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Old 07-09-2015, 09:31 PM   #1
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Using Scales to Fine Tune Your Setup

There's information all over the forum on the value of getting your setup right - perhaps the #1 safety factor in towing - and the value of scales in doing so, but a quick search didn't come up with a thread dedicated to the topic. This is such an important topic that I think it would be really useful to compile some of the spread-out information by aggregating it into a single thread.

I'll start things off by posting a link to a great resource for finding scales:

Coops Are Open

Cheers,
John

Note to Moderators: Is it OK to compile other posts on this topic by copying and pasting them here, or is it necessary to only provide links?
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Old 07-10-2015, 05:37 AM   #2
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( forum member Ron G posted this "how-to" in another forum. Hopefully Ron does not mind me doing a cut/paste here )
==================

If you want to use the scales data to determine tongue weight, and if you want to get the maximum information about your TV/TT combination and how well your weight distrtibution system is working, you need data from three weighings. Second and third weighings usually are done at a lower cost.

And, you need to find a scales with at least three separate weighing platforms so you can separately measure all three axle loads at the same time. Most, perhaps all, CAT scales have this feature.

If you need any help in interpreting the scales results, just post the numbers. There are several ORF members who can help with the calculations.

First, the TV and TT should be loaded approximately as they would be for camping.

Second, the weight distribution system should be adjusted as it normally would be for towing.

Then, I would do the following:

Weighing #1 -- TT attached and Weight Distribution Activated
Let Front Axle Load be "FA1"
Let Rear Axle Load be "RA1"
Let TT Axles Load be "TT1"

Then, remaining in same position on scales, take
Weighing #2 -- TT attached and Weight Distribution Not Activated (WD bars unloaded, but hanging in place) -- ask the operator for a "re-weigh":
Let Front Axle Load be "FA2"
Let Rear Axle Load be "RA2"
Let TT Axles Load be "TT2"

Then, drive off scales and drop TT. Return to scales and take
Weighing #3 -- TV only -- TT Not Attached -- ask operator for another re-weigh:
Let Front Axle Load be "FA3"
Let Rear Axle Load be "RA3"

From the above values, you can calculate:

TV weight = FA3 + RA3

Gross Combined Weight = (FA1 + RA1 + TT1)
{should also be equal to (FA2 + RA2 + TT2) if scale weights are correct}

TT Weight = Gross Combined Weight - TV Weight

Tongue Weight = (FA2 + RA2) - (FA3 + RA3)

Load Transferred to TT Axles
when WD System is Activated = TT1 - TT2

This procedure should get you on and off the scales fairly quickly and still provide all the data you need.

Ron
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Old 07-10-2015, 08:15 AM   #3
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And here's a spreadsheet that you can fill in using Ron's formulas.

Cat Calc Sierra 2500 5-3-14.xls
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Old 07-10-2015, 08:15 AM   #4
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Example ^


TV alone loaded...



NO WD & WD....


The actual CAT tickets are my 'spread sheet'.

Bob
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Old 07-10-2015, 08:26 AM   #5
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Here's a link to where to find and how to use CAT scales: CAT Scale

Cheers,
John
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Old 07-10-2015, 09:08 AM   #6
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I found that the one of the local moving and storage companies had a set of scales available to the public. I weighed on them first, then at a CAT scale. The two weighings correlated well. So if there isn't a CAT scale near you, try your local M&S companies.

Their pads are slightly different so you may have to adopt a different set of calculations. For each of the three conditions - Truck only (W1 and W2 below), W/D on, and W/D off I did the following measurements:

Weight 1 - Steer axle
Weight 2 - Both Truck Axles
Weight 3 - Trailer

So weight one suffices for the steer axle, Weight 2-Weight 1 = Drive axle, Weight 3 is the trailer.

Then you can use the data in the spreadsheet provided above

Al
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Old 07-10-2015, 09:29 AM   #7
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Great thread here by Ron Gratz on weight distribution: http://www.airforums.com/forums/f464...ml#post1524036

Cheers,
John
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Old 07-10-2015, 12:44 PM   #8
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I am new to towing an AS. I have towed various types of trailers since I was a teenager (long time ago. I have read all the hitch, TV, etc. articles with great interest. This thread and the Ron Gratz link have been the most helpful to date. I believe I can use this information to set up correctly and have "peace of mind" when towing. THANKS to ALL of you who contribute here.
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