Looking for feedback on design for HMMWV cargo cover and troop cover bows

[Bulldogger]

Any person who has a HMMWV that has wanted to fit a cargo or troop cover where there wasn't one when it came into his or her possession has had to either look locally and hope for a set of bows or order them and pay extra shipping fees due to the oversize package restriction. In some cases Less Than (full) Load (LTL) truck freight might even be involved, at a hefty price.

I have been learning to bend 3/4" steel light wall tubing as part of building HMMWV Soft Slant Back kit frames. I've also started making 4-man cargo covers in sailcloth for folks that have gone aftermarket on their tops and want a cargo cover to match. Some of those customers have asked me if I sell bows, which I do not, partly because sources exist and because sourcing, storing and shipping 7' wide bows is a PITA. So, I have been thinking of developing an alternative design or designs for HMMWV cover bows.

Based on my experience with thin wall steel tubing (Electrical Metallic Conduit, EMT, mostly) I am also aware of many commercial fittings available for this type of tubing. I use a few in my SSB frame already.

It seems to me that I could bend the 90deg portion of the bows pretty easily, but instead of doing it out of one piece, or welding or whatever, I could make it modular.

The idea I have is to make the bends in a piece about 4' long, and make four of those, and have the whole mess joined with some straight pieces using EMT couplings to get to full size. This would not be as strong as integral 15' long tubes of course, but all the bows have to do is hold up 20 pounds of canvas. If someone wanted more than the set screw that couplings come with, it's easy enough to put a couple self-tapping screws in there. Some of my customers like that, and I include 4 of them with SSB frames already.

I think the shipping box would be about 4' long and 9"x9" square. That is still over 36", and will have some oversize penalty, but far less than 7' wide 4' tall bows.

After all the bending and cutting and mockup, adding tie down straps and drilling holes for the fender brackets (and buying fender bracket kits to have in stock if needed) I think the price would probably be the same as military surplus bows, the difference would be in the shipping costs.

I wonder if folks think this is worth fussing with or just adding a choice to an already crowded market. I could probably sell some with cargo cover purchases, when the customer doesn't have them anyway, but I'd rather be in position to tap into a larger market of people just looking for bows and less expensive shipping options that my design should give.

Thanks in advance for your feedback!

Alex (Bulldogger)

 

[GuntherRommel]

The bends are no where near 90 on the 4 man cargo cover

 

[Coug]

EMT seems a little light to me, especially if you're going to put couplers in the middle of a longer span that will have rain and snow potentially collecting on top.
If the shape is anything like the bows for the troop carrier and 1102 trailers, then the top section has a bend in it as well, and the end bends are greater than 90 degrees to create some slope to the roof to shed water.

Possibly find some steel tubing with swaged ends, and combine it with long sweep elbows for the corners, and you might end up with a shipping box within your 36" standard shipping window.

 

[Bulldogger]

Agreed, to you both. The tubing may be too light. I will make some measurements with calipers on the bows I have. Easy enough to figure out the wall thickness. Yes Gunther, the bends are not 90deg exactly. I have a protractor I will use to measure the angle before I replicate it, if I undertake a copy. And good point about the slight bend in the center to give a peak, I noticed that.
I don't plan to add turnbuckles either, as every set of bows I have seen in person has these broken off anyway. Not a copy, an alternative.
Swaged ends for the tubing joins would be strong, but might also be a chore. I do not have the kind of tooling to do it at home, and no other need for it otherwise so it's not a wise purchase. It would be wise to figure on some snow load, as that happens. I use PVC internal coupler to align soft slant back frame joints between tubes, combined with an external clamp. If I switched to a split metal piece if tubing that would give more strength (sort of like a roll pin in appearance, I don't know the machinist's term for that, maybe split tube internal coupler?). PVC does add some strength as it is.
At some point I'll have to just mock one up or keep guessing.
BDGR