New Andersen WD hitch

First blush is that the brake friction material in the ball/hitch head is
going to be both a maintenance issue and just like friction anti-sway bars. Getting
them wet, oil, wearing out the friction material, etc problems.

The way they do the WD is placing a new force on the coupler and wonder if the
coupler is designed for that kind of loading. Especially the pawl that holds
the coupler to the ball, as that is where the forces gets localized

Traditional cam'ed spring bars (round and trunnion) both hold back the amount
of off angle the trailer can move and increases the amount of spring bar tension
This has none of that and mainly works on the friction between the tappered ball
mount to the complimentary cavity in the hitch head.

As that 1/4" of friction material wears...does the ball shank then need to be
tightened?

What happens to the union of that tappered ball shank and cavity on a
whoopee-do when the tongues goes negative weight ? Is the nut holding
in the tappered ball shank have a spring to account for that situation?

That kind of force for each 'compliant' bushing has it held onto the tongue with
a clamping mechanism. Will it slip? How's about when it gets wet? Or oil gets
on there? That plate at the hitch head end also rotates in tandem with the
tongue...I'd think they would want it fixed to increase pressure on that
compliant bushing to prevent the tongue from swaying

Since the coupler is forced into the ball (that wear and whether the coupler
is designed for that kind of load) will it bang when the trailer brakes are
initiated to pull it the other way? What will that increased force do to the
compliant bushing over time? Will then bang back onto the coupler pawl when
the brakes are let go and throttle given?

Just some first glance thoughts...

Ben brought up the same things I was thinking about. My opinion is: I don't like the design at all. I don't see where it's any better than spring bars and I can see where it's worse in many ways.

I'll take the other side here guys... Rather innovative I think and a novel design... Admittedly, it's just another friction control device but rather well though out...

I suppose the brake material will wear some but that has yet to be determined how fast it will wear and how much replacement is...

My question is: how does one arrive at the same w/d pressures by just tightening the nuts on the end of the neoprene cushions... I would assume that in the instruction there is a guide to tell you how many turns equals X amount of pressure... IMO, if the hitch has any disadvantages, it is the tightening and untightening of the chains for weight distribution...

We're all always resistant to change, human nature being what it is, but I like the design of this hitch... If it works well, it jusy may become the defacto standard of those who tow with hitches like the dual cam amd Equal-i-zer... If it doesn't work well, it will fail and go by the wayside...

It's a rather neat design and I look forward to the first actual usage report by one of our members...

How about John, you gonna spring for one of these :W

Les

Don't get me wrong, as am a designer by training and in the heart. Love contraptions
of any kind...but...also by training look at how things fail in order to make
my designs 'good' to 'better'. Also lots of forensics from my own designs and
work fixing others design. Taught that Mr Murphy lives everywhere and to design
for the idiot and gorilla...as if it can go wrong, it will...

I've had some PE/ME's get into a Rube Goldberg situation trying to
design something marketing told them to. Easy to get myopic and
lose sight of the big picture and get caught up in a rat hole.

Les, the spring/bushings pull back on the plate below the hitch head ball and
that then pushes the tongue forward against the ball.

The contact point is inside the coupler at the pawl is my guess. Unless they
have a special coupler.

This is the leverage arm, I'd guess about 4 inches vs the Trunnion/Round bars
lever arm of 18"-20" times 2. That is a whole lot of PSI on that coupler pawl.
{edit}...okay, take this one back...the Trunnion/Round Bars do end
up in an area of about 4", so this is the same or no difference.

That is where I see a weakness, as am wondering if the coupler pawl is designed
for that kind of service.

Thinks like the surface area factored by the co-efficient of friction factored
by the moments (lever arm) telling to me that the amount of clamping force must
be huge. Plus the 'normal' recommended torque for any large ball (dia in the
2 5/16 range requires 500 ft/lbs of torque. Oh on that, the moment
on that friction material is the distance from the ball center line
to the trailer wheels

Then will the nut holding that ball shank back off with that kind of 'allowed'
rotation? As they allow the ball to turn along with the coupler (assumption)
and does the nut too? Then how do they manage the bearing and the loads on that
ball against whatever boss it rides on? Does it then need grease? If so, then
how do they manage from getting grease on/in the friction material mating surface?
It is right there

Allowing the ball to rotate along with the coupler and also having
to maintain something in the 500 ft/lb range requires a nifty bearing
setup. To allow the ball shank/nut to freely rotate and NOT back off
the nut, but to also maintain enough PSI on the friction material
to do it's job against that very, very long lever arm

Since friction material, assume it is the typical stuff I'm familiar with. I'd
wonder how well it does with the 'normal' banging all balls see during towing.
If it compresses does it go plastic or remains elastic? Will then wobble out ?

Heres a nice post from another site which explains some more.
Anderson Hitch post

Hi Ben,

Maybe I misunderstood your reply. You said the ball coupler pawl is where all the ball force is going to from WD, do you mean the front of the ball coupler or the latch on the back side of the ball is the pawl?

And you seem to keep referring to 500 ft. lb. of torque into the nut on the tow ball. Did I understand that right?

There is no nut on the tow ball. There is a 4.5 degree taper on the ball shank that sits in a female lined friction material socket that is part of the hitch shank. If you take the pin out of the chain plate on the bottom if the setup is unhitched, the entire tow ball will come right up and out of the shank socket.

I'm prepping my response, be back soon.

Thanks

John

(disclaimer, I'm not an engineer) I like the idea but there are a few areas I'm concerned about. On the video it is said there is 2000# on each chain. Are the clevis and chains shown strong enough for that much constant pressure, they seem small to me? Also, how do you know how far to tighten each chain. It's easy with the bars, once set up you always have the same number of links under load. Finally how does it work with heavier TW? I run around 1500#, with bars you get the size bar to match your TW, do these come in different sizes?

I still agree with Ben on this.

John !?!... you've got me !!!!

Cleaning out the garage and coming in to check this site, so apologize for the
quickie comments...

Well, lots of assumptions on my part.

Assumed the ball is held in there by a traditional nut, but will have to see
how they capture it

Thought a traditional coupler with a pawl, but in looking at the image...there
is no latch.

So how in the world did they get the ball past the interference fit?...but that
is another assumption...that the coupler has an interference fit for the ball
like these images:





so if traditional, then that pawl will take the forces...but...since not traditional
how do they keep the ball from coming off?

By interference, meaning that the coupler has a lower hemisphere smaller
in dia than the ball dia. The pawl moves out of the way to allow the
ball to move backwards and then drop out.

Ben,

See this video, http://www.andersenhitches.com/Catalog/andersen-nosway-weight-distribution-hitch.aspx

It shows the tapered ball shank coming right up out of the shank socket.

Now to the coupler... OK you saw something I did not. The gray mocked up frame has no latch....duh???

But in that same video you can see a Dutchmen TT on the back of a F250. The Dutchmen has the standard TT sliding latch. I think the gray demo frame is a computer model and not a good on at that.

OK now I know what you mean by safety pawl. Are you saying the WD forces on the tow ball are going into the back half of the coupler into the safety pawl? If so, I didn't see it that way. I see them going forward into the front of the coupler sphere. Trying to make sure I understand your thought process.

Still typing my thoughts on the hitch..

John