Andersen Ultimate not working for me

http://www.andersenhitches.com/uploads/Ultimate%20GN%20Dimensions%203220%203225%20Mar%202015.pdf

Cut and paste the dimensions of the unit.

Per Dave of Anderson customer service: "The pin box coupler block can be rotated 180 degrees to eliminate the extra 4" offset that it creates. We do not like to see the pyramid base itself rotated as most vehicles has a cross member to the frame we are trying to keep the pressure over." This was as of 1/25/16, I doubt much has changed since then.

Just an FYI, flipping the pin box coupler actually moves the connection point 8" as the center to center of the king pin to ball location is 4". But either way, front or rear, it would be 4" offset from the king pin.

And again (LOL) when you figure the geometry of the load going rearward (acceleration or hills) or forward (deceleration, braking) on the hitch how do you figure this law of physics only applies to the Anderson? You have the same physical action with a Reese, go up a hill the force on the hitch goes rearward. Hit the brakes the force goes forward. And statically they will all be the same. The weight is spread out over the base.

Ok, went in the garage and measured my Suoerglide. I have 21" center to center on the rails. 3.5" from center of front trail to center of pin, hitch height is about 13".

For a 1000 pound pin load, 167 pounds goes to the rear rail and 833 pounds on the front rail.

Every hitch will be different, but this shows how different it can be.

Bobandshawn wrote:
Best contact Anderson about flipping that hitch. Big no-no they told me.

Which version you have? GN or rail? Andrrsen manual for the rail version clearly states its OK to flip.

Best contact Anderson about flipping that hitch. Big no-no they told me.

I think I am going to go measure my Superglide and run through the numbers the same way to see how similar or different it is.

From a basic geometry standpoint it makes sense to me that the rail closest to the ball is going to carry more of the weight in a static (parked) situation. But once you start moving that's all out the window. Going down the highway I think the rear rail is going to take the bulk of the load regardless of which way the hitch is positioned. Hit the brakes and I bet the bulk of the load shifts to the front rail. I think this is probably also true of a standard fifth wheel hitch as well.

What would be interesting is if somebody with an Andersen hitch (like me) and some spare time (unlike me) would take their trailer to a scale and see what sort of difference the base orientation has on axle weights. My guess is the difference wouldn't be too dramatic.

Just FWIW, I have my Andersen in the exact configuration (hitch oriented back, kingpin in front of ball to my pinbox clears) and I have no issues with wagging or movement at all. Compared to my Curt slider the Andersen is rock solid. That being said, my trailer isn't very heavy (10.5k gross) and I've got 1200 lbs of Cummins sitting over my front axle so even if the Andersen does tend to shift the load toward the rear more than others it probably doesn't matter in my setup.

wvcampers wrote:
I have not weighed using the Andersen to see if the weight has shifted.

Purely speculative, but I am guessing that the combination of the weight being pushed further back on the truck, combined with the distance back to the connection point for resisting lateral loads being pushed back is causing your wag. I bet it is pushed back enough that you are getting a bit of tail wagging like you could have with a bumper tow. That lateral load has more of a lever to move the truck with.

Just a guess.

I'd really be curious to see what the scale numbers with the Anderson would be. It would be cool to see you weigh with both hitches on the same day to have it at a 100% apples to apples comparison with no changes in trailer weight. I am guessing that is too much hassle though.

Sport45 wrote:

Cdash wrote:
If someone can measure distance center of rail to center of rail, and distance from center of pin to center of rail, I can tell you how much more is pushed either forward or back.

Will this work?

Perfect!

I am going to reference numbers off the picture using right and left (as it is shown in the picture). The rotation of the base in the truck will determine weather the loads I provide are fore or aft of the truck axle.

Here are the numbers:

For a 1,000 pound vertical load on the ball the right rail would see 708 pounds and the left rail would see 296 pounds. Or to simplify it for a known pin weight: 70.8% of the pin load to the right rail and 29.6% to the left rail.

I think fixed fifth wheel hitches would have a 50 - 50 distribution if the pin center is centered between the rails. On sliders, the distribution will probably put the majority of the weight on the front rail. I'd have to measure to get exact numbers, but my Superglide would put the majority on the front rail.

The horizontal load, which others have pointed out will exist in any type of hitch, but giving numbers just to give you a point of reference:
A 1,000 pound horizontal load on the ball applied towards the right looking at the same picture will result in 656 pounds downward force on the rear rail and 656 pounds upward force on the front rail. If you have it at the highest (18" setting) it will be 750 pounds for every 1,000 pounds.

So putting both of these together could quickly put all the vertical pin load on the rear rail, aft of the trucks rear axle. Whether that is or will be a problem, is anyone's guess. Most seem to do fine, but if not, I would think these numbers could provide some insight. To be fair, similar things will happen with a regular fifth wheel hitch, but not to the extent of an Anderson base oriented to provide maximum cab clearance. The simple way to say it is "You can't move the load further back without the load being further back".

In reality, I don't think there is any good way to ever know what the horizontal force would be. It would depend on speed, wind velocity and direction, grade of road, alignment of axles, tire inflation, etc. If I were guessing, I would expect that horizontal load to generally be around 25% of the trailer weight, but I am just completely guessing.

So in summary, the message I would like people to think about is what they are trying to accomplish. If they are using it because physical reasons favor a lightweight hitch, great. If they are using the Anderson with the ball closer to the cab, then I don't see much potential for issues. If someone has a bit too much trailer for the truck and are trying to preserve payload by having a lightweight hitch, that is fine. But by orienting that hitch to provide maximum clearance while you are close or over on weights "could" lead to having some handling issues due to how the hitch transfers load aft of the rear truck axle. Just something to consider when making your hitch decision.

And for the record, the Pullrite Superlite hitch that is similar to the Anderson, looks to have the ball centered between the front and back rails (can't find actual dimensions to verify this), so it would load the rails more similar to a conventional hitch with a 50 - 50 front/back distribution. Te two companies are providing a similar product, but have taken different paths to the final product. I would assume that each has their reasoning for what they did.

Cdash wrote:
If someone can measure distance center of rail to center of rail, and distance from center of pin to center of rail, I can tell you how much more is pushed either forward or back.

Will this work?

I often wondered about the dynamics with the rail mount hitches in general...when you add the total drag of the trailer ( wind resistance and rolling resistance) what is the weight transfer during travel to the rear rails?

I know this doesn't' affect the dynamics of the pivot points and sway, but the center of weight distribution must move more to the aft rail during highway speeds?