Is floor frame construction method same for both Silver Streak and Avion?

[M2HB]

Originally Posted by SSSabre

Yes, the main frame rails are structural C channel. The channel profile is identical to the attached pic.

The structural channel is a great product for trailer frames. I have built many trailers over the last 37 years and I have used both structural channel and rectangular tube. I went to structural channel almost exclusively because of the strength and it's properties when welded. The advantage to structural channel is that the cross members and outriggers (if used) attach to the same piece of steel. Another advantage is that it has a square corner where the flange gets thicker as it goes toward the web. This makes it extremely strong. You get a lot more warping out of welding the tubing than the channel. If you weld the axles onto the bottom of rectangular tubing, when you remove the trailer frame from the jig, you will usually see a "bow" in the frame. To fix it, you need to put a "diamond" heat on the opposite side of the tubing. When welding the metal expands, and when it cools, it contracts more than it expanded. This shows up really bad on the rectangular tubing. Because of the shape of the flange, the structural channel doesn't do it as much. The reason trailer manufacturers would use the tubing is because it is easier to attach to the top of it with screws. Pound for pound, I would give the advantage to the structural channel. In order to bend either piece of steel you need to compress one flange and stretch the other. The structural channel is thicker where it needs to be, whereas rectangular tube is the same thickness all the way around. When building equipment trailers, most manufacturers use structural channel and when they build real heavy trailers they will go to "I" beams. Rarely will they use rectangular tubing. My Avion 34' trailer has a rectangular tube frame and it is one of the best in the industry, but I think they used it for the ease of manufacturing. Cutting cross members into the top of structural channel takes time because they aren't square cuts.

SSSabre, the reason that I asked the question is that I couldn' tell if the frame was a "C" Channel or a "Structural" Channel. The structural channel is much stronger.

[TXiceman]

Check your basic statics design and the inertia Moment for the different structural members. The rectangular section will win for stiffness.

Ken

[M2HB]

I was referring to practical application for trailer frames. The standard 6x2 rectangular tube weighs 9.42 pounds. Standard 6" Structural channel weights 8.2 pounds. They both have a 3/16 web. The rectangular tube obviously has two of them. The structural channel has a flange that is 13/16" at it's thickest point whereas the rectangular tube is only 3/16". This is the reason that they bow from welding so bad. This is from extensive experience. To compare the closest weight the medium 6" structural channel is 10.5# per foot and has a 5/16" web. If I wanted to compare strength for trailer while using the same weight, I would compare 6" rectangular tube to 7" structural channel since they are both about the same weight. The 7" structural channel has a maximum flange thickness of 7/8" There is another advantage to structural channel in the fact that it can be coated for rust protection. Trying to coat the inside of tubing isn't that easy. I don't worry about that where I live, but in some places, it is an issue.
I built a very complicated 5th wheel style trailer, with a dolly, earlier this year where I used channel and tubing. I still used heavy channel for the main frame rails. Most of your semi trucks use channels for frame rails. Most equipment trailers use channels. The heavy trailers use "I" beams. Both steels, rectangular tubing and structural channel, can be used to build good trailers. My Avion has rectangular tube and I'm very happy with it. Having said that, if I were building a new frame for an AS trailer, I would use structural channel. Maybe it's just a personal preference, but I have had very good luck with it.

[TXiceman]

I am not going to get into an engineering argument with a non-engineer of the basic statics and loading of beams. There are plenty of text books out there which explain the basics.

I have worked with the design of structural steel bases for heavy equipment. The design of the trailer frame is a piece of cake. The 2 x 6 rectangular cost more than a 6" C section. Some places a C channel is easier to work with, others a box section.

Have fun down the road.

Ken

[alisharae]

I know this is an old thread, but just curious...how do Streamlines stack up against Airstream, Silver Streak and Avion?

[jonplayers]

Why not throw Travelux in there too?

[slowmover]

Streamline was a corporate split from Silver Streak so it is likely that these two brands are the most closely related. Frame may have been better, and the interior aluminum cabinetry was superior to any other trailer manufacturer (fatigue strength, lightest weight, longest life).

I would include Travelux, but even among those of us with some vintage kin experience, this was the lowest-production, thus least known brand. I've never seen one in the wild. Those owners are invited to post a pic or two of frames to this thread, and links as well.

[Ganaraska]

You ask about the Travelux. I have one. It compares most closely to an Avion from the sixties. It has a frame with 3 long rectangular frame rails,2" X 5" deep, with crossmembers arc welded every 24" and two conventional, leaf spring axles.

5" insulation under floor. Full belly pan. Micronite insulation in walls, same material used in modern planes (quote from brochure).

In general construction is sturdy but some details rather crude or home made looking. I put this down to the low production and the amount of hand work required. Appliances, fitting etc. all standard off the shelf parts.

I have the 25 foot Princess model. Weight, according to factory brochure, 4400 lbs. They also made a 29 foot President Elite, 4550 lbs and a 31 foot President, 4780 lbs.

All reports indicate they were strong and durable. Some owners used them for years with no major problems.

I have the owner's manual that came with mine in 1971. Inside front cover is a Lifetime Guarantee.

When you read the find print they guarantee the trailer against defects of material and workmanship for life. Does not include tires, brakes, appliances, etc etc anything not made by Travelux, or vinyl covering or exterior coating. Tires, appliances etc. are covered by their makers' guarantee.

All repair claims must be made at the factory.

There is a place for the serial # and the dealer's and owner's name but the way I read it, the guarantee is for the life of the trailer.

Mine has outlived the factory by about 30 years so far.

[jonplayers]

Yes they are a rare bird. They most closely resemble the early Avions. They had a fairly well built frame...at least mine has. Three runs of 5"box steel with 5" C steel every 24". The channel on the floor (where the shell is fastened) was a little wimpy. As were the fasteners (3/4" screws) holding the Chanel down. This resulted in front and rear end separation. The plywood is fastened well to the frame though.

A couple of interesting Inovation's not found on there siblings would be thick butyl tape on all the ribs (between the exterior shell and ribs) as well as the segmented end caps (between all the segments). I am hoping the tape on the ribs acts as a thermal break. They also have weeping holes every 6" in the floor channel.

[Ganaraska]

jon is the body mounted to the frame, then the floor plywood laid in, or is the body mounted to the floor and the floor to the frame like an Airstream?

[jonplayers]

Yes it is like an airstream. Just a little beefier frame.