Chassis Design

[Obsessed2findARuggedHybid]

I am trying to understand which of so many different chassis designs out there are the most rugged for off road trailers. I have attached two pictures one is an aluminum C channel chassis with multiple cross members. The other is carbon steel closed tube powder coated with very few cross members. The steel chassis is a foot narrower and two feet shorter. Both are from trailers that have a 3,500 pound gwr. Which one will hold up better?

 

[NatersXJ6]

With or without corrosion?

The chassis life is all about loading and twisting assumptions and a whole lot of beam bending calculations.

It is probably fair to say that the Aluminum one is likely lighter, more expensive, less likely to corrode, easier to clean, and harder to field repair than the steel one.

I wouldn’t think there is a definitive “better”, “stronger”, or “longer lasting” measure between them. They are simply different ways to accomplish similar goals.

 

[Obsessed2findARuggedHybid]

Doesn't more cross members strengthen the frame regardless of metal type?

 

[plh]

C channel works great as it is more flexy than a rectangular tube. I'm reprovisioning a Northern (Ironton) 5x8 C channel steel frame for my base.

 

[Obsessed2findARuggedHybid]

Yes my builder is a big fan of C channel.

Does c channel aluminum require more cross members then boxed carbon steel tube would?

 

[NatersXJ6]

It all depends on the size, thickness, loading. There is no easy black and white answer. The number, size, location of the cross members will determine how twist resistant the trailer is. At that point, I’m getting too far over my skis to give you an answer without reviewing a heck of a lot of books.

 

[OldGreen]

Until you put stabilizer Jack's down... single axle trailers do not really twist a whole lot from the loads that come from the ground. If you use jacks, level the trailer first and just use the jacks to keep the cabin from rockin...

For construction, everyone has already pointed out the two schools of thought...engineered AL and overkill steel. Mines steel. 50k HARD miles on and off road later and it hasn't budged. 2100lb dry. Around 3k loaded for a month in Mexico.

 

[gatorgrizz27]

People will disagree with me, but aluminum will crack over time given rough terrain (even washboard roads), and enclosed steel will rust out from the inside.

Steel channel is the ideal frame material IMO, though it isn’t as light or torsionally stiff as other options.

 

[Teardropper]

People will disagree with me, but aluminum will crack over time

I'll go so far as to say it depends on who designed it and who fabricated it. (You may be right! ) But why risk it? The steel trailer won't crack.

Tony

 

[Obsessed2findARuggedHybid]

Good point. I believe if the correct alloy and gauge of alum c chanal is used the risk of cracking is reduced. Is the concern in the welds cracking or the actual c Chanel? Of course it just all depends on how fast you drive off road.

I would assume carbon steel tube corroding from within. Might cause cracking or snapping.

Aren't most flat bed semi trailer chassies aluminum?

 

[plh]

Good point. I believe if the correct alloy and gauge of alum c chanal is used the risk of cracking is reduced. Is the concern in the welds cracking or the actual c Chanel? Of course it just all depends on how fast you drive off road.

I would assume carbon steel tube corroding from within. Might cause cracking or snapping.

Aren't most flat bed semi trailer chassies aluminum?

Poor welds of aluminum is generally where it cracks. It is much easier to create a crap aluminum weld than a steel weld. Hopefully semi trailer manufactures are using pro welders (or robots)

 

[Teardropper]

I would assume carbon steel tube corroding from within. Might cause cracking or snapping.

If you weld the tubing shut, it won't appreciably rust inside. Or live in a low-humidity environment.

It was common with aircraft with frames made from welded tubing that the major pieces had some linseed oil added to them before they were sealed off. A crack would show when the oil began seeping.



Tony