this case was cheaply implemented though....

Terry

ratman3456 · Jul 12, 2017

It was a welding failure....first comment is spot on. Bevel rod and multi-pass it with 3/32 7018 at 95 amps.

17 Oaks · Jul 12, 2017

Bad weld, for the application would be my call. In fact I don't see enough weldment to hold a stamp on let alone the caster yoke. There is a reinforcement plate provided in the basic design and the size (thickness) looks structurally adequate. Guess the paint was painted over the weld, it appears wither not enough amps, or a dirty workpiece and just got tacked and then welder went to lunch, but the painter did not so it never got completed. I would have welded on both the top and bottom.

Not sure of diameter of the yoke, but it might may well have acted as a heat sink at welding time so the workpiece never got hot enough and the welding was not hot enough either.

lt190b · Jul 12, 2017

lt190b said:
Thanks to all who posted comments. The dealer called and said he had talked to gravely, said they had a production run with some problems. The one I "fixed" is still on the mower, I replaced the second broken one with the replacement one, it is a little different than the original ones. When I get the other new one (#2) I will post a picture of their fix so you can see it. To be continued.

This is it. (first picture) It is like the replacement one (#1) I have already put on. (second picture) is of the second failed one (#2) I am not real confident in this "new" fix. Time will tell. At least I have the original ones to hack up myself.

handtools · Jul 13, 2017

Very interested in this issue as I just ordered an Ariens Apex 60" with the Kohler 7000 25hp,(same as the Gravely ZT HD) the color of your caster fork appears to me to be Ariens orange not Gravely red. Have you had any other issues with the mower or are you generally satisfied?

lt190b · Jul 13, 2017

handtools, as to color, it matches the machine. I am sure there are colors that appear the same but have a different name. So far the only other problem was with the seat bolts, 2 with spacers fell out and were lost, the other 2 were loose, dealer furnished replacements. When I replaced them I put thread locker on them, this design is not perfect. Satisfaction is yet to be determined. Ours has the 24 hp kaw. engine

k0ua · Jul 13, 2017

Let me repair that thing with my little stick machine and some time beveling before the weld. If you could bevel out the top and lay even a small smooth bead on the top too, it would be Sooo much stronger. It shouldn't be a problem with the fit up. That's what I would do.

Gary Fowler · Jul 13, 2017

k0ua said:
Let me repair that thing with my little stick machine and some time beveling before the weld. If you could bevel out the top and lay even a small smooth bead on the top too, it would be Sooo much stronger. It shouldn't be a problem with the fit up. That's what I would do.

ME TOO. No reason it cant be welded from the top by putting a bevel and a flat weld. A grinder would fix any high spots.
I would bevel it from both sides and weld it. Since it has the backer plate on the bottom already it will require enough bevel so that you can weld the spindle to the yoke first, then weld the spindle to the backer. I guarantee that will hold till the spindle bends or the yoke twists.

CincyFlyer · Jul 15, 2017

Shield Arc said:
That is the big problem with Mig welding. People run them too cold. Even when a Mig weld is run cold, it looks good. BUT IT'S NOT!

Yeah, it's quite easy with a MIG to get a nice "fillet" weld that actually has a nice cavity below it. I always cranked mine until it was a little too hot (sunken edges) then backed up a tiny bit. Plus everything I ever built was over-engineered to a stupid degree, because steel is cheap!

Sodo · Jul 19, 2017

LT190B we need a pic from the "wheel side". Both old broken yoke and the new replacement yoke. If the new yoke is welded both sides (or tight hole) then possibly you won't need to repair the old one (as a spare).

flyerdan said:
Properly welded, an abuse failure on that part should have the shaft looking like a bent nail before it pulled out.

That shaft doesn't have enough support.
It's flexing the weld because it's loose in the bore, and then fatigue cracking the weld. Subjecting a weld to repeated fatigue stresses is BAD weld design.

On the "old" yoke, prepare like this, and weld boith sides, and you could bend that shaft like a nail before stressing the weld.

515908d1500482676-weld-failure-caster-wheel-yolk-002_chamfer-jpg

515909d1500482676-weld-failure-caster-wheel-yolk-001_chamweld-jpg

As James (and others) wrote:

k0ua said:
Let me repair that thing with my little stick machine and some time beveling before the weld. If you could bevel out the top and lay even a small smooth bead on the top too, it would be Sooo much stronger. It shouldn't be a problem with the fit up. That's what I would do.

This would solve it, MIG or stick.

If you can't do the weld on the wheel side, another way,,,, if there is space behind, is to simply "extend the shaft" on the backside. Lots of ways to do this depending on space available. Bevel out and re-weld the shaft as it was. Then add a 1/4" (or 3/8") thick "washer" and then plug-weld it onto the end of the shaft.

515907d1500482676-weld-failure-caster-wheel-yolk-001_addwasher-jpg

Need a pic fro the other side so we can see if the shaft is "tight" in the bore. Send pics of old and new. I suppose we have to wait to see if the new one breaks too? (for pics) If loose, you're gonna have to chamfer it and weld it, and the only way to do that, is with the shaft out ((with broken weld as in your first pic).

flyerdan · Jul 19, 2017

Sodo, thanks for taking the time to photoshop all those pics to illustrate properly welded. That makes it quite clear how the part should have been made from the get go, and how to permanently fix it.

lt190b · Jul 22, 2017

Sodo said:
LT190B we need a pic from the "wheel side". Both old broken yoke and the new replacement yoke. If the new yoke is welded both sides (or tight hole) then possibly you won't need to repair the old one (as a spare).

That shaft doesn't have enough support.
It's flexing the weld because it's loose in the bore, and then fatigue cracking the weld. Subjecting a weld to repeated fatigue stresses is BAD weld design.

On the "old" yoke, prepare like this, and weld boith sides, and you could bend that shaft like a nail before stressing the weld.

As James (and others) wrote:

This would solve it, MIG or stick.

If you can't do the weld on the wheel side, another way,,,, if there is space behind, is to simply "extend the shaft" on the backside. Lots of ways to do this depending on space available. Bevel out and re-weld the shaft as it was. Then add a 1/4" (or 3/8") thick "washer" and then plug-weld it onto the end of the shaft.

Need a pic fro the other side so we can see if the shaft is "tight" in the bore. Send pics of old and new. I suppose we have to wait to see if the new one breaks too? (for pics) If loose, you're gonna have to chamfer it and weld it, and the only way to do that, is with the shaft out ((with broken weld as in your first pic).