Recently bought a 1970 Fruehauf low boy trailer. Running Historical Plates. I am in the process of Permently mounting , for a running display at truck and engine shows, 2 12000 pound engines. What are the rules on welding or bolting to the top side of the 2 main I beams. I recall no holes allowed to be drilled on the top I beam flange. Is this correct? Am I allowed to weld to the top of the I beam flange? Maybe I should use long U type Bolts instead. I have 5/8" chain maybe but cannot assure of being a grade 70. New at this type of transport.
Pics to help explain what I am trying to do. Mount this engine to the trailer
It is not best practice to weld across the face of the beam. If you can weld your brackets of D-rings length wise above the centerline of the web would be best. This is off course.... that we are assuming you do know what you are doing with a welder.
don`t think I would weld on the beam but I have mounted several large compressors to trailer beams by drilling & bolting at equal distance on each side of center . have not had any problems with beams or regs.
I would be a "U" bolt person myself, either make them yourself or go to a spring shop and have them make them. That would allow you to change your mind in a year or so...
When welding on a beam, the first rule is "Never weld crosswise". If you must weld crosswise, first weld a reinforcement to the beam, welding lengthwise. Do not weld the ends. Then weld crosswise to the reinforcement. Your filler must match the parent material. If the beams are T1 you will need preheat.
Welding or drilling the top flange isn’t that big of a deal if done properly. The bottom flange is a big NO-NO as it sees the stress in tension. Top flange sees it in compression. Can you build something that bolts or welds to outer beam flange that the engines can attach to? There’s a lot less stress on the outer beams than the inner main beams. Either way it’s not the end of the world if done properly. I’ve had factory build trailers with D-rings welded to the top flange. Also had them with key slots cut into them. Unless the trailer is in danger of being overloaded I see no issue.
How about a sandwich. One piece of plate 2-1/2" wider than the beam. Two pieces 1-1/4 wide as thick as the top flange of the beam, Two pieces 2-1/2" wide. A three decker sandwich bolted together to clamp to the top flange. I would use rustproofing grease, or Lexel between to prevent water being trapped between the layers. Weld till you drop to the top layer, no weakening of the beam.