Not relative to trailers, but it seems the box frames are being used more and more on HD pickups. The 2011 GM's are box, right? And Dodge for the past several years. Do you think this is because the boxes can be made lighter weight, cheaper or maybe both? The box frames seem to sometimes complicate installation of hitches and other accessories. I think I may have read on another web forum that the early B&W hitches for the 2011 GM's have had some structural issues.
Load in Truck vs Load on Trailer
- Thread starter Harold_J
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Diamondpilot
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The main reason to go with a box frame is strength without adding height. That is very important on the new 3/4 and 1 ton trucks. Many will not fit in a garage as it is. In just 10 short years the tow ratings on a 1 ton truck have went from 14K to 24K. Something has to give and to keep ride height and strength in check a box frame is being used plus its just strong.
The manufactures of these trucks do all they can to fight off rust. Trailer manufactures do very little and there lies the problem.
Chris
Egon
Epic Contributor
The difference between the use of Box or C channel may be section modulus requirements and overall weight of the frame member.:thumbsup:
Renze
Elite Member
You get the most bend strength out of a beam with most of its meat on the outer sides: like a C channel or I beam with heavy upper and lower flanges, and a thin vertical flange: bend force consists of compression in the upper flange and tension in the lower flange: the center doesnt do a thing actually. its called the neutral line.
However, a truck chassis as described above, might be very capable of carrying static loads, but it twists all over the place when under the dynamic, alternating loads on a road chassis: To get a more rigid frame with better handling, less body roll, less sway, etcetera, tubes are used because they handle torsion a lot better: the torsional resistance of a beam consists of the bend resistance over the X axis and the bend resistance over the Y axis: The I and C beams have very low lateral bend resistance because again, all the meat is in the middle, where it does nothing.
In Europe, Iveco (a Fiat division, made in Spain, historically notorious for their rust) claims that their C channel frames are less prone to rust. Mercedes (famous for their German anti rust treatment) uses a box frame, rust isnt an issue, and they have the most comfortable undercarriage which handles like a car, because of the overall rigidity, less body roll, less sway.
The difference in trailer building is that standardised, off-the-mill C and I channels are about 1.20 euro per kg: square tubing hits 3 euro per kg.
Especially in lighter trailers, the wall thickness of the I or C beam flanges are so thin that they flabber all over the place: thats why i build them out of trussed tubes. It sways less.