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Olddawgsrule View Drop Down
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Posts: 1014 		Direct Link To This Post Topic: Floor failure!!!
    Posted: 12 Aug 2019 at 4:09pm
Trailer just left on the flatbed truck. Part two of the story begins!

With it up in the air and easy to sight, I see the axle middle section, mount to mount as really good. Much greater than the 1/8" I measured, but I went end to end.
Outboard on the slide side is definitely bent upward. I can see the bend. That's where it happened, slide side.

As I thought I saw, both beams are bent. 

The guy picking it up admitted it's his first trailer.. No kidding dude, I saw it in your eyes. There are times you hope for the Pro's to be smarter than you. Not in this case. Thankfully I was there..

Lippert will most probably stand behind their axle, but really doubting how much FR will stand behind. Guess it's all on the Dealership and what they can do for me.

Saddened beyond sayin'.. 
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mcarter View Drop Down
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Posts: 3419 		Direct Link To This Post Posted: 12 Aug 2019 at 4:01pm
Never saw that anywhere.
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Olddawgsrule View Drop Down
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Posts: 1014 		Direct Link To This Post Posted: 12 Aug 2019 at 1:45pm
This has always been a rumor for me, due never asking.. So I shall!

It's rumored that the HRE's have a 5200# axle. If true, are their frame's also of thicker steel?

I met a HRE owner that claimed his axle was a 5200#... 
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Olddawgsrule View Drop Down
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Posts: 1014 		Direct Link To This Post Posted: 12 Aug 2019 at 9:51am
Originally posted by offgrid

Olddawgsrule, I just had a thought. 

There is yet another force that will push upwards on the frame at that same "weak point". That is braking. If you were to brake aggressively you would get a lot of torque acting on a moment arm extending from the tire contact patch up to the frame attachment, trying to twist the frame. That moment arm is pretty big especially if you have a riser kit. My moment arm for that braking force is about 14 inches, twice the 7 inch arm of the torsion axle itself (I have risers and 15 inch tires). That means that if the braking force was about the same as the down force the effect is twice as large at that "weak point". I'm sure that none of us are able to get that much stopping power out of our trailer brakes but even so, aggressive braking is going to add significant stress at that point on the frame rail. 

Have you had to do any heavy braking lately that could have contributed to this? 

I can say no. I travel so carefully and leave so much room between myself and those around me. I travel from months at a time, so I'm overly cautious. My wife says I drive slower than her Grandmother did..
I do have 15" tires, but no lift. East Coast version. 

With all that said.. Wouldn't braking spread that force over both sides? Wouldn't then the torsion be working in my favor? Now 'I'm' learning enough to be dangerous.. or confusing the crap out of myself..
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offgrid View Drop Down
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Posts: 5290 		Direct Link To This Post Posted: 12 Aug 2019 at 8:31am
Olddawgsrule, I just had a thought. 

There is yet another force that will push upwards on the frame at that same "weak point". That is braking. If you were to brake aggressively you would get a lot of torque acting on a moment arm extending from the tire contact patch up to the frame attachment, trying to twist the frame. That moment arm is pretty big especially if you have a riser kit. My moment arm for that braking force is about 14 inches, twice the 7 inch arm of the torsion axle itself (I have risers and 15 inch tires). That means that if the braking force was about the same as the down force the effect is twice as large at that "weak point". I'm sure that none of us are able to get that much stopping power out of our trailer brakes but even so, aggressive braking is going to add significant stress at that point on the frame rail. 

Have you had to do any heavy braking lately that could have contributed to this? 
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offgrid View Drop Down
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Posts: 5290 		Direct Link To This Post Posted: 11 Aug 2019 at 2:49pm
Good luck....
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Olddawgsrule View Drop Down
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Posts: 1014 		Direct Link To This Post Posted: 11 Aug 2019 at 2:11pm
Supposedly, the flat bed truck comes tomorrow to haul it to the dealer..

The journey begins! 
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Posts: 5290 		Direct Link To This Post Posted: 10 Aug 2019 at 3:05pm
Originally posted by Olddawgsrule

Care to guess where the fracture is??

Yep, it figures. 

The only "easy" reinforcement fixes I can think of offhand would either be to weld angles to the bottom and outside of the frame tubes and then bolt up the axle brackets, or to make up longer axle risers and weld on new attachment brackets to mate to them. 3 or 4 feet total length would probably bring the stresses down to something fairly reasonable.  Or you could convert to leaf springs, but even then some additional frame reinforcement in that area would still probably be a good idea. 

I'm partial to a nice craft brewed IPA BTWThumbs Up
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Posts: 5290 		Direct Link To This Post Posted: 10 Aug 2019 at 2:23pm
I'm not an ME, actually my degree is in Physics, so I like to say I know enough to be dangerous LOL 

But I've wound up doing a lot of mechanical, electrical, and thermal engineering in order to design and manage engineering teams designing solar projects. 

I've always seen structural systems designed using allowable load (eg, based on the 36ksi number for mild steel). Above that and you can get plastic deformation, meaning that the metal bends and stays bent. Ultimate yield is the point at which the steel will break after having been stressed beyond the allowable design point. It deforms first way before breaking, so that's not the number to be using for our frame and axle designs. 

I think your friend raises an interesting point. He is probably referring to fatigue fractures. You get fatigue fractures starting where there are tiny discontinuities in the steel, which there always are. These can then propagate slowly over thousands or tens of thousands of load cycles, eventually resulting in breakage failures. They can occur at stress levels well below ultimate.  For steels the endurance limit threshold below which cyclic loads can continue essentially indefinitely without fracture propagation is generally taken as about half ultimate yield, so around 30ksi or 1.31g which is a little less than allowable design stress. 

If our frames were designed more conservatively, say around a 2.5-3g allowable load, we would get very few if any cycles above the threshold so no opportunity for propagation of fractures to occur. But at about 1.3g we are likely getting some significant number cycles above the threshold and so there is the possibility for fractures to occur even if we're not quite reaching the point where we are bending the frames. Are we getting tens of thousands of cycles at that level? Who knows? 

Bottom line IMHO is we are under designed and so subject to a variety of failure modes in our axles and frames that we really shouldn't be having to deal with. 
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Posts: 1014 		Direct Link To This Post Posted: 10 Aug 2019 at 12:50pm
Care to guess where the fracture is??
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