Truck Body Cog Calculation

Depends on your design software.

The new CAD programs SolidWorks, etc. can do that.

Me, I'd take a WAG that the COG will be somewhere near the lower middle of the (full) water tank, assuming that the tank is holding a slurry.

If you start with 12,000#, and the loaded weight is 40,000#, that is.

Thanks, Lyn

x' = ∑xw/∑w
y' = ∑yw/∑w
z' = ∑zw/∑w

Tornado:

Thanks...

What unbits are x,y,z, and w ?

They are the same.

x, y, z are distances from whatever origin point is chosen; w is weight.

A piece of 2in cylindrical bar, some paint, a piece of flat floor and a crane is all that is needed to measure it and mark it.

I am assuming that it's supported by 4 "feet". Put a scale under each foot. If W1 is the sum of the weight at one end and W2 is the weight at the other end, then x1 * W1 = x2 * W2, where x1 is the distance from one and x2 is the distance from the other end. x1 + x2 = total length.

Find the CG distance crosswise by adding the weights on each side, W3 and W4. Find distances x3 and x4 as before.

To find the vertical distance, you will have to lift it with a crane from one side until it is balanced on two feet and measure the angle the plane of the four feet make with the horizontal. The vertical distance from the feet to the CG will be the horizontal distance divided by the tangent of this angle.

Seems like you shouldn't have to use a crane to tilt it to a balancing point. Just measure the weights under each foot with the whole thing at some measurable non-negligible angle (less than balancing/tipping) should allow calculation.

You must also be cognizant that COG will change position, and level as truck moves to more and more incline. Do you incorporate an inclinometer on the truck with a warning patch in orange for approaching critical tip angle, and red for you already turned over?

Break the truck, all equipment, and cargo up into pixels of known density, and calculate the summation balance (i.e. used prepackaged software for this). Very important safety information about your product will be found this way.

Unless these trucks have wheeled outriggers, and I have never seen such, it is ill-advised to be on a high slope angle even if deemed safe, because even one rise on the high side, or dip on the low side will result in a tip, most likely.

You are importantly establishing safe modes of operation for the product, and the safest is level field. Since that is not available, find the most suitable compromise of operability where safety is never compromised, otherwise lawyers will be happy to take care of the problem(s) for you.

The center of gravity will change when the trailer is loaded....it's important to be able to calculate the weight distribution to keep proper amount of tongue weight for stability purposes...

http://www.hydroseeding.org/forum/index.php?PHPSESSID=fcs61afb9don171qlbaetk9005&topic=6093.0;nowap

http://www.finncorp.com/wp-content/uploads/2015/12/HSTruckMounting.pdf

http://www.longacreracing.com/technical-articles.aspx?item=42586

http://www.wikihow.com/Calculate-Center-of-Gravity

The cog will also vary with "sloshing" about. (remember the Mary Rose.)

What may be stable on an incline may well roll over when e.g. turning a corner.
The liquid seriously affecting the stability. Not so funny this stability, ask any farmer.
When this size weight and volume are moving, professional advice is required with,
I would recommend, a huge margin of safety. (been there myself!)

jt.

Life's like that, one minute you're up, next minute you've rolled over! Just like that!