Stuctural Angle Load Capacity

I expect that Matweb or some other sites have this available.

I have a car hauler and I just measured the ramps on it. They are constructed as you describe above.

They are 7 feet long and the rails are 2.5x2.0x.218 inches thick. I've loaded some 6,000+ pound cars with no problems. A mid 70's Chevy wagon caused no problems, neither did an 85 full sized Blazer.

Good luck.

I agree totally with redfred. You cannot expect a responsible answer from a public forum uch as CR4. Suppose I give you advice which results in the collapse of your structure. What are you going to do, sue me? Get real, man. This site is intended for the discussion of ideas, not specific designs. If you were not aware of that prior to this, be aware now.

GA for RedFred...

Best to buy a ramp that's factory manufactured, load tested, and certified than to build one without a professional engineer structurally designing it (and performing no load testing)....there's too many unknown variables to consider in this forum posting to safely rely on. You won't find me under your vehicle while it's on a homemade ramp, that's for sure!

Totally agree with redfred-

For the relatively few bucks you would save building you own ramp- BUY a proven safe one.

I have the structural specs for most angles- use them for pipe hangers, etc. but I would not trust my car or my life to a ramp that I built vs. one that had certified construction.

As a rule of thumb for home design - beware regulations for business use - I'd look at what is available retail and decide if I could source higher spec parts and weld up for less than or the same price.

Most ramps are built to minimum specs, so by creating something which is of thicker material, and/or with the next size, an additional safety margin should be built in.

I say should, as this depends on how well the welding is done as well as the type of steel used.

For only 12" a wedge of timber wider than the stand should suffice - railway sleepers are easy to find. The compressive strength of timber is amazingly high.

The critical issue for "copying" an existing design with higher strength materials is to truly "COPY" the design. thicker angles may have little value if you forget to install the sleepers that prevent twisting of the angles under load- totally destroying any structural capacity.

A safer way to make home made ramps would be to layer 2 x 10 or 2 x 12 planks till you get to the height you want (2 x 10's up to 8" high, 2 x 12's up to 12" high). You end up with solid wood that won't crush, probably even under the weight of a tank. Certainly enough for a class A motorhome. Mount a couple of handles on the side for carrying.

I'm still not comfortable with this idea. I agree that crushing will not likely be a problem and I'm also certain that you, Jaguar, can assemble this ramp approach in a safe sturdy design. But you assume that the surface is flat and level. You also don't specify how the planks will be fastened to each other to prevent them from slipping apart.

We all want to help people who come to us with their design problems. That is one of the reasons why we spend time here. But somebody is asking how to fabricate one of the oldest simplest machines known to mankind, the inclined plane. This machine will be controlling very significant amounts of energy well above any safety threshold. This comes under the heading of if you have to ask how, you're not qualified.

Yes!! Right on redfred. Inclined planes are capable of causing serious injury and death.

Every inclined plane having any dimension greater than one meter should be properly marked by an approved safety warning sign. All such inclined planes should be subject to either municipal building code regulations or applicable safety agency approvals. (see below for the special case of "high mechanical advantage" inclined planes)

Design and specification of inclined planes over one meter should require suitable engineering calculations and signature and properly sealed certification markings by a licensed professional engineer.

Construction of inclined planes shall be conducted under the supervision of a licensed engineer who shall provide the final approval prior to its being put into service.

All inclined planes covered by this regulation shall be inspected at intervals of no greater than one year for continued conformance to engineering specifications and a report of that inspection placed on file by the approving agency.

With respect to possible illicit and unapproved construction of inclined planes out of common lumber materials it is recommended that all citizens receive a minimum of 4 hours of instruction in the identification and proper use of nails for fastening pieces of wood lumber together to insure that such devices are rendered less capable of unexpected and catastrophic failure as observed and reported by an alert CR-4 member.

Special Case of Inclined Planes of High Mechanical Advantage. Because of their ability to multiply force to amounts greater than 10 times such devices require special consideration. Therefore any inclined plane of angle less than 5.7 degrees and dimension greater than 250 centimeters shall also be subject to this regulation.

After much careful consideration of the issue of excessive force multiplication it is strongly recommended that inclined planes of angles less than 1.14 degrees never be constructed as they are capable of force increases up to 50 times or more.

This particular issue raises some serious concern among those responsible for public safety. The possibility that an inclined plane with an angle of a small fraction of a degree being created and the resultant mechanical advantage thus created being capable of forces in the range of thousands of pounds and even tons should give serious concerns about allowing certain fabrication tools to get into the hands of those with malicious intent. This is an issue that should be of grave concern to all of us.

Ed Weldon

Line 6 under the drawing states assemble with spike nails. I didn't include it but if the constructor chose to use carriage bolts with proper countersinking and back-up washers, that would be acceptable.

I understand that many people are not capable, without further instruction, of swinging a hammer in a manner to extract maximum advantage, but most should be able to drive a large, 4" or longer, nail, even if it takes them more than three swings for each nail. Of course, it should be built up in layers. I wouldn't think anyone would try to stack multiple layers up to 12" and try to drive a few 12" spikes to connect them. (maybe in an industrial setting with presses but we're talking home built here)

Precautions about safety are all well & good, but asking a question does not prove one incompetent to receive an answer.

whats more dangerous a badly designed ramp or badly placed jacks or jack stands?

what are the modes of failure for each?

personally I've had far more near misses with jacks then the other 2

a pile of wood stacked & suitably joined [lets not forget my favorite torx head deck screws] is probably the safest option.

The OP was interested in the math involved so he could better understand the existing common ramp design

doing anything on the internet requires due diligence, we should error on the side of more information not less...