I need to add some things not previously mentioned. If you go look at the commercially manufactured trailers you can, or I was, very surprised to see things I would never allow, and that are unacceptable to me. The intent is to pull these trailers down public roads/highways, Safety MUST be a concern. I'm not including the names of companies but the one's I've seen are barely at or just below minimum safety standards to me. It amazes me that people are actually paying thousands of dollars for trailers that cannot possibly last more than 10 years and may well not make it that long or without serious structural issues. Getting up on these trailers and walking to one corner and jumping blows my mind, the opposite corner bounces up and down... Talk about flex!!! Wow! The next thing I noticed was the welds connecting gooseneck uprights to main frames, in some cases there are two single welds running down each side of uprights to main beams with no knees. The dovetails have two center supports only and some use 2x2 angle with 3/16 inch wall. (this is the self cleaning dovetail ramp material) Let me clarify... Tandem dually with 40" spacing between mainframe beams, 40 inches without support, how do we get to 8 feet or 8 1/2 feet (legal limit 102 inches) well to 8 feet which is 96 inches you have no support outside the main beams which are on 40 inch centers, so from 40 inches to 96 or 102 leaves 56 or 62 unsupported inches (varies due to actual spacing but tandem dually axles are generally on centers at 37 to 40 inches and the width of the beams must be considered) in essence you're looking at 34 or more unsupported inches between frame members and 24 or more inches outside frame members. (then the little 2x2 angle on top eight feet long!!!)
The ramps are connected and welded to prevent removing them. Reason? Because when the ramps are flipped over and lowered to ground they support the rear of the trailer by being on the ground, then the dovetail is supported from the ramps on the ground. Fine, but suppose a ramp gets damaged and the customer removes the ramps, then he does whatever he needs to do to get his product/ machinery on trailer. How will he feel when he over stresses the dovetail and/or breaks it off? (worse is hairline cracks and you know nothing, suppose it falls off going down the road???) Do you see where I'm going here? I don't like it. The tandem dually can carry more weight, they have higher ratings per axle and they have four wheels and tires per axle, but at what cost? With the required narrow frame therein lies your cost, higher center of gravity and narrower frame makes the trailer a lot less stable, depending on what you're carrying. Let's face it, we see these trailers traveling down the roads we drive on regularly, sometimes with bulldozers, backhoes, excavators etc.
How often do you see one of these trailers for sale that is over 10 years old? I see a few, but I do not see any of todays big name trailers with 10 or more years on them for sale. Why do you suppose? Why do you think a full steel deck on an equipment trailer is so rare? I'm guessing in order to prevent the deck from washboarding, they would have to use quarter inch plate (or thicker) because the frames are so weak.
Enough of the rant...
I'm using 3/16 inch diamond plate on my deck, 4 inch bedframe and crossmember channel on 16 inch centers, my main frame is 58 inches and each beam is 4 1/2 inches wide. Due to the aforementioned, I added a third main frame beam, a single 6 inch channel in the center, I contour cut the ends and welded into mainframe crossmembers, at the dove I doubled the channel again, welded it to rear crossmember, gusseted the rear crossmember then took 5 inch 3/8 inch wall angle and welded to both sides of dove center mainframe and rear main frame crossmember, I took another piece of that same angle and welded it to the inside of the mainframe dove sections and rear mainframe crossmember.
I'm getting ready to call Dexter and see if I can get 10 or 12K axles with 58 inch spring centers to run super singles like the big trucks and trailers.
I still have the option to add a third axle, though not my preference...
Another thing. The big companies use these huge gooseneck upright to gooseneck forward gusset plates, I believe these are to minimize flex at the neck. Not one to go along, I don't like all that flat plate getting in the way, I cut smaller almost unobtrusive gussets, welded them in that area then miter cut solid 5/8 inch rod and welded to upright and forwards and to gussets and I believe that will stop the neck flex better and look much better, I'll post results...
All of my bedframe and crossmember channel is cut, I'm waiting on a nice warm couple of days, to pull it all outside and finish. I will use the two 7k axles until a better plan comes along or out of my brain. I have the weight at about 6200 lbs currently. 25% on truck effectively removes that weight from trailer axles but in a conservative move, I'm saying 20% and 20% of 14,000 equals 16,800, subtract weight of trailer @ 6200 lbs and I can haul 10,600 lbs.
I am anxious to get it all on the big truck scales at nearby Pilot. I'll weigh truck connected to Goose and goose axle weight, then drop goose on scale and weigh it...
