Feasibility of retrofit dovetail on 20' flatbed gooseneck trailer

Greetings,
I recently acquired an old 20' gooseneck flatbed trailer. It's spent the last 10 years of its life running around a hayfield.
We are re-wiring and repainting it. Since my main need is to haul vehicles on it I'd like to retrofit an appropriately sized dovetail ramp on the back.
Has anybody here every done that? Are there any D.O.T. or other design / engineering issues? I'm aware that there is some magic juju as to axle placement on a trailer. Will the addition of a dovetail require changing the axle position?
Is there anything anybody wants to mention I haven't been smart enough to ask?
This trailer is fairly high. I need to do something to facilitate loading and unloading vehicles on/from it. So, can I add a dovetail?
Or should I buy a Huey helicopter on ebay?
Vernon
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I have a 18' car hauler trailer that I took the dove tail out to make a flat bed for my quads. On mine the frame rails are 3x5x1/4 angle that was "V" notched 18" from the rear to create the dove tail. On the off chance that I have a car to haul, I made up some 8' ramps.
The whole thing was easier than I thought it would be.
Best of luck
Stu

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Were you planning on adding a dovetail to the end or notching and welding the back 4' or so into a dovetail? Adding to the end will mean looking at the frame rails going to the back of the trailer to make sure they are strong enough to take the bending load that far away from the axle. Cutting, notching, reweld may be easy or hard depending on the configuration of the frame rails. This would certainly call for adding suitable fishplate reinforcement as well as high quality welding. I'd also make sure that the frame is not some sort of high strength heat treated steel. (somewhat unlikely since most trailer mfg use common hot rolled steel shapes)
Axle placement is a function of where you place the load and how much load on the wheels vs gooseneck. Seems to me you need something like 25% of the load on the gooseneck (????)
Vernon wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks to all.
Roy: Your comments were especially thought provoking. Maybe I'll take some photos, post 'em on my web page, publish the links, and ask for additional comments from everybody.
V
RoyJ wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Glad to get the juices flowing! And it's usually called a 'beavertail', not a 'dovetail'. My bad.
Vernon wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
What height is your deck?? I hope under three feet. A angle iron truss affair under the ramp will allow you to keep things light. Pics would certainly help. Randy
Thanks to all.
Roy: Your comments were especially thought provoking. Maybe I'll take some photos, post 'em on my web page, publish the links, and ask for additional comments from everybody.
V
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Randy,
Our digital camera went kaput. I only learned this yesterday. But I'll take some measurements and post 'em later.
I don't know the height of the deck but it's pretty tall. It's a 20' x 8' platform with no rails. Sits on top of the 16"? wheels. That's why I think I need ramps or a "beaver" tail.
We hope to get it re-wired this weekend.
V R. Zimmerman wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.