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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.

Hammerhead

So how do we use this information to adjust a load we loaded wrong?
Let's say we loaded a 46500lbs load with the above unit, but we missed our Target and the shipper will only move the load once, and we have very little room to play with.
Let's say we ended up at
11900
32500
35100
So we need to move a minimum of 1100lbs forward, but not more than 1500.
To balance, our Target should be 1300 lbs.

Our load weighs 46500 and we need to move 1300 of that so:
1300/46500=0.02796 or 2.8%
Our trailer w/b is 41' or 492"
So we need to move the load 2.8% of the wheelbase
492*0.028=13.77"
So we're going to move the load 13-3/4" ahead to reach our goal of 33800 each tandem group.

Magard

Math works. Math is how I load my cattle trailer also. Percentages of load designated per compartment. There are different configurations in the trailer so percentages change with configuration. We always load a little over gross to be perfect when we hit the scales because the load shrinks as time goes by. So no room for error 12 34 34 = 80. I do find it funny how many people just guess and hope for the best.

Hammerhead

(08-08-2019 )Magard Wrote: Math works...

Every time...unless I do it wrong:waaaht:

Chamberpains

I'll be making a copy of that for quick access in the truck. I've always hated using the center lights as the center point of a trailer. Sliding axles and tandems move the center point. So that light is useless.

Here's another question. How do you figure the center of gravity of a drive on piece of machinery or non crane loaded piece? That has always been a huge guessing game to me. I use measuring the center of lifting hooks if they are available. But do you have any tricks on non conventional pieces? Any crane operators that may have a trick or 2?

Hammerhead

(08-08-2019 )Chamberpains Wrote: I'll be making a copy of that for quick access in the truck. I've always hated using the center lights as the center point of a trailer. Sliding axles and tandems move the center point. So that light is useless.

Here's another question. How do you figure the center of gravity of a drive on piece of machinery or non crane loaded piece? That has always been a huge guessing game to me. I use measuring the center of lifting hooks if they are available. But do you have any tricks on non conventional pieces? Any crane operators that may have a trick or 2?

For RORO (Roll On-Roll Off) equipmenot, if it's tracked and you're loading it on an RGN, watch where it breaks over back to level, that's it's C/G. If you're self loading, stop as soon as it breaks and get out and Mark it with a sharpie. I do this ALL the time on unknown stuff. If it's something with a boom (excavator), try and have the boom/stick in the approximate transport position for more accurate results.

For wheeled equipment, some mfgrs list the tare axle weights of machines on their websites. From there, it's just the same math backwards. The heavy axle is how much % of the machine and that percentage measurement of the w/b will give you it's C/G.
If it's a machine you will haul regularly, knowing you're tare axle weights, your loaded axle weights and using the formula you can actually find it that way, it's a little longer, but if you do a lot of them, it may be worth knowing.

For crane stuff, if it's a single crane that's easy. The C/G ALWAYS runs through the cable line of the crane. Doesn't matter if they're using different length of slings or a spreader bar, the C/G by the Laws of Physics MUST be in line with the cranes cable line.
If it's dual crane lifts, then we're back to math. All cranes "should" have and on board lift scale. They're not accurate, but they're good enough to calculate C/G, because we're looking for percentage, not exact weights. Get each cranes load weight, calculate percentages, and then instead of w/b, measure % of pick points. Pick points are the exact same concept of w/b, except they're hanging instead of sitting.

I have a Book of Knowledge , and I keeps notes of everything. It's a big binder with almost every load I've ever hauled. I have configuration drawing blanks, and then I draw on them and note everything including measurements. It's a binder with about 20 category dividers, so I can find something right quick. I can repeat a load I haven't seen or hauled in 10yrs because I have the info. When I sell my trailer, the guy that buys it is gonna look like a rockstar if he follows the Book, cause the learnig curve will be flattened for him.