Trailer Axle Weld Failure Question

[Don52]

The weld that attached the flange to the axle tube failed. The wheel assembly up to the axle flange fell off as shown in Picture 1. Picture 2 shows a close up of the failed weld on axle tube. I believe that the bottom portion of weld failed first because it was rusty as shown in picture 3. The top part is crushed so if you put the pieces back together there is now a crack as shown in picture 4 on the top. This indicates that the top portion of the weld acted like a hinge and was last part of the weld to let go. To me it looked like the spindle was a press or shrink fit in the axle flange. Picture 5 is a close up of the interface between the flange and the spindle. I don't see any upset metal at the interface between the spindle and the flange, which would be indicative of a friction weld. There is some blue color on the top of the spindle indicating that it was heated at some point. Perhaps they heated the hub of the flange before they installed the spindle as a shrink fit. It is possible that they welded the flange to the axle tube after the spindle was press fit into the flange and the blue color was from the heat due to welding. Picture 6 shows the whole flange spindle assembly and picture 7 shows the spindle side of the connection between the spindle and the flange.

I was concerned that if I welded the flange back to the axle tube, that the process of welding would stress relieve the hub of the flange and diminish the press or shrink fit. I told my customer that he should replace the axle, which he did.

• Do you agree with my recommendation to replace the axle or would you have just welded it?

[Don52]

And here are the last two pictures:

[walker]

I don't agree that it would do any damage to the spindle pilot, it was welded before. Not really a shrink fit, or really even a press fit, just helps with alignment when building the axle. I do agree with replacing the axle. It was likely overloaded, though the weld is garbage. The other side is probably in near the same shape. Cheaper to replace it than to fix it though.
If it was mine I would have cleaned it up and welded it, and likely ground out the other side and welded that as well. Then I would have inspected the rear axle.

[MMW]

I agree with walker on all points. It could have been fixed but the cost & availability of a new one is cheap enough to just replace it.

I also agree with your theory on how it broke. Bottom first then top acting like hinge.

[Don52]

It was likely overloaded, though the weld is garbage.

Thanks for taking the time to respond.
I agree. Clearly the weld joint design was not adequate for the loads that it experienced. In the following picture the axle is upside down. So the weld that you see on the top, would be on the bottom when installed on the trailer. The weld makes up between 25% and 30% of the cross section. If the weld joint was designed for more penetration I don't think that it would have failed.

[aametalmaster]

Ahh high school kids welding axles after school in a trailer factory. Brings back lots of memories. I welded hundreds of them before graduation...Bob

[Don52]

Added

I welded hundreds of them before graduation...Bob

Bob,

I couldn't see any weld between the spindle and the flange.
The blue color stops and starts on the end of the spindle are aligned with the MIG weld that attached the flange to the axle tube.

My guess for the assembly process is:
• Press fit the spindle into the flange.
• MIG welded the flange & spindle asm onto the end of the axle tube.

Do you know if the spindle is typically welded to the flange in addition to the press fit?

In the attached there are two pictures of available spindles. The first can be purchased for $21 and looks just like the one in question. The second spindle assemble is $65. On the second I can clearly see the weld that attaches the spindle to the flange. On the spindle of the axle in question and the first attachment I don't see a weld. The spindle shaft engagement is so little I can't believe that they are depending on just a press fit.

Don

[MMW]

The weld may have been fine for rated load (or maybe not). But most people really overload these trailers at one time or another. I have seen numerous times trailer axles that are decambered due to being over loaded. Overloaded & then hitting a curb going around a corner or a big pot hole can = breakage. Also being fully loaded constantly can lead to fatigue which can also lead to it breaking.

[ryanjones2150]

I've built a few trailers for myself and my friends and family. For myself, I generally try to scrounge the parts because I'm cheap and I like to resurrect old stuff and make it better. Doing a little tear drop camper for myself here lately and had to shorten the axle by about three inches, so I cut the spindle off and welded it back on, I wasn't impressed with the amount/penetration of weldment. Pretty much exactly what you're showing in your cross section there. I didn't even have to cut into the spindle hub to get it free of the tube. My guess is you could do the same to most axles down at your local trailer supply and find that exact scenario. I tend to over-engineer stuff, like many of you guys do I'm willing to bet, so we have a habit of looking at that stuff and just shaking our heads.

I haven't been exactly impressed with most of the trailers built by many of these mass production lines. They can sell trailers at really good deals because of stuff just like this. I recently bought a little bitty enclosed trailer from an outfit over in Georgia, drug it home to Texas, noticed it wasn't sitting straight. Climbed under it and found two cross members that weren't welded to the frame rails at all and most of the welds that were on there looked like a blind man did them with his feet. Top it off, they ended up grounding through one of the spring hanger bolts during welding and locked it up solid so it wouldn't flex and ultimately caused a bent spring. I called the company up a day or so later and they pretty much told me tough luck. If I wasn't happy with it I could bring it back to them. Nice to see a good quality American company standing behind their products eh? Anyway, I have no doubt axles are produced in places just like that.

[aametalmaster]

Bob,


Do you know if the spindle is typically welded to the flange in addition to the press fit?

Every axle our shop made the spindle was pressed into the back plate then welded with 7018 on both sides before it was mig welded to the tube. But lots have changed in 30 years. I have seen some crummy looking ones too now days...Bob

[kevin]

Ahh high school kids welding axles after school in a trailer factory. Brings back lots of memories. I welded hundreds of them before graduation...Bob

hahahaha still see ads in the help wanted, mig welders wanted, no experience needed, will train 10 to 12 bucks an hour. looks like this kid forgot to put enough weld on it