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Old 09-10-2012, 01:30 PM   #547
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Hi mstephens,

Thank you for letting us know that Andersen responded to your email quickly with the questions you had.

You mentioned that in your opinion, some users would benefit from a more traditional WD set up, while others using or considering the Andersen hitch might need to adjust the weight of the chains to include heavier chains (6000 lbs of strain).

For those of us that are physics challenged and are driving SUV's to tow our AS's, how would we calculate to know if we have the right size chains? Or is this question something that would be better answered by us making a phone call to Andersen directly?

I like the idea of the Andersen hitch but it sounds as though we might need to "tweak" a few features for maximum durability and safety.

From your calculations, am I correct in assuming this?
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Old 09-10-2012, 02:30 PM   #548
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After doing a complete inventory of parts, my hitch is missing a major part, the ball, it's mount, and it's retaining ring.

And, the dealer I bought it from does not answer the phone.
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Old 09-10-2012, 02:50 PM   #549
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Quote:
Originally Posted by sierrafun View Post
Hi mstephens,

Thank you for letting us know that Andersen responded to your email quickly with the questions you had.

You mentioned that in your opinion, some users would benefit from a more traditional WD set up, while others using or considering the Andersen hitch might need to adjust the weight of the chains to include heavier chains (6000 lbs of strain).

For those of us that are physics challenged and are driving SUV's to tow our AS's, how would we calculate to know if we have the right size chains? Or is this question something that would be better answered by us making a phone call to Andersen directly?

I like the idea of the Andersen hitch but it sounds as though we might need to "tweak" a few features for maximum durability and safety.

From your calculations, am I correct in assuming this?
Always get as much information as you can. Calling hitch makers and describing your vehicle and trailer is a good thing to do.

It is also good to confirm as much as you can with your own investigations. As for an SUV and the Anderson, let me describe how I would make the calculations, and maybe it is useful to you as an example.

I measured from the center of my front wheel (that would be where the axle attaches) back to the center of my ball. I got 192". Now I would measure from the center of the ball down to the plate that holds the chains. I don't have one, but it looks to be about 10" - maybe less. For this EXAMPLE, I will call it 10".

Those two measurement provide the "leverage ratio". Dividing 192/10 I get 19.2 as the answer. That means my leverage ratio is "1 to 19.2" which we express as 1:19.2 What is means is that if you want to put a 100 pound force on the front axle, you must put 19.2 times that force on the bottom of the hitch to rotate it towards the front. That's how you transfer weight from the back to the front - you rotate the hitch ball clockwise with TORQUE. In this case, pulling on the chain provides he torque to rotate the hitch about the ball center.

So, to distribute 100 pounds onto the front axle from the back, I have to apply 100 X 19.2 pounds, or 1,920 pounds of force to the bottom of the hitch through the chains. Let's round it up to 2,000 pounds. Now, I have 2 chains, so that is 1,000 pounds per chain. Since we are pulling on the chain, this is called a "strain force."

The chains that come with the hitch are rated to work at 2,000 pound each. So, roughly speaking, pulling at half that rating is pretty much within a good safe margin.

By that sample calculation, I could transfer 100 pounds. Not bad, but with my own setup, I would need to transfer more than 100 pounds. I need to transfer more like 250 or 300. Let's see what would happen if I choose 300.

I would need 300 X 19.2 = 5,670 pounds of force at the bottom of the hitch. Dividing that between 2 chains, I would have to pull each chain with a force of 2,880 pounds. That is way over the working limit of the chain. In such a case, I would want a 4,000 pound working limit chain.

So, you can perform this calculation in less than 5 minutes at home. Be sure to measure the ball to plate carefully and accurately, since an inch or so will make a HUGE difference in the final calculation.

Now, part II of this is knowing how much you really need to transfer. There are two main variables. First, how much the tongue weighs. This is usually a number between 450 and 1000 pounds or so. Then you need to see what happens to your SUV when you hang that on the ball as a dead weight. This is where some ART is mixed with some SCIENCE. In general, the more your vehicle sags with the dead weight tongue, the more you will need to transfer to the front.

My SUV sags a lot with my 800 pound tongue. So, I need to shift quite a bit to the front. The more I shift, the less my SUV sags. Why is this important? Because as your vehicle becomes rear heavy, the front wheels become lighter and lighter, and seem to be wanting to "lift off the road." This "light steering" makes it harder to control the rig. The simple answer is to shift weight forward over the front wheels to "increase the steering force."

So what do we know?
  1. The amount of weight shifting you need will depend on TV and trailer
  2. The amount of shift you can get with a hitch of any kind can be calculated with a few simple steps
  3. Not all hitches will shift the same amount of weight
  4. Long wheelbase and soft suspension is harder to properly shift than shorter wheelbases with stiffer suspensions.
  5. Manufacturers can help you pick the right hitch for your TV, and you can add your own verification
I hope that helps a little.
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Old 09-10-2012, 02:56 PM   #550
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OK here is a number that you all can work with.

The bushings require a 1,500 lb load to compress them 1/4 in.

I am not in a position to hook up today and actually measure the compression on my trailer but will do that ASAP. In the mean time keep in mind I am working with a 34 ft trailer and a Ford Excursion, heavy trailer and big truck.

While I do not expect any designer job offers directed at "posters" to come out of this discussion it is clear that Andersen is aware of our experiences.
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Old 09-10-2012, 03:30 PM   #551
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Quote:
Originally Posted by sierrafun View Post
From your calculations, am I correct in assuming this?
No you can not. Yes there are comments posted here by "user" have pointed out operational consideration, none of which should cause one to discount the hitch when compared to the operational considerations of other WD hitches.

This hitch has a warranty that would cover any of the considerations should they ever become a problem.
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Old 09-10-2012, 03:54 PM   #552
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Quote:
Originally Posted by dkottum
kosm1o, did you drill holes through both sides and put a 3/8" bolt in? My Andersen will be here any day.

doug k
Yes, through both sides with lock washer and nut.
The oher issue I had is with the stinger. There are holes for adjustment every 1.5 inches but there is a 3 inch void when you flip the stinger. I wanted to be lower one way but when i flipped it, it was too low. I had to drill another hole to get the ball height where I wanted it. You might not that problem.
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Old 09-10-2012, 04:45 PM   #553
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Founds some scale numbers on another forum: RV.Net Open Roads Forum: Towing: New Andersen WD hitch

TV: Pilot TT: lance 1575

The tongue weight of the trailer is 400# total trailer weight it 3440# Unloaded

Front TV axle weight Rear TV axle weight

no trailer: 2520# 2180#

w/trailer: 2320# 2780#

w/ WD 2500# 2520#

The trailer axle went form 3044# with the the WD to 3120 with the WD hook up..

"You will notice a 20 lb. discrepancy in the figures. Nothing changed in either the TV or TT that would cause that. I am surmising that the CAT scale weighs in 20 lb. increments and that maybe the rig was right on the bubble."

He does not state how much compression but does talk about threads. This doesn't tell us anything as everyone can start with a different amount showing when they start to tighten the chain..
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Old 09-10-2012, 04:53 PM   #554
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CAT scales do weight in 20lb increments...one in a while you get the 20lbs off thing.
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Old 09-10-2012, 05:07 PM   #555
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The scales show a few things.

He has a tongue weight of 400 lbs. That weight is distributed -20 lbs to the front axle of the truck +340 to the rear axle of the truck and + 76 lbs to the trailer axles. Not a bad ratio for that light a trailer.

If he finds he has a steering issue, from the reduced load on the front axle of the TV , he could add some more weight to the front axle of the TV and the trailer by tightening up a bit more on the bushings. Any weight add to these axles will reduce the load on the rear axle of the truck by an equal amount.

Kind a looks like the hitch is doing what it is supposed to.
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Old 09-10-2012, 05:13 PM   #556
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I found a later thread that said he had 1/16 of an inch compression on the bushing..
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Old 09-10-2012, 05:48 PM   #557
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Here is some more useful information. From the same user as above "Bruce H"

A new Weight Distribution Hitch (WDH) - Topic

His chart is a little off, but he says it's not perfect.

You will also notice that he bolted the Andersen hitch to the frame instead of using both side brackets. This could eliminate the movement of the brackets on the frame. It looks like he used the set screw hole and the one above that to do this.

The only drawback I can see are holes in your frame. Can anyone else think of another drawback??

This guy did his homework and didn't do napkin engineering with numbers. He used real world numbers and had a hitch to work with..

These are some numbers that we can start to use, even though they are a little off.
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Old 09-10-2012, 06:13 PM   #558
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Hats off to that camper. Now I can't wait to hitch up and measure my bushing compression.
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Old 09-11-2012, 06:56 AM   #559
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Here is a question for you engineers that are keeping up with this new Andersen hitch. I have read in threads about using a hitch such as the Equilizer that uses weight distributing bars of various strengths. Users have been warned not to use a size that is too large for the job as there is a danger of bending the A frame, particularly when towing through a large dip in the road as one might experience going into a gas station from the highway. Going through that dip causes, as I understand it, a lot of strain on the frame because of the way the bars are leveraging the weight distribution. Since the Andersen accomplishes this using a horizontal force, rather than a vertically downward force, is the danger of bending the A frame lessened ? or the same ? or greater?
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Old 09-11-2012, 08:18 AM   #560
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Quote:
Originally Posted by Kosm1o View Post
Here is a question for you engineers that are keeping up with this new Andersen hitch. I have read in threads about using a hitch such as the Equilizer that uses weight distributing bars of various strengths. Users have been warned not to use a size that is too large for the job as there is a danger of bending the A frame, particularly when towing through a large dip in the road as one might experience going into a gas station from the highway. Going through that dip causes, as I understand it, a lot of strain on the frame because of the way the bars are leveraging the weight distribution. Since the Andersen accomplishes this using a horizontal force, rather than a vertically downward force, is the danger of bending the A frame lessened ? or the same ? or greater?
Not an engineer!
I have never heard of an "A" frame bending, lots of warnings, no bending. it will beat your trail up though.

This is one reason for the rubber bushings. I felt all the dips on the road with my regular WD and the creaking going in and out gas station and big dips with all the extra strain and force being put on it.

With the Andersen, the Rubber bushings take that extra force up, and you don't feel it on the dips in the road anymore. It makes for a much smother ride.
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