Building ramp need help

[sti1471]

I am planning to build some trailer ramps. I drive a semi truck, and am looking to hauling boats and vehicles in the enclosed trailer. The ramps will be 14' in length, but each ramp will be two 7' ramps connected together for a total of 14' and supported in the center by Jack's. The max weight that I would lead on them would be something like an f350 so around 7k lbs.

however I am not sure how thick of metal I should use. I was thinking of using square tube of 1.5" .100 or .120 wall thickness. And then have 1" .80 wall as cross traction bars.

would this be strong enough to support 7k lbs. Attached is a picture of what I am trying to build.

 

[M2HB]

I am planning to build some trailer ramps. I drive a semi truck, and am looking to hauling boats and vehicles in the enclosed trailer. The ramps will be 14' in length, but each ramp will be two 7' ramps connected together for a total of 14' and supported in the center by Jack's. The max weight that I would lead on them would be something like an f350 so around 7k lbs.

however I am not sure how thick of metal I should use. I was thinking of using square tube of 1.5" .100 or .120 wall thickness. And then have 1" .80 wall as cross traction bars.

would this be strong enough to support 7k lbs. Attached is a picture of what I am trying to build.

No, 1-1/2' tubing will not be anywhere near strong enough.

I would build the frame of the ramps out of 4" standard channel. Even that is pushing it with only one support in the middle at 7'.

2"x2"x3/16" angle iron would make great cross members.

 

[Scott Danforth]

It would be cheaper to buy it vs making it. The 1-1/2" tubing wont be strong enough as it sits. The ramps shown have 4 stringers in each ramp, about 3" tall (guessing from pic).

You also have the traction issue to contend with.

From a safety standpoint, you will want to design for a dynamic load, which could be 5 or 6 times the static load.

Then there is the liability side of it. Build the ramps and you own it if there is a failure. Buy the ramps, and the company owns it if there is a failure.

 

[sti1471]

What about 2x2 3/16 angle iron as the main beams? I see the commercial ramps have 3 stringers, but those ramps are made of aluminum which I dont think had the same strength as steel.

The cost of those ramps if I buy them are 2,700.00. Each 7' ramp will only have 1/4 vehicle weight on it at any time. Maybe I should have a ground support every 3 feet for each ramp. One at 3 feet, 6 ft, and 9 feet?

 

[Scott Danforth]

depending on the grade of aluminum, it could be 3-4 x stronger than standard A36 structural steel. most likely its a 6000 series, so it would be close to the same. Aluminum is also 1/3 the weight of steel.

Aluminum would be preferred over steel just for the weight of the final product. if you build it in steel, you may not be able to move it without a fork lift.

$2700 is cheap. consider the cost if a ramp you build fails.

I personally would build it out of aluminum and carbon fiber to increase stiffness and reduce weight, however that would put the cost well over $5k in materials alone

 

[M2HB]

Sti, 1-1/2” angle iron is nowhere near strong enough for the main members. I’ve builtbequipment trailers on and off for over 40 years. With your weight load, I think 4” channel is right for a 7’ long ramp. As for supporting it anywhere besides the middle. Your ground is usually not perfectly level so anywhere besides the middle, where it would fold anyway, probably won’t work well. A 7’ long ramp is not unusual on an equipment trailer but they usually have a hinge on the trailer and a “helper” spring because they are heavy.
aluminum would be nice. I can’t help you there because I haven’t built any aluminum trailers.

 

[Scott Danforth]

looking to hauling boats and vehicles in the enclosed trailer. .

another thing to consider. most boats are wider than the door opening on enclosed trailers unless your talking hauling old utility boats and small runabouts

all my boats over 17' are at 102" which is the overall width of your enclosed trailer. Many in the 24'+ range are much wider

most high-cube trailers have a 93" wide opening and a 99" interior width as max.

I would be looking for a car-hauling trailer for hauling vehicles and a flat-bed for boats.

 

[alldodge]

Your wanting to do this for versatility.

Building ramps leaves you open to law suits if something goes wrong.
The ramps are going to be very heavy, so is their a plan to move and store for off load later?
Will also need something to load and unload boat. This can be a local truck, but having the owner do it but this opens up again a liability issue if something goes wrong

Think what you really need is a roll back with a box installed on the bed

 

[ahicks]

Weight of those ramps would concern me as well. Alum. ramps on the scale you're considering are going to be tough to handle, even in 4 sections. Steel would not be a part of any plan I'd be interested in.

 

[sti1471]

You all make good points. Most of the boats I would be hauling would be boats that are already on trailers, and they are smaller boats, jet skies type loads.

ok, so let's say I get rid of the vehicle idea, and say that i decide to just accept atvs, utvs, motorcycles, and small boats. Loads under 2000 lbs until I could get a better trailer. Would 1.5" steel work for loads under 2k lbs?

 

[briangcc]

You seem fixated on trailer boats. How is the trailer boat getting into your trailer? Are you towing it up your ramp thereby trapping the tow vehicle in your trailer for the ride? Or are you backing it up the ramp where hopefully the coupler is in top notch form otherwise when it pops you now have an unsecured load headed for the back of the pushing vehicle? And how are you getting it out of the trailer on the other end?

Limiting the trailer boat to 2000 lbs means just about anyone can tow that - small SUV's, minivans, some cars, small/mid-sized pickups, etc. Not something I'd be shipping unless its a very long haul...even then, I'm going to go get it myself and save on the shipping fees.

Personally, if I'm paying for transport of my boat, the hauler is showing up with the correct equipment to handle the load or he/she is being sent on their way.

 

[sti1471]

I would use a winch to bring it into the truck, and reverse the winch to lower it down the ramps. That just it, I do long haul runs, and many times I have enough room for a boat, or motorcycle, or I am deadheading back 500 miles and there is something I can deliver on my way back but without ramps I keep passing on atvs, motorcycles, and utvs. Since I am heading that way anyways, my quote is usually less than it would cost them in gas to get it themselves.

I do this because I like to have weight in the trailer for windy areas.

 

[ahicks]

I get what you are trying to do, but it seems like a lift gate would handle a lot of that?

 

[dingbat]

depending on the grade of aluminum, it could be 3-4 x stronger than standard A36 structural steel. most likely its a 6000 series, so it would be close to the same. .

strength isn’t the issue here...its deflection

Unlike strength, which can vary from grade to grade or even coil to coil, Young’s Modulus is constant for a given metal and is independent of heat treatment, processing, or cold work. Young’s Modulus for steel (29 million PSI) is three times that of aluminum (10 million PSI). This means that for a fixed geometry, a part made out of steel will be three times as stiff as if it were made out of aluminum. In other words, an aluminum part under load will deflect three times as much as a similarly loaded steel part.

 

[Scott Danforth]

that is correct. add to that the cross-sectional shape of the structure (moment of inertia) and over-all height of the shape, and that all comes into play. only with a given fixed cross-section can we compare materials and look at deflection based solely on Young's Modulus. any good engineer would know that.

the question raised wasn't deflection, or fatigue cycles, etc. it was purely "will blah blah blah be strong enough" so I limited the answers to strength. as i stated in post #5, if I was designing it, i would go with a composite matrix of aluminum (most likely 7075 aluminum ) and a layup of carbon fiber. I would also install a few rosettes of strain gauges and turn it into a scale to ensure i didnt over-load it. carbon fiber is a wonderful thing, however unlike steel and aluminum which telegraph an impending failure long before the material fails (bends, crazing, etc), carbon fiber simply explodes and fails with a glorious earth-shattering kaboom.

 

[dingbat]

the question raised wasn't deflection, or fatigue cycles, etc. it was purely "will blah blah blah be strong enough" so I limited the answers to strength. as i stated in post #5, if I was designing it, i would go with a composite matrix of aluminum (most likely 7075 aluminum ) and a layup of carbon fiber. I would also install a few rosettes of strain gauges and turn it into a scale to ensure i didnt over-load it. carbon fiber is a wonderful thing, however unlike steel and aluminum which telegraph an impending failure long before the material fails (bends, crazing, etc), carbon fiber simply explodes and fails with a glorious earth-shattering kaboom.

Ill keep this in mind the next time I’m designing car ramps for use on Mars to NASA specifications and budget constraints..lol

 

[Bondo]

You all make good points. Most of the boats I would be hauling would be boats that are already on trailers, and they are smaller boats, jet skies type loads.

ok, so let's say I get rid of the vehicle idea, and say that i decide to just accept atvs, utvs, motorcycles, and small boats. Loads under 2000 lbs until I could get a better trailer. Would 1.5" steel work for loads under 2k lbs?

Ayuh,...... Ya need to find a class 8 truck Scrapper,.....

Car carriers have all sortsa aluminum, 'n steel ramps of various widths, 'n lengths,.....

I once hauled a compact tractor on a stripped down boat wagon,.....
2 ramps for a bed, 'n 2 ramps as ramps,.....