# Trailer design

1. May 14, 2012

### sgmech1

I am working on designing a trailer that will hold a load of 350lbs on 2 centered posts. It needs to have a safety factor of 3, so 1050lbs plus trailer weight. I am trying to determine the size of Steel square tube I must use. Any advice on formulas or methods of determining this? I would greatly appreciate it.

Thanks

2. May 14, 2012

### sgmech1

How would I determine the shear stress on sqaure tubing if I am using ASTM A500 Grade B steel

3. May 14, 2012

### Mech_Engineer

Without some better specifics for your geometry (like a picture) it's hard to give you any useful feedback. Remember: a picture is worth 1000 words.

4. May 14, 2012

### sgmech1

What formulas are there for shear if I have a yield point of the material?

appreciate the help

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5. May 15, 2012

### Mech_Engineer

Why is load of the trailer supported by just those two points, instead of distributed accross the trailer's frame?

6. May 15, 2012

### Travis_King

I'd imagine that it's for something like a jet ski. Most of the weight will be directed on the two keel supports. There will be side supports to keep it straight probably, but they won't bear much load.

Is this for a personal or academic project? If it's personal, then just over design it. If it's for school or something, well, just look up "bending and shear in beams", "shear at welded connections"

7. May 17, 2012

### nvn

sgmech1: (1) What is the distance between the centerlines of the tires? (2) What is the distance from the back tube centerline to the trailer hitch ball? (3) What is the distance from the back tube centerline to the front load point shown on your diagram? (4) What is the distance from the back tube centerline forward to the apex of the diagonal tubes?

Last edited: May 17, 2012