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Weight Distribution hitch

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Rpod-Couple View Drop Down
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Post Options Post Options   Quote Rpod-Couple Quote  Post ReplyReply Direct Link To This Post Topic: Weight Distribution hitch
    Posted: 20 Nov 2021 at 9:36pm
The WDH bars are 1” diameter making a cross sectional area of 0.785”. The yield point for mild steel is about 50,000 pounds-per-square inch  x 0.785 inch-squared = 39,000 lbs for each bar. I don’t see how 600 lbs spring bars are going to yield anywhere near 1200 lbs. They have a huge safety factor. 

I have run this on-line WDH calculator and everything is in the green for my CX-9, with 600 lbs WDH, and R-pod 171. https://www.ajdesigner.com/apptrailertow/weightdistributionhitch.php



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offgrid View Drop Down
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Post Options Post Options   Quote offgrid Quote  Post ReplyReply Direct Link To This Post Posted: 21 Nov 2021 at 3:23am
The link to the towing calculator is down at the bottom of my post.

Re when the spring bars will fail you need to consider them as if they were cantilevered beams, fixed at one end with a point load at the other end. That beam configuration has a moment at the fixed end of M = F x d. d is 18 inches and in my case F is about 750/2 = 375 lbs (2 bars) , so M = 6750 in-lbs.

Assuming a 1 inch bar, the section modulus is 0.098 in^3 so the stress is M/S = 6750/.098 = 68 ksi. Way past the yield of mild steel. And that is before we add a 2x factor to handle 2 g bump loads, which are common.   

I don't have my trailer or wdh anymore but I'm sure the bars on my 1000 lb wdh were larger than 1 inch dia. Unlikely they are mild steel either, spring steels are around 100 ksi or better in order to not be to stiff in deflection. I did eventually find a statement that my bars were rated at 1000 lbs each max.

In any case, the point is that you can for sure bend your wdh spring bars under bump loads if they are too light for the application. So run the calculator for your actual load case and get wdh bars rated for that. Might be 600 lbs for a light rig but not for a heavier configuration set up for boondocking. In my case an 800 lb rated wdh would have worked but been marginal. The ride was quite comfortable will 1000 lb bars so I went with that. And you are not going to bend your TV frame by using a wdh with a higher rating because if you have it set up properly the max load on the bars, frame, and trailer will be the same regardless of the wdh rating.
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Post Options Post Options   Quote smedleyludlow Quote  Post ReplyReply Direct Link To This Post Posted: 21 Nov 2021 at 8:56am
Originally posted by TheBum

Originally posted by Colt

Originally posted by richfsi

Greetings, just purchased a 190. I am towing with a 2019 Toyota Highlander. Looking for a recommendation for a Weight Distribution Hitch. Appreciate the help!


Isn't the Highlander built on a unibody? Are any hitches built for it that are built for weight distribution?    

My SUV and 180 does not need weight distribution, nor sway damping, but I use a friction sway damper just in case. It is a unibody and nobody makes a weight distribution rated hitch for it.

Yes, but I towed my 179 many thousands of miles with a 2012 Highlander and a 600/6000-lb E2 hitch and never had an issue. I think the issue comes if you oversize the WDH.

We tow a 2017 Rpod 176 with a Hyundai Santa Fe Limited Ultimate ( 5k tow capacity) and are soon acquiring a 2021 No Bo 16.6.  It has a unibdy that I use a Camco R3 Recurve WDH with 400 lb bars.  As such, I only put a couple of hundred pounds of weight distribution on the lightweight bars.  There are no prohibitions by Hyundai that I can find that say not to use a WDH. and my hitch is rated for 6000lbs and a WDH.  The main thing with a WDH is not to go over/through large dips or inclines that create a vertical angle between the TV and trailer.  This creates a great strain on the unibody, the spring bars and the trailer frame.  Hence the 400 lb bars. They will flex rather than break something.  
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