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Topic ClosedLoading and balancing the trailer

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jato View Drop Down
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Direct Link To This Post Topic: Loading and balancing the trailer
    Posted: 17 Oct 2019 at 8:19pm
Wow, this is very interesting and you are taking it to a level that I am going to need more time to digest.  In the meantime I have a tee time for golf at 10 am, while my wife is waiting to go camping and then we will camp this Friday thru Sunday morning in Kingsley (MI).  Come home for a day and then leave again Monday morning for our last r-pod gathering with other podders near Roscommon at S. Higgens Lake State Park for a few days.  NO SNOW FORECAST ! so that is a good thing.  Problem is that for the 30 days we were gone in September in CO and UT we had bountiful sunshine EVERY day, man did we get spoiled!  Then back to gloomy northern Michigan.  We are about ready to go back west again, as you can imagine if you live in this neck of the woods. 

Back to the topic at hand,  Keep the posts rolling, I am learning a lot here, thank you all for all your expertise, hopefully this brain will be able to retain more than a trace of what has been shared thus far.
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offgrid View Drop Down
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Direct Link To This Post Posted: 17 Oct 2019 at 3:33pm
I think your 107 lbs and 253 lbs are correct if I understand your spreadsheet right. But you need to also consider the effect of the 253 lbs on the axle (and on the frame aft of the axle). I think if you add the 253 lbs 66 inches behind the axle you are increasing your axle load by 360 lbs (253 lbs plus the reduction in hitch load of 107 lbs). That's a LOT of extra weight/stress on the axle/stress on the frame to carry around. 

What is your Taco's hitch weight limit? Do you really need to keep the hitch weight down to 420 lbs?  

I don't have a handle on the side to side weight distribution on the axle. I do agree that the slide side is almost certainly heavier, numerous ppl have noticed that that side rides lower on their pods, and its my impression that there have been more axle failures on that side. The thing that is needed is for someone to actually measure their side to side weight balance. That's not so easy. It could be done with individual wheel scales or (maybe) with a Sherline with a board on top using legos to get each trailer wheel on there one at a time. 
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Direct Link To This Post Posted: 17 Oct 2019 at 2:36pm
Re-loading and weighing is taking time.. Thankfully it's raining and I can do this.

I've now past the axle and working aft. In the 182g I have a upper bunk which I remove and add a rear corner cabinet. 

This has brought on a interesting situation and as I think of it it applies to some of the fore weight as well. That is factoring weight per side on the axle. 
Being the slide side is probably heavy from just that, then add frig goodies and my pantry (your Micro) this seems to be fairly important. Especially since my issue was the frame on slide side.

Why do I have this feeling OG has a formula for just that.. I do not mean to put you on the spot, yet you do really understand these things. So I guess I do.. and it is so appreciated. 

So far the numbers are coming out heavier than I weighed in at, yet not quite done and seem to be on track. 

Goal for me is to get to my factored hitch weight 400#'s (or up to 420#'s). With all said and done right now, I'm looking at 281#'s of gear in the garage (or storage under). Which I highly doubt I now carry. I may just throw the spare back in the trailer and open up some cargo area in the Tacoma. 

Onward I go!

  


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Direct Link To This Post Posted: 17 Oct 2019 at 11:10am
Originally posted by offgrid

If I understand the question, I think that is incorrect.  Remember that in a statics problem both the weights and the moments have to independently net out to zero. 

So say if you add 100 lbs 4 feet behind the axle and the axle to hitch distance is 13 ft then you have reduced the hitch weight by 100*4/13=31 lbs. So to net out the new trailer total weight the axle weight has to go up by 100+31=131 lbs. 

If instead you add the 100 lbs 4 ft in front of the axle then the hitch weight is increased by the 31 lbs so the axle weight only goes up 100-31=69 lbs. 

Make sense? 

Scary, but yes it does! 

I just saw that in the spreadsheet for the hitch and forgot to add the weight to the axle. As I understand, the battery of 136#'s netted out 107#'s to the hitch, so adding 29#'s to the axle. 

Probably best to ask by showing to hopefully explain better.
* The first part is the Battery Distance x Battery weight / distance of hitch to axle. Resulting in 107#'s to the hitch and 29#'s to the axle.
* Second part is the new hitch weight x distance to axle / distance to load. Resulting in 253#'s to counter balance the 107#'s.

The second part is my worried about part.. 

Shame the cell colors don't come through..










Batteries

Battery box to Axe X


weight. W


Distance to load. L




123


136


66




Weight at hitch (WH)       X x W / DHA


Distance hitch/axle DHA


WH x DHA / L




107


156


Counter balance weight

253









W - WH






Weight back to axle


29

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Direct Link To This Post Posted: 17 Oct 2019 at 10:43am
If I understand the question, I think that is incorrect.  Remember that in a statics problem both the weights and the moments have to independently net out to zero. 

So say if you add 100 lbs 4 feet behind the axle and the axle to hitch distance is 13 ft then you have reduced the hitch weight by 100*4/13=31 lbs. So to net out the new trailer total weight the axle weight has to go up by 100+31=131 lbs. 

If instead you add the 100 lbs 4 ft in front of the axle then the hitch weight is increased by the 31 lbs so the axle weight only goes up 100-31=69 lbs. 

Make sense? 
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Direct Link To This Post Posted: 17 Oct 2019 at 10:05am
Originally posted by GlueGuy

Originally posted by jato

If I were to add 100 lbs behind the axle would it be the same, regardless if it is 12" behind or 48" behind, or is there another formula for this as well?  
No. With a longer moment, the effect on the CG increases. So adding 100 lbs 48" aft will have a much greater effect than 12" behind.

I get that part pretty well now. I believe Jato is referring to weight on the axle as making no difference. As he said, loaded behind the axle.

To that, I believe him correct. Makes no difference (that I can see) where it's placed (behind the axle) as far as just weight to axle.

If I'm wrong in this please correct. I want this spreadsheet right. 

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GlueGuy View Drop Down
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Direct Link To This Post Posted: 17 Oct 2019 at 9:40am
Originally posted by jato

If I were to add 100 lbs behind the axle would it be the same, regardless if it is 12" behind or 48" behind, or is there another formula for this as well?  
No. With a longer moment, the effect on the CG increases. So adding 100 lbs 48" aft will have a much greater effect than 12" behind.
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Direct Link To This Post Posted: 17 Oct 2019 at 9:22am
Originally posted by jato

I would like to see this completed worksheet.  Still fuzzy on the formula for the % of weight to add or subtract as relative to the distance from the center point, in this case, the axle.  If I were to add 100 lbs behind the axle would it be the same, regardless if it is 12" behind or 48" behind, or is there another formula for this as well?  

My approach to this (first is get it right) is to fully understand how I'm loading and what I'm placing for weight where and effect on my hitch (and of course axle).

By the example I did above. My batteries weigh 136#'s. With OG showing how to determine what is happening where (by moments) I can see 107#'s added to the hitch and only 29#'s back on the axle. 

As OG mentioned. If your TV can handle the additional weight, then your go to go and you increase your axle weight by so little.
I have a garage unit (182g) so a lot of my gear goes out back. To me, I put X#'s being that axle it's equal on the axle. I'm looking at 253#'s of gear behind the axle (in my storage area) to counter the additional I placed on the hitch. 
For me, right now I'm adding 282#'s on my axle. Not hard to load the gear back there. Heck, pretty close to just running with a full tank of fresh water for me..

I just realized I need another column for sub-totals..




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Direct Link To This Post Posted: 17 Oct 2019 at 8:59am
OG, I believe I mis-calculated my counter balance. I believe I should used: New hitch weight x distance to axle / distance axle to load area (behind the axle).

Thus, my added weight to counter balance is 107#'s, distance hitch to axle being 156" and load area behind axle being 66"

107 x 156 / 66 = 253#'s of gear to counter balance the added 107#'s on the hitch I added.

The 107#'s added to hitch comes from 136#'s of battery X Battery to axle 123" / hitch to axle 156"

136 x 123 / 156 = 107

I will get this right sooner or later... With your help of course! 
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Direct Link To This Post Posted: 17 Oct 2019 at 8:08am
I would like to see this completed worksheet.  Still fuzzy on the formula for the % of weight to add or subtract as relative to the distance from the center point, in this case, the axle.  If I were to add 100 lbs behind the axle would it be the same, regardless if it is 12" behind or 48" behind, or is there another formula for this as well?  
God's pod
'11 model 177
'17 Ford F-150 4WD 3.5 Ecoboost
Jim and Diane by beautiful Torch Lake
"...and you will know the Truth and the Truth will set you free."
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