Weights & Balance Spreadsheet PLUS "Brain Teaser"

Topic 7485 | Page 1

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Rick S.'s Comment
member avatar

So back when Brett did the "Weights and Balance" Section of the Trucking Truth High Road CDL Training Program, I wrote a "quick & dirty" spreadsheet to run the numbers. I took a little time recently - to polish it up so now it's:

Ricks "Handy/Dandy Weights & Balance Calculator" <-- download Excel Spreadsheet there at link.

Instructions for how to use the spreadsheet are on the sheet - Simply enter your numbers in the GREEN BOXES, and the answer appears in the RED Boxes. You cannot modify the RED BOXES - they are locked. I double/triple checked the formulas using the examples in the TT High Road test. If you find any errors or want to suggest any additional calculations, PM me. This will run on (free) Excel for iPhones & Androids too - so you can transfer it to your SmartPhone and use it on that too.

And now for the BRAIN TEASER

truck driver scale ticket

Here's a scale ticket, where the DRIVES AND STEERS are OVER. For this teaser

Truck has dual 100 gallon tanks - they are 1/4 full NOW (no, fuel burn is NOT going to solve your problem here).

In addition to the LOAD - we want to FILL THE TANKS FULL (add 3/4 to the 1/4) - because at 6.5 MPG, we aren't going to get very far, and don't want to keep stopping (every 400 miles), and adding 50 gallons (nor do we want to run the tanks empty, and keep sucking all the junk in the bottom of the tanks into our fuel filters).

Tractor Weight Distribution - 15% Drives / 85% Steers

5th Wheel Slide - 500 lbs per hole Trailer Slide - 4" - 250 lbs per hole.

Fuel: 8 lbs per gallon

Steers Legal: 12,000 lbs. Drives & Trailer Legal: 34,000 lbs.

After adding fuel to a FULL TANK OF FUEL - what would you do (sliders) to get the axles legal?

What would the FINAL WEIGHT BE for each axle?

(hint) Do the TRACTOR FIRST, don't forget the weight of the added fuel.

Good luck!

Rick

CDL:

Commercial Driver's License (CDL)

A CDL is required to drive any of the following vehicles:

  • Any combination of vehicles with a gross combined weight rating (GCWR) of 26,001 or more pounds, providing the gross vehicle weight rating (GVWR) of the vehicle being towed is in excess of 10,000 pounds.
  • Any single vehicle with a GVWR of 26,001 or more pounds, or any such vehicle towing another not in excess of 10,000 pounds.
  • Any vehicle, regardless of size, designed to transport 16 or more persons, including the driver.
  • Any vehicle required by federal regulations to be placarded while transporting hazardous materials.
Chiefmac's Comment
member avatar

Thanks Rick for the brain teaser and the spreadsheet. I started doing a spreadsheet the other night but was not as complete as yours. Below are my answers and I hope that we get some more questions like this one. It is really helping me see the real world applications of the stuff in all the books.

trucking brainteaser weight spreadsheetthank-you.gif

David's Comment
member avatar

So back when Brett did the "Weights and Balance" Section of the Trucking Truth High Road CDL Training Program, I wrote a "quick & dirty" spreadsheet to run the numbers. I took a little time recently - to polish it up so now it's:

Ricks "Handy/Dandy Weights & Balance Calculator" <-- download Excel Spreadsheet there at link.

Instructions for how to use the spreadsheet are on the sheet - Simply enter your numbers in the GREEN BOXES, and the answer appears in the RED Boxes. You cannot modify the RED BOXES - they are locked. I double/triple checked the formulas using the examples in the TT High Road test. If you find any errors or want to suggest any additional calculations, PM me. This will run on (free) Excel for iPhones & Androids too - so you can transfer it to your SmartPhone and use it on that too.

And now for the BRAIN TEASER

Scale-Tickets.jpg

Here's a scale ticket, where the DRIVES AND STEERS are OVER. For this teaser

Truck has dual 100 gallon tanks - they are 1/4 full NOW (no, fuel burn is NOT going to solve your problem here).

In addition to the LOAD - we want to FILL THE TANKS FULL (add 3/4 to the 1/4) - because at 6.5 MPG, we aren't going to get very far, and don't want to keep stopping (every 400 miles), and adding 50 gallons (nor do we want to run the tanks empty, and keep sucking all the junk in the bottom of the tanks into our fuel filters).

Tractor Weight Distribution - 15% Drives / 85% Steers

5th Wheel Slide - 500 lbs per hole Trailer Slide - 4" - 250 lbs per hole.

Fuel: 8 lbs per gallon

Steers Legal: 12,000 lbs. Drives & Trailer Legal: 34,000 lbs.

After adding fuel to a FULL TANK OF FUEL - what would you do (sliders) to get the axles legal?

What would the FINAL WEIGHT BE for each axle?

(hint) Do the TRACTOR FIRST, don't forget the weight of the added fuel.

Good luck!

Rick

To clarify, and depending on the temp, Diesel fuel weighs out around 7.15/lbs per gal. over estimating is good however more accurate result would be using 7.15 or 7.2 if you want round up. =)

now there is some missing info, as in where are your tanks located the most? front or rear of tractor.. Unless thats what you mean with weight distribution.. then I retract this.... what hole is the trailer currently in, and same with 5th wheel and is the trailer going into a length limit state such as CA or Illinois?

personally, I would start with trailer, get it as close to 34000, (can always move again as it's easier then the 5th) then slide 5th 2-3 holes back but every driver does it differently.

CDL:

Commercial Driver's License (CDL)

A CDL is required to drive any of the following vehicles:

  • Any combination of vehicles with a gross combined weight rating (GCWR) of 26,001 or more pounds, providing the gross vehicle weight rating (GVWR) of the vehicle being towed is in excess of 10,000 pounds.
  • Any single vehicle with a GVWR of 26,001 or more pounds, or any such vehicle towing another not in excess of 10,000 pounds.
  • Any vehicle, regardless of size, designed to transport 16 or more persons, including the driver.
  • Any vehicle required by federal regulations to be placarded while transporting hazardous materials.
Rick S.'s Comment
member avatar

double-quotes-start.png

To clarify, and depending on the temp, Diesel fuel weighs out around 7.15/lbs per gal. over estimating is good however more accurate result would be using 7.15 or 7.2 if you want round up. =)

now there is some missing info, as in where are your tanks located the most? front or rear of tractor.. Unless thats what you mean with weight distribution.. then I retract this.... what hole is the trailer currently in, and same with 5th wheel and is the trailer going into a length limit state such as CA or Illinois?

personally, I would start with trailer, get it as close to 34000, (can always move again as it's easier then the 5th) then slide 5th 2-3 holes back but every driver does it differently.

double-quotes-end.png

The spreadsheet and brain teaser was meant to pretty much go along with what the TT High Road Weights & Balance teaches - which is why I used numbers to coincide with what's being taught there.

Hence the gallon = 8 lbs. Though diesel at "room temp", is closer to 7.49 lbs.

1 US gallon = 3.7854118 liter

Density of diesel= 900 kg/m³

1 liter = 0.001 cubic meters (volume) and Weight= volume×density weight of 1 gallon of diesel is

= 3.78*900*.001 = 3.402 kg or 7.49 pounds approximately

As far as "tank location" - this is where the 85%/15% comes in - as the TTHRT teaches how to figure out ratio of fuel weight - by weighing before and after fueling, and using the increase in gross/drive/steer weights added by fuel, in an equation to determine where the ratio of where the weight will go on the tractor.

Part of the "brain teaser" here, was to throw in the additional fuel, ON TOP OF the already overweight condition of the tractor - simply because it required the extra brain work to calculate the weight of the additional fuel BEFORE you started calculating the slides required to balance.

I suspect, due to the "already overweight condition" of the steers - the truck on this ticket probably already had a full load of fuel onboard. I threw in the addition of fuel as the added "curve ball" to the project.

Using the calculations (or the spreadsheet) you could plug in the weights and pretty much get dead on, what has to slide where, to balance and get legal. Keeping in mind that different tractors have a different wight range on the 5th wheel holes (or I should say, different 5th wheel manufacturers), and likewise different trailers and going to also (slightly) different weights shifted per hole.

Being that the steers were over to begin with - the 5th wheel is going to have to be moved - regardless of whether you make the drives legal first or not. And you're correct - which you slide first is a matter of preference - but I'd get my STEERS LEGAL FIRST, because shifting the drives/tandems weight is not going to affect the steers much anyway - and they're already overweight - if anything the added weight on the drives, may actually be "lightening" the drives through the effect of "leverage".

As far as "tandem to kingpin length" or where the tandems were to begin with - Daniel B. brought that up when I talked to him this morning. My thoughts too - were: are there actually that many holes forward from a 40' Bridge Formula configuration (assuming that's where the tandems STARTED FROM) - to actually slide the requisite number of holes in the first place. But since this example requires a SUBSTANTIAL forward slide of the tandems, I would think it would be "bridge formula legal" when you were finished balancing anyways.

Looking at the weigh ticket - it's pretty obvious that the load was too far forward to begin with (being that it was 4,220 lbs "front heavy" to begin with) - or it may have been a reefer (which would add 1,800 lbs +/- to the front of the trailer) that was responsible for some of the "front heaviness".

The point of the exercise, was to use the formulas and information in the "Weights & Balance" section of the High Road - to solve how to get the axles legal.

Rick

Tandems:

Tandem Axles

A set of axles spaced close together, legally defined as more than 40 and less than 96 inches apart by the USDOT. Drivers tend to refer to the tandem axles on their trailer as just "tandems". You might hear a driver say, "I'm 400 pounds overweight on my tandems", referring to his trailer tandems, not his tractor tandems. Tractor tandems are generally just referred to as "drives" which is short for "drive axles".

Tandem:

Tandem Axles

A set of axles spaced close together, legally defined as more than 40 and less than 96 inches apart by the USDOT. Drivers tend to refer to the tandem axles on their trailer as just "tandems". You might hear a driver say, "I'm 400 pounds overweight on my tandems", referring to his trailer tandems, not his tractor tandems. Tractor tandems are generally just referred to as "drives" which is short for "drive axles".

Reefer:

A refrigerated trailer.

Rick S.'s Comment
member avatar

By the way - ChiefMac was on the money. I slide the tandems only far enough to get the drives legal - but the load ended up 1,241 lbs "out of balance".

Starting Weights:

Steers - 12,400 (OVER by 400 lbs) Drives - 34,500 (OVER by 500 lbs) Tandems - 30,380 (UNDER by 3,620)

We want to fill the tanks, which means ADDING 150 gallons of fuel.

At 8 lbs per gallon - we’re adding 1,200 lbs of additional weight to the tractor.

With 85% Steers and 15% this means the NEW WEIGHTS AFTER FUELING are:

Steers: 13,420 (1,420 lbs over) Drives: 34,680 (680 lbs over)

So first we, slide the 5th wheel BACK (shifting weight from the steers to the drives) 3 holes. This moves 1,500 lbs OFF the steers.

Weight after sliding 5th wheel:

Steers: 11,920 (Legal) Drives: 36,180 (2,180 lbs OVER)

Now we slide the trailer tandems FORWARD 9 holes (shifting weight from the drives to the trailer tandems). This moves 2,250 lbs OFF the drives and onto the trailer tandems.

Final Weights:

Steers: 11,920 lbs (LEGAL) Drives: 33,930 lbs (LEGAL) Tandems: 32,690 (LEGAL)

You could probably move the trailers forward and additional hole (10 holes - just to be safe) and you would have:

Drives: 33,680 Tandems: 32,880

Gives a little more of a “comfort level” - not being as “close to max” on the drives.

Conversely, at 2,720 under gross - you could also forgo the full tank and only go to 1/2 a tank (to save 600 lbs, most of which is going to the steers).

It would then look like this:

With only 600 lbs added fuel: Steers: 12,910 Drives: 34,590

Slide 5th wheel back 2 holes:

Steers: 11,910 Drives: 35,590

Slide the tandems forward 7 holes and you get:

Drives: 33,840 Tandems: 32,130

The point of the exercise (again), was to use what is being taught in the "Weights and Balance" section of the sites training - to "problem solve". It also gave me the chance/excuse to post my calculations spreadsheet. Wish I knew how to write apps - I'd make one for iPhone/Android - wait - I want to get OUT OF THE IT BUSINESS (LOL).

The other point being - getting used to using what you learn here on the site - and applying it in the field, can turn a "head scratcher" into a quick solution. Using the calculator let's you do "what if's" to determine the added weights of fueling - BEFORE adding fuel, or sliding in a "hit or miss" fashion.

Rick

Tandems:

Tandem Axles

A set of axles spaced close together, legally defined as more than 40 and less than 96 inches apart by the USDOT. Drivers tend to refer to the tandem axles on their trailer as just "tandems". You might hear a driver say, "I'm 400 pounds overweight on my tandems", referring to his trailer tandems, not his tractor tandems. Tractor tandems are generally just referred to as "drives" which is short for "drive axles".

Tandem:

Tandem Axles

A set of axles spaced close together, legally defined as more than 40 and less than 96 inches apart by the USDOT. Drivers tend to refer to the tandem axles on their trailer as just "tandems". You might hear a driver say, "I'm 400 pounds overweight on my tandems", referring to his trailer tandems, not his tractor tandems. Tractor tandems are generally just referred to as "drives" which is short for "drive axles".

Fm:

Dispatcher, Fleet Manager, Driver Manager

The primary person a driver communicates with at his/her company. A dispatcher can play many roles, depending on the company's structure. Dispatchers may assign freight, file requests for home time, relay messages between the driver and management, inform customer service of any delays, change appointment times, and report information to the load planners.
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