Trailer frame gussets and stress risers

Gbkeith

Gbkeith

Ai-yi-yi, Katie
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I’m building a hay trailer out of 8x11.5 channel. Welding the cross members to the frame rail like so.
IMG_4441.jpeg


I’m going to burn out some nice radiused gussets. I was intending on putting them on both sides like this, but if I do does that just put a stress riser at the line where the gussets end on the crossmember? Or since it’s tapered down by then is it irrelevant?

IMG_4442.jpeg
 
I don't understand the point of the gussets. Are you worried about the trailer turning into a diamond when you back one corner hard into something?
 
I'm assuming you are putting them in the center of the cross member. There you should be close enough to the neutral point that it doesn't add a stress riser. I'm not entirely sure I understand the point of the gussets either though.
 
speed bump said:
I'm assuming you are putting them in the center of the cross member. There you should be close enough to the neutral point that it doesn't add a stress riser. I'm not entirely sure I understand the point of the gussets either though.
Click to expand...
I was assuming he was doing top flange and bottom flange. :laughing:
 
I was in a hurry and should have clarified better.

Gussets at top and bottom flanges. Mostly for the purpose of spreading out the forces from the crossmembers into the frame rails when the hay bales dump. The tongue and the bumper tube hopefully keep it square when I back into something.
 
Gbkeith said:
I was in a hurry and should have clarified better.

Gussets at top and bottom flanges. Mostly for the purpose of spreading out the forces from the crossmembers into the frame rails when the hay bales dump. The tongue and the bumper tube hopefully keep it square when I back into something.
Click to expand...

Do you expect it to twist a lot when its being used?
 
Gbkeith said:
I was in a hurry and should have clarified better.

Gussets at top and bottom flanges. Mostly for the purpose of spreading out the forces from the crossmembers into the frame rails when the hay bales dump. The tongue and the bumper tube hopefully keep it square when I back into something.
Click to expand...
Seems like the wrong place to put a gusset in to help that. I've designed assemblies where we ran a piece of flat bar across the rails and tied in the cross members but that was because we were worried about flexing in the legs direction. For a trailer I would probably just run it in to the web and weld it. For stuff I want to massively abuse I would run angle off the rails and punch holes for bolts so I had give in my joints but trailers seem to hold up okay after being blasted together with hard wire.
 
do find a trailer that exists that you are wanting and take a peek
then make it stronger (I have seen trailers that aren't even welded on the bottom)
 
SomeGuyFromOlympia said:
do find a trailer that exists that you are wanting and take a peek
then make it stronger (I have seen trailers that aren't even welded on the bottom)
Click to expand...
My 10k Hudson had the crossmembers welded in by the top and bottom flanges only and on one side. I assume that back in 1982 Methy Marty dropped them in there and welded the two seams that were in the flat position with the trailer right side up. Needless to say I fixed that. :laughing:
 
3 axis constraint and weld toes in a high tension area will be the biggest concern of stress risers you will want to consider in your design.

Your detail will increase your racking resistance, as mentioned by others, but you're not gaining much in shear or bending of the cross members. Between the bumper and the axle, the top set of your gussets would be effective and not create a increase in a stress riser as they are going to be more in compression as the Channel frame bends. OVER the axle, is different because your bending moment is negative.
Honestly, a good web to web connection with clip angles or will give you a lot of the capacity that I believe you are looking for.

speed bump said:
Seems like the wrong place to put a gusset in to help that. I've designed assemblies where we ran a piece of flat bar across the rails and tied in the cross members but that was because we were worried about flexing in the legs direction. For a trailer I would probably just run it in to the web and weld it. For stuff I want to massively abuse I would run angle off the rails and punch holes for bolts so I had give in my joints but trailers seem to hold up okay after being blasted together with hard wire.
Click to expand...

This is how bridge diaphragms are installed these days. They've found out that fatigue life of gussets and cover plates on flanges are at best, 1/10th the fatigue life of a bolted connection.
 
Gbkeith said:
I was in a hurry and should have clarified better.

Gussets at top and bottom flanges. Mostly for the purpose of spreading out the forces from the crossmembers into the frame rails when the hay bales dump. The tongue and the bumper tube hopefully keep it square when I back into something.
Click to expand...
If you are loading one side at a time and worried about twisting it or even the one crazy time that you have to load it with all the wright on one corner. Then id try to fit the longest torque tube that you could down the center. Id put it low as possible. Like just above the axle tubes at full bump from the front bulkhead to the end of the trailer.
 
The frame itself should be rigid.

IMG_4447.jpeg

From the back tube, the first, second, fourth, and fifth crossmembers are going to support bale cradles. Each cradle gets a lever, when I pull a lever that bale dumps off the right hand side.
IMG_4448.jpeg

The trailer will weigh around 1100 pounds, and loaded it’ll have 1800-3000 pounds 3 foot above deck height. And when it dumps 900-1500 pounds slams down on the right hand side.

Mostly I’m just trying to over do things so it doesn’t fall apart anytime soon.
 
ANGRYBLACK said:
If you are loading one side at a time and worried about twisting it or even the one crazy time that you have to load it with all the wright on one corner. Then id try to fit the longest torque tube that you could down the center. Id put it low as possible. Like just above the axle tubes at full bump from the front bulkhead to the end of the trailer.
Click to expand...
I’ve got one, but it’s an inch above centerline of the frame so that it ties into the center of the 4x6 rear bumper tube.
 
lol totally not needed even in mad max overkill mode. Go look at your 35t trailers they will not have gussets on them.

Waste of time and money imo. You put down quality welds and your hay wagon will last forever. If your welding with a flux cored harbor freight 110v welder then maybe you should put them in. You weld it with .045 dual shield or 3/32 7018 and it will be gtg.
 
I'd skip the pivoting tipper bale body since you're wasting effort and weight on basically having two frames by doing that and instead find a way to make the whole trailer tip or otherwise

Swivel coupler up front is easy with tube in tube. Axle can be made to pivot pretty easily if it's on a sub-frame. Shouldn't need to make it tip all that far if the side boards can be un-pinned.
 
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arse_sidewards said:
I'd skip the pivoting tipper bale body since you're wasting effort and weight on basically having two frames by doing that and instead find a way to make the whole trailer tip.

Swivel coupler up front is easy with tube in tube. Axle can be made to pivot pretty easily if it's on a sub-frame.
Click to expand...
The point is to dump one bale at a time.
 
I'm sure if you go through with your plan it'll be pretty bomb proof and work well but I think your whole design could have a whole lot more lightness added to it.
 
ThePanzerFuhrer said:
lol totally not needed even in mad max overkill mode. Go look at your 35t trailers they will not have gussets on them.

Waste of time and money imo. You put down quality welds and your hay wagon will last forever. If your welding with a flux cored harbor freight 110v welder then maybe you should put them in. You weld it with .045 dual shield or 3/32 7018 and it will be gtg.
Click to expand...
See, my brain knows all that, and I’ve looked at a lot of trailers. I just have trouble not saying **** it and welding something h else on.
 
Gbkeith said:
See, my brain knows all that, and I’ve looked at a lot of trailers. I just have trouble not saying **** it and welding something h else on.
Click to expand...

Honestly, that's probably the beefiest hay bail trailer frame I've ever seen. All the ones around here are made of pipe. I doubt you will have any problems as it sits.
 
arse_sidewards said:
I'm sure if you go through with your plan it'll be pretty bomb proof and work well but I think your whole design could have a whole lot more lightness added to it.
Click to expand...
If I had a bunch of four or six inch channel sitting around instead of eight inch that would save a few pounds also. I’m not that worried about the weight. To make everything clear and keep it the length I wanted, and account for different sized bales, I’m actually adding stuff to the front mostly to keep tongue weight where I want it to be.
 
AlxJ64 said:
3 axis constraint and weld toes in a high tension area will be the biggest concern of stress risers you will want to consider in your design.

Your detail will increase your racking resistance, as mentioned by others, but you're not gaining much in shear or bending of the cross members. Between the bumper and the axle, the top set of your gussets would be effective and not create a increase in a stress riser as they are going to be more in compression as the Channel frame bends. OVER the axle, is different because your bending moment is negative.
Honestly, a good web to web connection with clip angles or will give you a lot of the capacity that I believe you are looking for.



This is how bridge diaphragms are installed these days. They've found out that fatigue life of gussets and cover plates on flanges are at best, 1/10th the fatigue life of a bolted connection.
Click to expand...
Using clip angles how would you have attached them? Cut the clip angles square and just weld the top and bottom, or round the corners and weld three sides since it’s centered in the web?
 
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