Question: structual welding/engineneering question.....

[Fingers]

If from deflection, crack would have been under the load, not the support. Actually would have bent or folded the beam under the load. Remember, the running gear more or less pivots with the frame. Very little cantilever action unless there is significant load aft of the front axle.

The trick with I beams is to get the load support to the top flange. The beam can hold much more than the web can handle in compression. So you want to add a vertical gusset to help transfer the force to the upper flange.

The other thing was the edge welding of the flange with a gap between the channel and the beam. Didn't help.

 

[malibu795]

the neck ripped due to slop in the coupler connection.. two 3/4" bolts through the coupler fixed that issues, along with Kaufman dropping the coupler like i asked them todo the first time..
they current. idea is to take 2" square .250" wall trunning from neck to subframe on suspension with gussets at each end..
currently the whole rig has been parked since November 8th '13

 

[Big Block 88]

How does the neck connect to the trailer now? One reason i went with loadmax trailers is the huge gussets that spead the necks load over the entire front of the trailer

 

[malibu795]

neck is 12" I Beam but welded with 5" wide ~2' long C-channel welded with the 'C' down.
the 12" beam starts at the bottom of the 10" main beam.

 

[malibu795]

how i fixed the coupler slop

 

[Big Block 88]

Pretty stout looking. Are those the factory welds on the neck itself? That is either a verticle up or a very poor and always weak verticle down? Looks like a verticle down to me welded too hot as addhesion looks poor on the tube surface i would keep an eye on it. I dont know who decides verticle down welds are acceptable on trailers, our car haulers both have down welded on them, both have been gouged out ground and rewelded by me in a verticle up. Even my big load max has downs on the neck but they look at least decent in the adhesion of the parts. I have even seen perosity in welds on trailers and flat beds. Drives me nuts

Is the neck itself tied into the front of the trailer all the way across? We have 40' h & h on the farm also and we had to add large gussets to the front of the trailer, you could see the twisting in the neck in comparison to the load on the trailer.

 

[Big Block 88]

Best image i have of the neck of the 35' load max it had twin bolts in the neck from the factory but it still had slop

 

[malibu795]

i twisted the oem set screw off on the original coupler thats the second one one it

 

[jlawles2]

If you wanted to get rid of the "slop" in the connector, I would have added another set screw at the top to force the internal tube back into the corner of the connector at 2 locations.

The slop you were / are feeling in the connection could be from the connector pivoting at the set screw.

Ideal solution would be to weld the connector solid once the ride height is set and adjustment is no longer needed. Welding it solid would required having holes drilled in the outer tube to plug weld the inner tube to prevent movement.

If the engineer needed to add strength but keep height to a minimum, adding plate to the flange could be a cost effective simple solution. I would prefer a slightly heavier beam instead of welding to the flanges to save cost and time.

Based on the original pictures showing the flanges not touching the running gear at the web, and the welds only being at the edges of the flange, fatigue has caused the weld to fail. Adding stiffeners may or may not fix the issue. Proper fitting of the running gear to the spine beams should result in a "bearing" connection across the flanges.

 

[malibu795]

i agree the 'bearing points' should not be focused on the weld points where it cracked/ripped, but spread evenly across the beam and subframe

 

[malibu795]

How I fixed the problem..
2x2x.25" wall tubing