Coast Resorts Open Roads Forum: Towing: New Andersen WD hitch

Print | Close

Topic: New Andersen WD hitch

Posted By: JBarca on 02/01/12 07:17pm

Hi Gijoecam,

I am trying to follow your words and unfortunately I can create at a few possible combinations from the wording.

We are OK with a hand mocked up sketch to get the point across. Go for it.

Quote:

In my opinion, a better design for this setup would use a pair of arms extending from the ball below the coupler parallel to the trailer tongue that the chains would connect to.

Need a few more words to help "a pair of arms extending from the ball below the coupler parallel to the trailer tongue"

The tow ball in this case is made of a ball sphere attached to a long tapered shank. I have "estimated" the shank may be 8" long below the ball sphere. Again a hand sketch here really helps.

How far down from the ball sphere are you attaching? 1/2" or 6"?

Are the long part of arms attached at a 90 degree angle to the ball shank center-line when viewed from the side of the A frame?

Approx how long are the arms?

Parallel to the tongue. Again lost which direction. Parallel to the ground? Parallel to the 50 deg inclusive angle of the A frame ( the V of the frame) or both at the same time? Or parallel to the ball shank which is parallel to the front vertical surface of the tongue?

Quote:

Tightening these chains would try to pull those arms down and into compression against the ball-end, the same as the current setup pulls the trailer tongue.

Then, since the resultant force will be down on those arms, simply hool the ends of those arms over top of the frame rails. That would allow the resultant force applied to the trailer tongue to be only downward instead of forward and down, and since the whole assembly would still turn with the trailer, the sway-control inherint in the Andersen design would still be retained with little or no movement of the ball relative to the coupler.

We need to know more on how bars are attached to the ball.

Interested in your idea, just cannot visualize it to line up with the wording of the 2nd paragraph.

Thanks

John

John & Cindy

2005 Ford F350 Super Duty, 4x4; 6.8L V10 with 4.10
CC, SB, Lariat & FX4 package
21,000 GCWR, 11,000 GVWR
Ford Tow Command
1,700# Reese HP hitch & HP Dual Cam
2 1/2" Towbeast Receiver

2004 Sunline Solaris T310SR
(I wish we were camping!)

Posted By: gijoecam on 02/02/12 08:04am

JBarca wrote:

I'll see what I can scratch-out during my lunch break.

Quote:

Below the ball itself, above the 'shank', between the coupler and the top of the opening that the ball/shank assembly drops into.

Quote:

Are the long part of arms attached at a 90 degree angle to the ball shank center-line when viewed from the side of the A frame?

Yes.

Approx how long are the arms?
The arms need to be long enough to reach the point on the trailer frame where the brackets would in the standard setup.

Quote:

Parallel to the tongue. Again lost which direction. Parallel to the ground? Parallel to the 50 deg inclusive angle of the A frame ( the V of the frame) or both at the same time?

Both.

Quote:

Or parallel to the ball shank which is parallel to the front vertical surface of the tongue?

Perpendicular to the axis of rotation of the ball shank.

Quote:

We need to know more on how bars are attached to the ball.

That would take some more engineering... I'm thinking off-hand, a flat plate, similar to the one on the bottom that the chains attach to with roughly the same two holes in roughly the same location. Then, the end of the stanchion would have a yoke that would extend to the top and bottom of the plate, with a pin that drops through the yoke and plate. At the trailer end, it would take some more thought... I have some rough ideas, but it would take some more sketching. The bottom line is that you would use the stanchions to redirect the chain forces from horizontal to vertical, instead of using the trailer tongue to bear both the horizontal and vertical components of the force. (If I get time, I'll explain using some simple force vector drawings)

Hope that helps in the interim... I'll see what I can do later if/when I get time...

Posted By: BenK on 02/02/12 10:19am

Let me take a stab at your idea with my verbiage and new ideas...

Keep the basic architecture of the Andersen system, but change the ball/shank

As part of the ball/shank include a 'new' plate that is just below the ball.

That would then become the point of contact for the WD forces, which
would need a mating surfaces between them that would stand the
dynamic forces & pivot vertically to allow the WD to work.

That mating part could be part of another weakness solution of the Andersen system

The way Andersen clamps to the tongue is another weak design.

A cross member solves that. Have a longer than needed cross tube that is to
be sized and cut to length for each install. The clamps to the tongue now won't
have to hold it from sliding. As the cross member cut to length becomes an interference
fit wedging in the 'V' of the tongue

That would then have an extension up to the ball/shank to become the 'mating'
interface

The ball is literally just along for the ride in regards to the WD
forces. It then becomes a secondary or a safety for the connection
between the TV and TT

The ball shank bottom would remain the same

How does that sound?

The vector diagram needs to be generated, but this first blush of
a modification to the Andersen design looks good...but a bit of NIH
here as usual... [emoticon]

Posted By: BenK on 02/02/12 10:51am

Heck, an improvement !

Instead of having to deal with a cross member per say...how's about a plate that
takes the cross member's forces, is the clamping platform, is the base of the ball, etc

It would look like a triangle

At the ball shank, there needs to be a vertical pivot that is good for the forces. This would also need to have an easy removal, as that
is one of the specifications...easy of unhooking & light.

Can also be a fabricated assembly instead of a plate, but think a plate less
cost. Maybe a bit more weight, but the Andersen design is already several hundred
pounds lighter

OBTW, public, so these ideas and improvements are public... [emoticon]

Posted By: rexlion on 02/02/12 03:11pm

"Several hundred pounds lighter"? The Andersen weighs under 60 lbs. But the 14000/1400 Equal-i-zer hitch has a shipping weight of 109 lbs. Oh, I just had a thought, maybe you're referring to a Hensley or something?

I'm not smart enough to visualize the improvements, so I hope someone can do a drawing.

Posted By: Campin LI on 02/04/12 09:07am

JBarca wrote:

Campin LI wrote:

It looks like the ball that comes with the hitch is round at the top. Back to the first post with the link to their web site. Looks like you have to use that ball because it is part of the system. On their web site scroll down to the picture that shows it and click on the picture to enlarge it.

Hi Campin,

H'mm good point as I too now remember that image of a complete round sphere. Like this one?
[image]

However I think we have been computer model tricked again. Those parts are suspended in mid air and a good 3D CAD program can look pretty real now a days. That total round top ball may be the CAD tech just left off the flat top. If you look at the hex head bolts on the shank there are no bolt grade stamp markings. It is a solid model image not the real thing.

See these pic's, this is a pic and not a computer model. It is the actual manufactured part, not a sales promo. These are clips off their video. Look at the flat spot on top of the ball.
[image]

Now that I see that flat spot on their tow ball it makes me question why is it there? Even my 1/2 a dozen 2" draw bars with 2" balls have a flat spot on the top. A thought is that the flat spot is machined in on purpose to not have the trailer tongue weight press exactly down on the coupler and ball center. Since it is machined off the tongue weight is moved to the outer sphere to support the load.

There is some intentional reason the ball has a flat spot on top. It is an additional setup step to machine off that flat. Any one know the reason?

Hope this helps

John

Missed that. Never noticed the floating hitch either. Computers are good but still not as good as a real picture.

Posted By: Campin LI on 02/04/12 09:15am

Thought I would bring up a little issue. To me, this Anderson hitch does not work like a traditional weight distribution hitch. A true weight distribution hitch has spring bars that act like levers. They lift the back of the truck and distribute weight to the front of the truck and the trailer. This hitch does not do that. It looks like all that happens is you shorten the chain through adjustment until it is short enough to make a rectangle using the hitch head, the chain, the bracket for the chain on the trailer and the frame of the trailer. The tongue on the ball is the hinge that allows pivot until rectangle shape is present. I see that the latch would have pressure but probably not much since the weight of the trailer tongue is pushing down right there and that would keep it seated. The chain is in tension. The weight of the tongue stays on the ball which means it stays on the back of the truck.

I think this is more like a substitute for air bags because it does not look like weight distribution to me. Maybe I am wrong or missing something?

* This post was last edited 02/04/12 02:25pm by Campin LI *

Posted By: rexlion on 02/04/12 03:35pm

Campin LI, it is distributing weight when the chain is tightened. However, the "lever" is the rather short ball mount. Granted, the system cannot travel much past perpendicular (the rectangle you refer to), but that is because the lever is too short to move it much farther against the opposing leverage of the truck's wheelbase. Did you see BenK's drawing on page 2? I found it helpful for seeing the forces involved. If the truck wheelbase were only, say, 2 feet, one can see how the ball mount could be pushed way past perpendicular given enough chain take-up.

Posted By: Campin LI on 02/05/12 06:45am

BenK wrote:

Using Bens diagram above, I agree the frame of the trailer is pushing towards the tow vehicle when the chain is tightened. No question.

I believe the bottom arrow is wrong. When the chain is tightened, it does not know it is tightened from one side. It is in tension and therefore pulling both sides, so the arrow should go both ways to demonstrate forces in both directions. The hitch ball is the hinge. You tighten the chain until the rectangle is formed. Once the rectangle is formed, the truck and trailer are leveled. This action also causes the hitch ball to rotate toward the truck which would set the pressure from the hitch pawl lower on the ball. I suppose some weight might be transferred forward but not knowing the math involved, I don't know how much is. I don't see any lever because the chain is not rigid, even its mount to the plate is not rigid. Technically, that is a hinge too. To me it looks like you tighten the chain and this action lifts the trailer tongue and hitch ball. I see that by over tightening the chain, the back of the truck would be lifted higher and that action would distribute weight forward, so I guess to some degree it does distribute weight, just not traditionally by prying.

Anyway, I'm not sure. Just throwing it out there.

* This post was edited 02/05/12 07:06am by Campin LI *

Posted By: red31 on 02/05/12 08:23am

When the TV-trailer connection goes from \/ to /\ (exaggerated) by tightening the chain, the trailer tires and TV front tires are supporting more weight than before the chain is tightened.

Print | Close