New and Improved Spring Hanger Failure!

[chattacuda]

Ken,

Maybe a better pic of this area from the OP could help answer some questions. Wonder if someone has jacked up the side of the rig from the CRE3000. That would bend the hanger but missing material on the CRE3000 would be hard to do short of grinding on it.

Jim

I wiped the dirt off and this thing is shiny. I have never jacked the rig up as it only had less than 1k miles on it before this trip. I feel certain I would have seen this on the PDI and noticed the listing to the side. Keep the theories coming! It will probably be a few weeks before I tackle this. The I beam web is obviously bent too in addition to the flange. You cant really see it in the pics but I can feel it. It is bent below the re-inforcing plate welded on where the slide mechanism penetration is.

Larry

[Guest]

I wiped the dirt off and this thing is shiny. I have never jacked the rig up as it only had less than 1k miles on it before this trip. I feel certain I would have seen this on the PDI and noticed the listing to the side. Keep the theories coming! It will probably be a few weeks before I tackle this. The I beam web is obviously bent too in addition to the flange. You cant really see it in the pics but I can feel it. It is bent below the re-inforcing plate welded on where the slide mechanism penetration is.

Larry

Thanks for the new pics Larry. The CRE3000 looks to be ok on the bottom area where that must have been a reflection. I'm still sticking with the theories that have been posted. Do you recall encountering a drop off on the berm of the road anywhere? It seems that if the rig left the road over a berm, possibly on a curve, the shifting weight of the rig would put a great deal of stress on the center hanger on that side. Or striking a curb on a sidewall? Are there any scuffing on the outer sidewall of the tires on that side? I could see the bent frame in your earlier pics where the V Clips will stiffen up the hanger but will also translate more energy into the frame in extreme conditions. Especially in the small un-reinforced area where the bending occurred. We call this a stress concentration area. Really unfortunate this happened to you.

Jim

[Jlawles2]

The failure method appears to be a form of web crippling. Not shown in the first set of pictures was the penetrations in the web for the slide mechanism. By chance in your travel day, was there a lot of harmonic bouncing on the roadway? If so, hitting the frequency of the suspension can actually result in a huge dynamic loading as the trailer continually bounces up and down amplifying the effects at every rebound.

With the penetrations, the web is weakened in the area. Adding the small angled plates on the sides of the flange to web are there to prevent the flange from rolling at the web. All this really does is move the potential failure point up into the web. To properly combat the web failure point (in my opinion and from some experience) there should be on one side a set of vertical stiffeners to "box" the high stress area, otherwise the angled plate should be much longer and better attached to distribute the torque from the bottom flange across a wider area into the web.

Rob from Cate&Rob may have a bit more of a technical explanation as I think he was in the suspension field, if not then he will remember who was.

[Cate&Rob]

Picture 3 in post 16 may “tell the tale” of what is going on here. Placing large through frame openings directly above a suspension attachment point would not seem to be a good idea. There is a web reinforcement plate around these holes, but the horizontal bend point is clearly across the bottom of these openings in the frame web. As Joseph notes, “boxing” the frame from flange to flange would be a lot more effective reinforcement than a plate welded to the web and another at 45 degrees from flange to web.

I would think that getting the frame flange bent back into position and then boxing it to the upper flange on each side of the openings would be the best plan (but difficult to do). This is going to require heavy frame straightening equipment.

Rob

[chattacuda]

Thanks for the new pics Larry. The CRE3000 looks to be ok on the bottom area where that must have been a reflection. I'm still sticking with the theories that have been posted. Do you recall encountering a drop off on the berm of the road anywhere? It seems that if the rig left the road over a berm, possibly on a curve, the shifting weight of the rig would put a great deal of stress on the center hanger on that side. Or striking a curb on a sidewall? Are there any scuffing on the outer sidewall of the tires on that side? I could see the bent frame in your earlier pics where the V Clips will stiffen up the hanger but will also translate more energy into the frame in extreme conditions. Especially in the small un-reinforced area where the bending occurred. We call this a stress concentration area. Really unfortunate this happened to you.

Jim

Thanks Jim
i am a retired mechanical engineer and more do metal fabrication as a hobby so I sort of understand the force it took to bend this frame. You mention dropping off the road as a potential cause. I do remember traveling on a local state road on one of our previous trips and dropping off that side in a right hand curve where the pavement had collapsed previously. It was a small drop and I only noticed it because the camper wiggled a little. That could have been the event but it was so minor I didn’t even give it a second thought other than I need to swing wider next time. I was probably doing 35mph

Larry

[Guest]

Thanks Jim
i am a retired mechanical engineer and more do metal fabrication as a hobby so I sort of understand the force it took to bend this frame. You mention dropping off the road as a potential cause. I do remember traveling on a local state road on one of our previous trips and dropping off that side in a right hand curve where the pavement had collapsed previously. It was a small drop and I only noticed it because the camper wiggled a little. That could have been the event but it was so minor I didn’t even give it a second thought other than I need to swing wider next time. I was probably doing 35mph

Larry

Larry,

This event as well as (I suspect) the lack of a Finite Element analysis tools to properly design the frame with the large opening in the web has resulted in a failure. As you know, it requires modern engineering tools to get this design right. These frames move laterally as well as vertically where it appears the excessive lateral motion resulted in the frame yielding in a concentrated stress region. A properly designed cross member would have prevented this issue but that does not help now. The key here is to re-enforce the area while being careful with the heat affected zone in welding, so a plate should not be welded in fully around its perimeter. I would still install the X factor bracket as a final fix.

A good frame shop may use a portapower tool or something similar to the attached to straighten the web. Used portapowers many times years ago where they are very powerful.

https://www.amazon.com/OTC-5180-Capa.../dp/B002Z36UE0

An over the top tool demo.
https://www.youtube.com/watch?v=mjVTGGWG-DA
Jim

[Yoda]

I wiped the dirt off and this thing is shiny. I have never jacked the rig up as it only had less than 1k miles on it before this trip. I feel certain I would have seen this on the PDI and noticed the listing to the side. Keep the theories coming! It will probably be a few weeks before I tackle this. The I beam web is obviously bent too in addition to the flange. You cant really see it in the pics but I can feel it. It is bent below the re-inforcing plate welded on where the slide mechanism penetration is.

Larry

Larry
In picture #1 there is a white washer. The Cree pivot assembly appear to be ****ed in it housing (badly tilted) and the housing splayed. Is the second washer on the back side still there? If not the way it is tilted could cause leverage on the mount. Be sure to talk with Lippert before having someone heat up the flange to bend back in place. As you probably know heating steel can weaken it in the long run, just as improper welds can cause cracking if not done properly and the proper rod used.

BTW Rob is spot on identifying the weak point where the bend occurred. That flange where the slide penetrated should have been doubled up the full width between the webs.

Keith

On edit



Also in picture # to the side of the Cree mount appears to be bowed slightly.

[Guest]

See the last two sentences in post #17.

[TedS]

Is the hanger not attached directly under the chassis channel? Is the suspension not directly under the channel, but to the inside? That would put a bending load on the channel leg twisting the channel.

[chattacuda]

Is the hanger not attached directly under the chassis channel? Is the suspension not directly under the channel, but to the inside? That would put a bending load on the channel leg twisting the channel.

Ted

It is supposed to be directly under the I beam, as is the other side. Its movement inboard is the result of the problem, not the cause. I suspect I dropped that side off the road momentarily because it looks like the two springs on that side are also flatter which means to me they must have overloaded from the impact.

Its still a mystery and probably will remain that way.

Larry

[chattacuda]

Larry
In picture #1 there is a white washer. The Cree pivot assembly appear to be ****ed in it housing (badly tilted) and the housing splayed. Is the second washer on the back side still there? If not the way it is tilted could cause leverage on the mount. Be sure to talk with Lippert before having someone heat up the flange to bend back in place. As you probably know heating steel can weaken it in the long run, just as improper welds can cause cracking if not done properly and the proper rod used.

BTW Rob is spot on identifying the weak point where the bend occurred. That flange where the slide penetrated should have been doubled up the full width between the webs.

Keith

On edit



Also in picture # to the side of the Cree mount appears to be bowed slightly.

Keith

I think the other washer is still there, just cracked and displaced upwards. I'll let you know when I get into it. Been working on winterizing stuff here before the freeze. I'm still coming up with whatever tooling I will use to straighten it. Good idea about calling Lippert; I am assuming they have never seen anything like this before but maybe I will get surprised.

Thanks again
Larry

[Guest]

The CRE3000 is not the issue but has received damage from the bending frame. The springs are exhibiting a force to try and hold the CRE3000 (blue part) straight while the bent frame has shifted the outer frame of the CRE300 over. This was a lateral bending moment induced by the drop off of the road, the shifting mass of the rig, the already documented high lateral loads exhibited primarily to the center hangers and the unsupported highly stress concentrated area of the frame. Engineering 101.

Jim

[Jlawles2]

chattacuda Don't want to discard any of the opinions of any of the post, but as I ponder the changes to the deformed set of spring hangers, The opposing side needs to be inspected. When the frame bent on the one side, it threw off the geometry of the opposing side. Likewise this put a lot of stress on the springs themselves. Both the bent side and the opposing side springs are possibly side loaded and could be twisted.

The amount of force needed to straighten the frame could be quite high. If there is a local frame and alignment shop, you may want to stop by there and talk to the frame machine operator. IF they have one with hydraulic arms and can get the camper in the right spot, for them to correct the frame will be quick.

After all of the straightening is completed, you may consider replacing the small diagonal plate between the flange and the web with a much longer one, followed by increasing the strength of the web locally by use of vertical gussets between the flanges, notching the diagonal plate to allow for proper fitting.

You may want to consider inspecting and possibly replacing all of the springs in the system once the repairs are complete.

[chattacuda]

After much consideration I have decided to replace the spring hung design with the Morryde Independent Suspension. I am too old to be worrying about a poor design causing problems down the road. I considered putting it back like it was from the factory and adding the cross brace to the center or all three hangers, but that does not eliminate the inherent weakness in the I beam above the center hanger where the slide out mechanism is. Would a cross brace be adequate; maybe. But I would always be worrying about it. I really appreciate everyone'e comments. I realize I still have to straighten the frame for the trip to Morryde in Indiana in Feb/March but that is OK and I know I can do it. I will update this post as time goes by and I see exactly what it takes to fix this mess. Thanks again everyone

Larry and Angie

[chattacuda]

So....I have disassembled the curb side to see what all is going on. Turns out worse than I originally thought....imagine that! I'll let the pics tell the story but the short version is I obviously hit something. It appears the front axle hit so hard the axle itself contacted the frame and the tire hit the tire well and distorted it. The frame I beam above the front axle is bowed inwards about 1/2". The back tire contacted the fender well slightly also. I have a mess on my hands. I have to straighten the I beam enough to get it to Morryde in January for the IS install. Ughh. I will keep you all posted.