Threaded Mode | Linear Mode

Hammerhead

There is a mathematical formula that is used to Target Load.
Target Loading is loading a single piece on a known configuration, with little to ZERO room for error.
I use this formula regularly for my multi-axle, and load with less than 1000 of goal room to spare on a 5 group configuration, so yeah I'm confident in it.

I'm going to break it down for an atypical 5 axle deck.
Now I'm going from way old memory on specifics, as I haven't pulled a 5 axle in nearly 20 years.

Let's use the following configuration, just change the measurements for your unit, and recalculate for your personal setup.
Truck: 244" w/b
Trailer: 48' deck with a 24" kingpin and a 54" closed spread that is set at 41' bridge (this is actually the wrong term). That's 41' from the kingpin to the CENTER of the trailer axles group.
Unit weighs 33,000lbs empty.
We're going to load a 58,000lbs single piece on the docks using a ship crane for a direct discharge. A 5 axle can load a single piece non-reducible load and permit to a Max of 92,000 lbs...we're gonna be 91,000! And with a ship crane, we can't pick it back up or move it, so we HAVE to get it right THE FIRST TIME.
So how do we do that?

Tare Weights are:
11600 Steer
12300 Drives
9100 Trailer
33000 Tare

Target Weights:
12000 S
39500 D
39500 T
91000 G

So our Target Distribution Capacity looks like this:
Steer: 12000-11600=400lbs
Drives: 39500-12300=27200lbs
Trailer: 39500-9100=30400

This is a simple config, so this is the simple formula
Load is 58000 and 30400 of that needs to land on the trailer, so as a percentage that means
30400/58000=0.524 or 52.4% of the payload must load the trailer axles.
Our example trailer has a 41' wheelbase. That's the exact measument from trailer kingpin to center of trailer axles. 41' is 492".
If 52.4% of the load needs to sit on the trailer, that means we need to put the center of gravity (C/G) of load 52.4% of the way into the w/b.
492"*0.524=257.88" 257.88 is 21' 5-7/8" so 21'6"
So measure 21'6" back from the KINGPIN or 23'6" from the front of the trailer (add the kingpin setting to the calculation if this is easier to measure from, and for most it is), and Mark the trailer.
Load the C/G on your Mark, and you'll be within 1% every time. If the C/G and weights are really accurate, you'll be within 100lbs.

Now we get into the front end, and we've put the remaining 27600 on the front, but our Target for the drives is only 27200.
27200/27600=0.9855 or 98.55%
Our truck w/b is 244", so we need to make sure our 5th wheel is 1.45% of the w/b ahead of the center of our drive axles to get the steers up to 12000 and our drives at 39500.
244*0.0145=3.53". Holland sliders are 1.5"/notch, so that means our 5th wheel must be 2 notches ahead of when it's centered. Since we have 1.5" notches and we needed 3.5", we'll actually end up at 11900 & 39600. So permit for 12, 40, 40, & I assure you you will be good.

So the simplistic of the formula is to take the trailer:
%PL is percentage of Payload Weight
TW is Target Weight
tw is tare weight
Formula is:
%PL=TW / tw
Measurement is:
%WB is percentage of wheelbase for C/G Target
WB is wheelbase measurement from the kingpin to center of axle group(converting to inches is more accurate)
%WB= WB / %PL

This does break down into a single formula, but it's a cneterd answer with a calculation over and under a division line, and I don't know how to get staright text to correctly show it.