I need some engineerin'.

So here's a thing.



The horizontal sections are each 4 foot, so six foot from the outside to the center of the vertical section.  I forgot to put it in the sketch, but the sides of the central box are 2 foot, leaving 5 foot from the horizontal surface to the top of the vertical section.  I want to support 600 pounds at the outside of the horizontal sections by chaining them to the top of the vertical, independent of the other side, so no fair balancing the sides against eachother.  How strong does that vertical section need to be?

I'm not sure that strength is going to be your biggest issue.  Yeah, you'll need a decent sized column in the middle, but I'd be more concerned with how you're going to anchor that column to the floor.  The load placed that far out from the center of the column will create a torque load on the column, wanting to pull it over.  Do you know what angle the supporting cable/chain will be at? If you can give me a close estimate I'll be able to tell you the vertical and horizontal components pulling on the column.

I assume this is for your camping trailer right?  Why support the load from the center as opposed to underneath the horizontal sections?

Because this way all I need to do is level the trailer. If I support from underneath I have to worry about leveling the supports too, and that's a PITA.

The vertical column needs to be collapsible so I can fold up the tent. My first idea was to weld a piece of 1.5" receiver into the body of the trailer, and run 1.5" inner hitch steel as the vertical. I'm pretty sure that I could put 600 pounds on the end of a five foot chunk of hitch steel without it bending, but I'd rather not have all that weight if I can help it?

According to this, with a 6x5 right triangle, the angle at the top of the vertical is 50.2 deg and 39.8 at the edge of the horizontal.

I think you'd be fine with what you're planning on doing it, just make sure it's secured to the floor pretty good. Maybe add some small gusset plates where you weld to the floor of the trailer.

What are you adding that you think will be 600 lbs?

dutchman wrote:What are you adding that you think will be 600 lbs?

Nuthin', that's just my safety factor. I figure the most load it could ever have would be two adults, 500 pounds max, and that would be evenly distributed. So if I build for 600 pounds at the very edge, I'm good, right?

600 lbs at the very edge would put the largest torque on the column, so in theory you should be good.

Will the hinges where the panel folds out hold up to that weight? What about the panels themselves? Just trying to think of other possible weak points.

The panels will be 3/4in plywood, maybe 1in. It's currently built with piano hinge riveted along the length of the platforms, but that's a little flexy so I'll try to find some thicker stuff.

I guess there is no 1.5" receiver, just 1.25". Is there any way to calculate exactly how much weight that could support?

Do you know the wall thickness of the 1.25" receiver?

Hrm. No idea, on the receiver or the inner hitch steel. You kinda need to know that, huh? Lemme get back to you.