engineering question

[WFE2-70 NWIA]

Bought a pair of ramps on a sale. Ramps are 6' long, sides of ramps are made of 1" x 2" x 12ga. rectangular tubing with expanded metal in between. With small 1" x 1/2" channel iron going across to support the expanded metal. Channel irons are spaced about 12" apart. My question is are these ramps heavy enough to support a front wheel drive car? Cars would be a 97 olds cutlass supreme and 98 Chrysler Concorde. Thanks for the help.
 

[Uncle Ernie]

They sound kinda light to me. Can you block them up mid span to take the weight in the middle of the ramp? Don't forget to block the trailer up in the back too if you do! Otherwise you have built a teeter totter for cars!(Dont ask how I know...)
 

[jon f mn]

I've built a lot of ramps and I would say no. That long they would much to weak. Like the other poster said, block the middle and rear of trailer and you might make it.
 

[Puddles]

Here is a chart, not quite what you want but may be close enough.
1”x2”x 1/8” wall square tube with a 4-feet span is good for 1,500-pounds uniform load. So point loaded in the center would be 750-pounds. Remember that is only 4-feet span!


 

[Indiana Ken]

Question: Are the 1" x 2" x 12 ga tubing pieces placed on edge such that the 2" section is in bending or flat such that the 1" section is in bending?
 

[retired farmer]

Kind of sounds like they are Harbor Freight ramps for loading lawn mowers and four wheelers. I wouldn't drive a car on them.
 

[WFE2-70 NWIA]

They are built with tubing the tall way, so it would
have to bend across the 2" way. I can put a truss
rod or strap under them to stiffen them up if
necessary. If I did this how far away would you
suggest I put the truss from the center of the ramp?
I know the farther away I put it the stronger it
will be. Thanks.
 

[jon f mn]

6 foot is a long ramp. As a general rule you can figure it takes double the strength for each foot of length. So a 5'has to be twice as strong as a 4' and a 6' has to be twice as strong as a 5'. So, if you can cut off a foot or so that would help. But if not you could take a flat and bridge it. I would go at least 4" or more for 6'. Once you put a bridge under it the bridge will be doing most of the work, so make sure it's strong enough.
 

[Stephen Newell]

I'm surprised the ramps don't have a load rating on them. You might see if you can find them advertised somewhere where I'm sure there would be a load rating. I think its a almost sure thing the ramps would fail. They were intended for a riding mower of 4-wheeler. If the tublar steel would hold up I don't think the expanded steel would. You never see a car carrier with ramps with expanded steel.
 

[Chris(WA)]

Would you post a link to this chart?
 

[JMOR]

End all the speculation! Drive on them & see if they bend.
 

[Puddles]

[Indiana Ken]

I did some simple hand calculations using 30,000 psi as an allowable yield stress. Since we don't really know what the material is, I assumed a non-structural 1010 steel. Also, we cannot be assured the vehicle will be centered on the ramps so I placed all the wheel weight on one of the 1" x 2" x .1046" wall tube members. The maximum stress occurs when the wheel is half way up the ramp. The yield stress level of 30,000 psi is reached at a wheel weight of approximately 500 lbs. That would mean the front of the vehicle could weight a maximum 1000 lbs, (500 lbs per wheel).

This is not to say the ramps will fail if the front of the vehicle weights more than 1000 lbs but rather to say the ramps are better suited for lighter vehicles.

To your question of reinforcing the ramps by placing a bridge under the tube on each side: If a 6" bridge is used and we assume a wheel weight of 1500 lbs, the tensile load in the supporting tie bar would be approximately 4,560 lbs. A 1" x 3/16" thick tie strap could be used with three bridges; one in the middle of the 6' tube (6" long) and one centered on each side of center, i.e. 18" from each end, (3" long).

I would very much recommend that you not reinforce these ramps since 4560 lbs is a high load to join with thin wall tubing. It would be best to start with ramps better suited for full sized vehicles.
 

[Chris(WA)]

Thanks!
 

[WFE2-70 NWIA]

Thanks for all the help and advise. These ramps that I bought on the sale were homemade. He had both a 4-wheeler and a skid loader and I wasn't sure what he used the ramps for. I wanted to use these ramps for changing oil in the cars, as the ramps I have now are too short and the front of the car drags before the front wheel goes up the ramp. From the advise you have given me I'll just look for or make some different ramps. Thanks again for the help.