Adjustable height suspension for tandem 10k trailer

[wrightpt]

I have linked a document (Trailer_Design_PDF.pdf) going over the design and function of a suspension the allows the trailer frame to move up and down with the help of airbags. Technically known as: "MODULAR DYNAMICALLY ADJUSTABLE SUSPENSION SYSTEM FOR TRAILER." Essentially a trailer that has the ability to change frame height.



However, "The following is a simplified summary of the invention in order to provide a basic understanding of some of the aspects of the invention. This summary is not intended to identify key or critical elements of the invention or to define the scope of the invention."
I have 2 5200 lbs drop axles, with a frame that is approx 17 feet tall and 6.5 feet wide. The trailer needs to be widened. The axles are as long as legally possible around 120-122 inches or so.



Below are a few pictures showing the basic design. Of course, i welcome criticism, comments, and recommendations on this design. Will it be strong enough to carry a 4500 pound load of wooden pallets? a 6k pound forklift? etc. What are the weak points? what can be changed to get around such frailty?


What really stands out to me are the parts with the following numbers.


pan-hard bar (150) = Panhard bar is a device that can be used to locate a solid rear axle under a vehicle. ... During cornering or sideways movements of the vehicle, the bar keeps the axle located laterally under the body. In this case, one or more pan-hard bars are connected on one side of the said trailer frame and traverse the width of the said trailer frame to connect to a Trailing Arms or (squat bar as the author calls it) (165) mounted on an opposite side of said trailer frame, wherein said pan-hard bar serves to locate and center the drop axle.


I think i can buy most parts off the shelf. I just wonder how improvements to this design can be made.

The deck of the trailer (110) can also be raised above the centerline of the trailer's wheels 115. In an embodiment, the trailer wheels 115 are typically 12" to 25" diameter towing wheels depending on the trailer frame requirements. As explained above, in an exemplary embodiment, smaller diameter wheels are used to facilitate lowering the deck of the trailer 110 closer to the ground.


Source: US8840119B2 - Modular dynamically adjustable suspension system for trailers
- Google Patents

 

[tomjelly]

Not sure what you mean by 122" wide axles as to be road legal you need to be under 102"

 

[Superbowl]

Your post tells us nothing about the frame members. Are they 18 gauge aluminum channel or 1/4" steel channel? Are they 2" deep or 6" deep?Since you provide so little useful information I don't think you have thought this through enough to ask the group for help.

 

[David_M]

What is drawn would be bound up. It could only have suspension travel by having a component flex in a way that would cause cracking, in my opinion.

 

[Milland]

If we're to take the drawings at all literally, there's a number of issues:

1) Ladder frame with very little diagonal bracing (just at the hitch end), which means it's subject to racking (parallelogram movement) under stress (such as one wheel hitting a bump or pothole in the road). This will induce a steering force into the beam axle, giving unpredictable handling of the trailer.

2) Ladder frames by their nature have very low torsional stiffness, and under loading or driving forces could again induce axle steer.

3) Along these lines, if you have a single-side failure of the airbag system, so one side dips while the other maintains original height? Almost certain erratic steering will result.

See the theme? Suspension geometry MATTERS!

4) Speaking of, the laydown of the shock absorbers is such that they're kinematically inefficient.

5) Mechanical assembly, strength of joints, proper load capacity - as already stated, not enough information to make judgements. Overbuilding is good, unless you're making an aircraft.

[And it's good there too - make your aircraft too heavy to fly until you understand the engineering and dynamics involved]

 

[RC Mech]

Better geometry would be twin I-beam suspension like Ford was making in 1965. Same propensity to scrub tires as the above design. Even better would be to ditch the beam axle entirely in favour of independent control arms for each side.

 

[john.k]

ladder frame with flexing is standard practice in trailers.....I suggest the application of airbags to trailer suspension is well developed,and all thats required is to copy a successful system.......The designs offered indicate zero familiarity with the demands of transport vehicles and components.

 

[DDoug]

Apparently the OP just likes to post...and NOT answer any questions:
Adjustable height suspension for tandem 10k trailer

 

[plastikdreams]

Probably better off with a watts linkage...or a triangulated 3 link...or 4 link. When I built my bagged s10 in the early 2000s I used a tri 3 link and it worked fine. In both behind the axle sleeved bags and over the axle 2 bellow bags.

 

[BT Fabrication]

Trailers are designed to be cheap and simple to build and maintain. Its not a race car. it just needs to hold the weight, no need to reinvent the wheel.