Any engineers in the group?

A

Andrew Holley

Well-known member
Still gathering pieces to build my trailer and also keeping an eye out on ebay for used trailers, which is where I found this one.

trailer.jpg


This is the second or third time I have seen the "bridging" welded on top of the side pieces, does this give it that much more support? Seems like a lot of work and maybe just thicker steel in the main tubing might give it just as much support? Now the total length of this trailer is going to be close to 30'.
 
I'm not an engineer but I stayed at a Holiday Inn Express last night...well I really didn't even do that...

The bridging as you called it dramatically increases that strength with far less metal (and therefore weight and cost) than if you were to mearly use one thicker, bigger dimension channel of steel. It is the same principal as an I-beam really.

Chuck
 
strength wouldnt be as big an issue if the wheels were in the middle of where the most
weight is ,is it single or double axle ,double would be better.,better weight distrubution.
i think anything you can do to keep the tounge weight down is good ,you may need them helper things that
put pressure on the ball and stops it from fish tailing on ya,we had a 20 foot camper trailer
do it to us until we put on them things i cant for the life of me remmember there proper name,brain fart!

looking good keep at er
 

The trailer you posted looks like a home built job to me.

If labor costs were a concern you'd think would want parts you could bend/form, not do all of that welding. Labor time costs money. I find it hard to believe the materials savings in the design you posted would make up for the increased labor costs in a production setting.

I was at the Boston boat show last week and noticed that the big aluminum trailers tended to be made of aluminum I-beams.

Charlie
 
Assume that a trailer is a simply supported beam uniformly loaded. It's not, but assume that.

The amount of bend in the beam is dependent on the length of the beam, the weight applied, the modulus of elasticisty (the strength/stiffness of the material) and something called moment of inertia.
maximum deflection at the center of the beam is:​
(5 W L^3)/(384 E I)​
​
By welding the bridging on the top of the beam you make the moment of inertia bigger therefore making the deflection smaller.​
View attachment Simply Supported Beam.ppt
 
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