Aluminum vs. Steel construction

[mjendrejcak]

I have a chance to buy a used gooseneck trailer, one is steel and the other is aluminum. I have always heard aluminum trailers do not flex but rather bend or crack. This confuses me since I see many big rigs dragging aluminum flatbeds that seem to flex and many RV’s have albumin skeletons. I would prefer to go with the aluminum trailer since I gain about 1100# more usable payload. The trailer is some aluminum alloy if that makes a difference.



Any opinions?

 

[csevers]

Is this trailer a flat bed or cattle or enclosed

I have never seen a cattle trailer NOT crack some/every where, all the of those trailers also had no suspension at all, just the flex of the tire side walls. I personally wouldn't buy a alum trailer with out buying a welder to go with it, but that is just me. I once priced out a featherlite 32ft tandem dual wheel g neck flat bed in aluminum at 13k similar steel ones were around 7k. It is no doubt lighter but I think will need more help down the road. The other thing is that the alum trailer I have seen have a steal neck and where they join the alum to steel is bound to corrode because of the chemical reaction.



Craig

 

[DPelletier]

Aluminum is nice in that it doesn't corrode and you get a higher payload, however steel is much less likely to get stress fractures or suffer from metal fatigue. Class 8 trucks use aluminum trailers because they need to have the highest payload possible. Period. They cannot afford to be concerned with how long the trailer will last. same reason tractor trailers use aluminum wheels, tanks, dump boxes, etc.

my 2 cents

Dave

 

[fbaurley]

In Metallurgy its called fatigue strength. a steel structure( if properly designed can go through flexing for an infinite amount of time, and still retain its strength and not fail. Aluminum on the other hand will eventually fail. It may take milllions and millions of cycles that would take 100 yrs, but it doesnt have the fatugue strength that steel does. This is part of the reason airplanes are scrapped so regularly, due to wing flex, because eventually they all will fail.

 

[mjendrejcak]

Thanks for the replies.





The trailer is all Aluminum constrution neck to tail. It is a deck over flatbed with slipper spring suspension. Rated for 12k gvw.





Sounds like the steel one is the winner. thanks for the info

 

[JThiessen]

I wouldnt go with the steel...

I didnt hear anyone chime in with actual experience with Aluminum trailers. My dad has been using and all aluminum cattle trailer along side his old steel one. The aluminum trailer has held up very well over the last 18 years of use. And its used regularly on an eastern Montana cattle ranch. Yes, they BOTH have had to have minor welds and repairs done on them, but they have both types of welding equipment available. Dad claims he'd buy aluminum over steel again in a hearbeat.



I work with both steel and aluminum in the aircraft industry on a daily basis, and have RARELY seen catastophic failure due to corrosion from the dissimilar materials coming in contact with each other. There are many anti corrosion products (primers/paints) available that are used where these parts meet. Remember, these units werent just slapped together without an engineer designing them for their intended use. The trailers are designed to be used up to their rated capacity (and a little more!) on a daily basis. Your NOT likely to see fatigue failures more from aluminum than steel.

 

[fbaurley]

If designed properly, you shouldnt see aluminum fail from fatigue, but put the same peice of aluminum on a fatigue testing machine and run it for thousands of cycles that greatly exceed the designed specs and the aluminum will fail from fatigue eventually. faster than the steel, even though if loaded the peices would fail at the same weight rating. Strength is not strength. It depends on the application, loading, and cycling. It has to do with the modulus of reselience. In lay mans terms you wont break your aluminum trailer from puting the weight on it, but each time you pull on the highway and the trailer twists from jumping up on the pavement it is going through fatigue. But it should be built heavy enough to do this for many thousands of cycles

 

[mjendrejcak]

Is there different grades of aluminum, one being better suited to this type of application? A visual inspect of welds and stress points looked ok, anything else to look for structurally?







The used trailer I'm looking at is the 24' model on this page

http://www.cargo-trailer.com/frames/felling-frame.html

 

[csevers]

I checked out that link. Sweeet trailer. It looks like a single neck? I like not having a v neck in the way on my trailer and I think you can go some places that v necks can't just due to the tip of the trailer neck. I am sure that trailer is WAY out of my price range.



Craig