Do you think this would be strong enough???

[kanoa9321]

I am building ramps for my trailer and will be making them out of Aluminum, but I am not sure if my idea is strong enough or maybe even over kill(I doubt it).

To get an idea the race car weighs 640lbs on each front corner, so each ramp will only have to support 640lbs, since the front and backs will never be on at the same time.

I was originally thinking of going the standard route of some square tube and making a ladder type arrangement, but then I started thinking.

If I use 1/4" X 3" flatbar on edge for each side, then every 12" have a cross member of 1.5" X 1.5" x 3/16" angle connecting the two pieces, and then I will top it off with a piece of 1/8" Diamond Plate to give a smooth role up. Do you think this would be strong enough to support my load. The ramps will probably be 5ft long X 12" Wide

I have included a drawing to help understand my idea. Is their anywhere that I can find out how many pounds a piece of 1/4" X 3" flat bar on edge can support over a 5ft span? Keeping in mind their will be no constant wait on the ramps jsut simply drive up and down.

Thanks in Advance

[MAC702]

What's your safety factor? 2:1, 3:1, etc. ?

[kanoa9321]

Sorry what do you mean by that? How many lbs the ramps would break under compared to the laod I would be using them at?

[MAC702]

Yes, you don't design a ramp to hold 640# when you expect to put 640# on it, especially when it's rolling and on suspension.

Hank's got a good suggestion in this thread on the other forum, though. These things are probably easier to buy than make, and that means an engineer has approved the design already. Seems that 1000# ramps aren't all that expensive.

[Thormold]

I bought 1000 lb rated Aluminum ramps on Pep-Boys on sale for $89 (long time ago). My best friend bought them last week on regular price for $139. These ramps are tri fold (Three leaves attached together and fold one on top of the other) and the weight calculation is distributed between the three leaves. I'm quite sure you can find two individual ramps that would carry the combined weight of your car. Sometimes is easier to buy than to built. If you already have the materials, go to the store, look at the ramps for ideas and make one yourself with improvements.

Thormold

[lotechman]

You have considered static load but when the car hits the bottom of the ramp the momentum could put double the load on it.
A commercial ramp would be a better way to go but if you are going to build your own:
The side pieces should be something like 1/4 by 3 by 3 angle with the leg hanging down for maximum stiffness. The cross angles you have drawn are also incorrect. They should be arranged so that the leg hangs below rather than sitting against the underside of the plate.
The cross angles should be properly coped to fit into the angle side rails.
The idea is to get the neutral axis of the angle pieces well away from the top checker plate of the ramp to provide maximum stiffness.
Tube side rails and 3 inch cross pieces would be better. This adds up to a lot of dollars. Aluminum took a big jump in price in the last year.
I just got off an aluminum catwalk job. It used over 40 tons of tube ranging from six inch square to 2 by 4 for handrailing.
I got pretty good with a skill saw.