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

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Topic: New Andersen WD hitch

Posted By: Ron Gratz on 01/30/12 04:50pm

JBarca wrote:

Let me show and explain and you tell me where I go wrong or we have agreement.

EDIT 1-30-12 A point to clarify, we need to declare if the tongue jack is up or down supporting the TW when tightening the urethane springs. Odds are higher that the jack is down supporting the tongue.

If the tongue jack is up, then it depends on the stiffness of the rear springs of the truck in relation to the TW if the tongue will rise or the ball will drop.

My analogy of the coupler rising was based "no" jack being down and heavy truck suspension in relation to TT TW. That may not be a real condition in most cases as even I have the jack down... but it was how my brain was thinking about it at the time. And may be where the mix up of which part is moving up or down...LOL [emoticon]

This is why diagrams are better then words most time... Put the tongue jack in the equation [emoticon]

I fail to see how the tongue jack makes any difference. As the chain tension increases, the forward thrust of coupler against ball increases. Whether the coupler then moves upward relative to the ball simply depends on the net direction (up or down) of vertical forces generated between coupler and ball. And those forces depend on shapes of the contact surfaces between socket and ball and between latch and ball. I don't think we can unequivocally say that "If the chain forces are high enough they will overcome the down force of the TW and the coupler will cam itself up."

Quote:

If we are in agreement here, (Yes/No?) then this comes down to the WD chain force.

Okay, let's assume the diagram for your specific coupler accurately depicts the relative positions of ball and coupler components with springs tensioned. Then I also assume there must have been a gap between ball and coupler latch before the springs were tensioned. The tensioning of the springs then caused the coupler to move forward and upward (relative to the ball) until the coupler latch was firmly in contact with the ball.

Given these assumptions, I would guess that a relatively small forward thrust, perhaps equal in magnitude to the TW, would cause the coupler to ride up and over the ball to close the gap between ball and coupler latch. The relatively small force requirement would be due to the relatively flat slope of the socket/ball contact surface as you have depicted.

But, before becoming a completely agreeable person, I have to ask --
Is your coupler latch adjustable? If so, why should there be a gap between ball and coupler latch prior to spring tensioning? If there is no gap after the coupler is latched, the coupler latch cannot move forward relative to the ball and the coupler cannot rise up relative to the ball.

Also, even if what you have depicted for your particular coupler is an accurate representation, I'm sure there are many other coupler configurations which would produce different results. So again, I must believe we cannot be certain that coupler "lift" will occur.

Quote:

The invite hint, hint was to help confirm that on my TT and TV to use as an example, that the force needed to be generated in the Anderson WD chains total would be approx. 7,800# to create what I declare is proper WD on this truck.

I have a 1,400# loaded TW, I run the WD so the front of the truck is approx 100 to 150# light on purpose. Partly due to 2 stage rear suspension that this truck is more stable when the helper springs just kiss the truck bracket and for the new SAE recommendation to help ward off oversteer.

I did not do the moments yet to confirm the reactions however if I was in the right league of 7,800# force pulling on an estimated 8" Anderson tow ball creating the 5,225 ft. lb of torque needed into the receiver for proper WD on the TV, then the 1,400# raw TW was not enough to hold down the TT tongue from not lifting "up" that 1/8".

Did I mess up seeing this?

PS the invite is still there on the WD chain force....LOL

John, I think you were in the right league with your chain force calculations. And, given the characteristics of your specific coupler (including the gap between ball and coupler latch), I agree a combined chain tension of 7800# certainly would cause the coupler to move forward and rise the 1/8".

However, although the Andersen hitch is rated for a TW of 1400#, I really doubt that they expect the hitch to generate enough WD torque to restore all the front end load which would be removed by a 1400# TW. And, if you're driving a 2011 or newer Ford truck, you only need to restore 50% -- according to Ford. [emoticon]

Ron

Posted By: JBarca on 01/30/12 07:27pm

Hi Ben,

The picture I was showing Ron was a representation of the coupler trying to get a specific point across. Which was with "my" coupler when the Anderson hitch had fully tensioned WD, the ball would be firmly pressed into the latch and clearance exists on the front of the ball inside and on the top front. No clearance exists at the latch. OK more on that in a moment in the next reply.

To help show how this Shelby 5104 Class 4 coupler is created... See this. This may help. An updated diagram with all parts shown except the torsion spring. Unless someone else can find an on line or scanned cross section this may be all we get.

This is my perception of how the Anderson hitch will locate the tow ball into the latch when WD is tensioned. Sketch has full latch details expect spring. (sorry, no spring... [emoticon]

)

This coupler latch lock lever does not work like any of the 3 in your last post. Those couplers have the latch lever that pulls up in more of a vertical direction and you pivot the lock lever down to lock or screw the knob on the really old ones. I have not seen one of those screw jobs in a really long time.

The Shelby 5104 has a sliding lock lever. No pivot up action. Here is a progression of the sliding lock lever.

Lock lever fully back towards TT. Ball coupler fully unlocked. (open)

[image]

Sliding locking lever half way slid forward. Closing in progress.
[image]

Sliding lock lever now fully locked and down. I pin the pad lock hole while towing.
[image]

Now to open the coupler to allow the ball to come out, here is a side view.
[image]

The ball will move down and out of the coupler in a pattern as shown by the blue center line.

See looking up with no ball. The latch is withdrawn far enough the hole is large enough that the entire ball can come out. (Once weight is off and truck or TT can roll a little bit)
[image]

Here are 2 pic's looking down with the coupler open
[image]

You can just see the torsion spring.
[image]

Now lets look inside, or at least the rear of the coupler. Sure glad for digital pic's LOL....as I took about 30 pic's to get these 2. Not a lot of room in there with a jack post, 7 wire cable, jack power cord and a few DC brackets...

The coupler latch is open. You can see the latch pin full back.
[image]

Now fully locked. See the witness line of the latch pin how it traveled and the feet that have locked into the coupler housing of the latch lever.
[image]

OK now the contact patch, it exists on the top rear of the ball and coupler. It is there.
[image]

I have 1/8" vertical (total) and 1/8" front to back (total) clearance on this coupler. Technically if I was in the exact middle of the clearance holding the ball I would have 1/16" air space all around the ball.

The dome on top if large enough and the coupler is 0.200" thick. If the ball did not have a flat on top I would have more contact. That flat may actually allow or aide in allowing the ball to fully seat into the latch with all the clearance in there.
[image]

When the ball is fully seated up into the top of the coupler the contact patch on the back top rear is approx 3/16". When the ball drops down it moves 1/8" and the contact patch is then approx 1/16"

See here. The ball full up. See 1 11/16"
[image]

Now full down. See 1 13/16"
[image]

Sorry I could not hold the camera, scale, ball and take a pic of front to back movement. It is 1/8" there too when in the center of the dome.

I tried to get a better pic of the contact patch inside. This is the best I can get right now.
[image]

This coupler is not adjustable nor can I take it apart. They welded the lower latch shelf on with the latch pin, latch and spring pre-assembled inside. I cannot change the clearance other then wear it more.

You are looking at the most wear I have, up top where the flat on the top of the ball is. I use grease on the ball all the time. There is no latch wear other then a slight burnish from the ball sliding out. And I cannot find much on the front dome where all the towing is occurring.

I must admit, for only having 3 parts inside plus a spring I never gave this coupler that much though before this post...LOL The coupler has never been a problem once you learn to slide the lock lever back verses trying to pry it up to open to. It won't go up.... Looking around at other TT's, this design is very common. I myself have only seen it on TT's.

Hope this helps explain more. If I could of took the thing apart I would of created an entire to drawing to scale to show.

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: rexlion on 01/30/12 08:20pm

BenK wrote:

rexlion wrote:

In my old Equal-i-zer hitch, the square bars in the L-brackets create an upward force at the ball and downward force at the socket. I agree with Ron and disagree with BenK on that point.

Never disagreed on how a traditional WD Hitch system works

Sorry I missed part of your statement and came to the wrong conclusion. When you wrote, "Whereas a traditional WD system does not
place any WD forces on the ball nor the coupler...other than moves
some of the tongue weight back onto the tongue", my mind did not take note of the part after the "..."

It occurs to me that the side view photo (with all the dashed lines) makes it appear as though the ball fits into a 'side bulge' that is not continued rearward. But the underneath photos don't bear this out (that I can tell). It occurred to me that if a coupler did have sides that bulged out and the area immediately rearward tapered back in, it might prevent the ball from stressing the coupler latch. Not sure what percentage, if any, of these units have such a taper, though.

Mike G.
Liberty is meaningless where the right to utter one's thoughts and opinions has ceased to exist. That, of all rights, is the dread of tyrants. --Frederick Douglass
photo: Yosemite Valley view from Taft Point

Posted By: JBarca on 01/30/12 09:10pm

Ron Gratz wrote:

I fail to see how the tongue jack makes any difference.

Ron, LOL… OK I have stopped laughing hard enough to type now… Thanks I needed that…

I was attempting to see your point of view and review the words I used. I was more referring to the physically movement of the parts. I’ll try again but I do believe we both are now on the same page. This is somewhat a step by step progression of the parts moving when hitching up.

• If the tongue jack is down to the ground when hitching the TT to TV the coupler will only go as low as the jack will allow.

• As the coupler is lowered over the tow ball and you can then latch the coupler, the ball is captured inside and may rest in the coupler in any direction there is clearance to allow it to move in at this point. The jack is still holding the majority of the TW as you stopped lowering it once you can lock the coupler. This is no different on a standard WD hitch or the Anderson at this point.

• As the WD chains are tensioned on the Anderson the truck holding the tow ball and the trailer will draw towards each other. Either TV or TT will rolls towards each other by the amount of clearance in the coupler, the flex of the tongue jack or the clearance in the parking pawl in the TV transmission.

• As tensioning continues the back side of the ball contacts the latch side on the back side of the coupler.

• If there is zero (0) clearance between the tow ball and coupler neither part will move in relation to each other up or down. The tow ball exerts a reaction to the force of the latch pressing on it.

• Depending on the amount of clearance inside the coupler and if internal geometry of the coupler body touched the top of the ball, the tow ball would move in the direction the internal geometry and amount of clearance allowed it to.

• Now to the jack…assuming we have an average truck, 1/2 ton, to 1 ton, at least 750# of TW for sake of discussion, if the jack is supporting the TT “during” the tensioning process it is easier for the truck supporting the ball to move up or down then it would be the TT tongue. The TT has a rigid jack to the ground held down to the ground by the TW, the tow ball held by the truck is supported by springs attached to the axle and can move easier up and down the slight coupler clearance then the TT. If there is no jack then TT tongue “may’ move up on the tow ball if the internal coupler geometry and clearance allowed it to.

OK next point…..

Quote:

As the chain tension increases, the forward thrust of coupler against ball increases. Whether the coupler then moves upward relative to the ball simply depends on the net direction (up or down) of vertical forces generated between coupler and ball. And those forces depend on shapes of the contact surfaces between socket and ball and between latch and ball. I don't think we can unequivocally say that "If the chain forces are high enough they will overcome the down force of the TW and the coupler will cam itself up."

Yes, you are correct. We need to leave the movement up or down out of this as all couplers are not created equal. Good point. I agree… [emoticon]

Quote:

Okay, let's assume the diagram for your specific coupler accurately depicts the relative positions of ball and coupler components with springs tensioned. Then I also assume there must have been a gap between ball and coupler latch before the springs were tensioned. The tensioning of the springs then caused the coupler to move forward and upward (relative to the ball) until the coupler latch was firmly in contact with the ball.

Given these assumptions, I would guess that a relatively small forward thrust, perhaps equal in magnitude to the TW, would cause the coupler to ride up and over the ball to close the gap between ball and coupler latch. The relatively small force requirement would be due to the relatively flat slope of the socket/ball contact surface as you have depicted.

Is your coupler latch adjustable? If so, why should there be a gap between ball and coupler latch prior to spring tensioning? If there is no gap after the coupler is latched, the coupler latch cannot move forward relative to the ball and the coupler cannot rise up relative to the ball.

As I showed to Ben, my coupler has an 1/8” total omnidirectional amount of clearance between ball and coupler. If I held the ball on center of the coupler sphere there would be 1/16” daylight almost all the way around. My coupler is nonadjustable. There could be an up to a 1/8” gap anywhere in the coupler until the chains where tensioned depending on how latch up occurred. Due to my internal coupler geometry the tow ball would wedge itself into the bottom rear portion of the latch. All ball couplers may not do this even while this style coupler is common on many TT’s. As stated the only thing we can say with a high degree of confidence is the ball will be under pressure on the latch side of the coupler.

Quote:

Also, even if what you have depicted for your particular coupler is an accurate representation, I'm sure there are many other coupler configurations which would produce different results. So again, I must believe we cannot be certain that coupler "lift" will occur.

Yes I agree.

Quote:

But, before becoming a completely agreeable person

Ron, that’s OK after a few pages of typing we have usually always ended up agreeing. LOL [emoticon]

Quote:

Thank you for confirming my thoughts.

Quote:

However, although the Andersen hitch is rated for a TW of 1400#, I really doubt that they expect the hitch to generate enough WD torque to restore all the front end load which would be removed by a 1400# TW
Ron

You too…. Yes, I fully agree…. I would like to see scaled axles weights on 1,400# loaded TW TT and heavy truck

John

Posted By: BarneyS on 01/31/12 08:20am

Great post above about the construction of the coupler John! Ron may be the "king of links" but you are without a doubt the "king of detailed picture posts"! [emoticon]

I have the same coupler and, until your post above, have never known what it really looks like inside. Great pictures!!! Thank you for your posts. [emoticon]

Barney

2004 Sunnybrook Titan 30FKS TT
Hensley "Arrow" 1400# hitch (Sold)
Not towing now.
Former tow vehicles were 2016 Ram 2500 CTD, 2002 Ford F250, 7.3 PSD, 1997 Ram 2500 5.9 gas engine

Posted By: BenK on 01/31/12 11:52am

Ah, now that the cross section of your latch is clearer or with more/better
detail...

[image]

Shows that the pawl pivots on it's tail end against a bend back of
the safety plate welded beneath it.

Then the release latch mechanism uses an over center for the pawl
pivoting on it's tail end. Has to be an over center, as if not then
the ball force would lift it if the vector is above the pivot center line.
Otherwise any force from the ball would lift it against the latch
mechanism

Think that is why the latch lever has both a lift and sliding back
motion. Lift it above the over center vector line and then slide back
to get out of the way

So any force from the ball in that direction will have it see the
pawl first and get the brunt of that vector. Some will transfer up
to the latch via that food chain. The moments I can see, but the
length and other geometry would need measurement, but think small
in comparison to the vector against the pawl, then to it's tail
end against the welded safety plate

Then the questions of what is the contact area in order to figure the
PSI. Then the alloy of the steel(s), assuming both safety plate and
pawl are made of the same material alloy and same temper. Good that
the safety plate (my name, what is it called?) has been formed and
should have some work hardening. It is also a catch basin for road
grim/dirt/grit/salts/etc. Wonder how that will do with the added force
of the Andersen Hitch system?

Then the latch food chain and the PSI on the contact points, albeit
small area, small vector

There might be a compounding of vectors with the way the latch mechanism
both lifts and slides. There is a pivot rod just underneath the latch
handle.

Since an over center mechanism, wonder what kinds of shock and vectors
it will take to stay put...or jump out?

That should hopefully be mitigated by the contact between the ball and
top of the glob or as they call it the dome. That seems okay for now
as it requires the ball to drop in order to release, but again, the
latch system was never designed for this kind of dynamic loading
Will have to noodle that some more later

Plus, this is just one type of latch mechanism, wonder how the others
stack up. Think yours works best for the Andersen Hitch, as the others
use a rod/pivot and that leaves questions on how the rod is captured
on both ends, how the pawl interfaces with it, etc, etc

These images are just the ones found with a cross section, Ron's and
assume many more or at least some more designs out there.

[image]

Ron's has more detail but need more on the way the rod is captured
on the pawl. Seems to be just a sheetmetal edge and that then says
all or most of the Andersen Hitch forces are focused there {edit}
Am always forgetting that the top of the ball contacts the dome, so
not all of the forces are onto the pawl/rod, just some if it. More
so if there is tolerance allowing movement of the ball in the captured
condition...but now another new thought...how much in PSI is on that
small dome/ball contact patch?

[image]

Gotta find the one Bryan posted as that one seems best suited for
this Andersen Hitch system

Moderator edit to re-size picture to forum limit of 640px maximum width to avoid scrolling.

* This post was edited 01/31/12 05:46pm by an administrator/moderator *

-Ben Picture of my rig
1996 GMC SLT Suburban 3/4 ton K3500/7.4L/4:1/+150Kmiles orig owner...
1980 Chevy Silverado C10/long bed/"BUILT" 5.7L/3:73/1 ton helper springs/+329Kmiles, bought it from dad...
1998 Mazda B2500 (1/2 ton) pickup, 2nd owner...
Praise Dyno Brake equiped and all have "nose bleed" braking!
Previous trucks/offroaders: 40's Jeep restored in mid 60's / 69 DuneBuggy (approx +1K lb: VW pan/200hpCorvair: eng, cam, dual carb'w velocity stacks'n 18" runners, 4spd transaxle) made myself from ground up / 1970 Toyota FJ40 / 1973 K5 Blazer (2dr Tahoe, 1 ton axles front/rear, +255K miles when sold it)...
Sold the boat (looking for another): Trophy with twin 150's...
51 cylinders in household, what's yours?...

Posted By: JBarca on 01/31/12 06:47pm

BenK wrote:

Ah, now that the cross section of your latch is clearer or with more/better
detail...

Gotta find the one Bryan posted as that one seems best suited for
this Andersen Hitch system

Ben,

Glad you liked the added detail. LOL.... Now I know too...

The coupler Bryan was talking about here

One brand at least is Bulldog, now part of Cequent.

Bull Dog Frame Coupler

I myself have never used them, heard of them and seen them but not in this detail like we are talking about now. Everything I have "heard" is it is a stronger coupler. Not by rating but word of mouth.

Here are the instructions. http://www.bulldogproducts.net/content/downloads/installation/N028499.pdf

John

Posted By: JBarca on 01/31/12 06:50pm

BarneyS wrote:

Great post above about the construction of the coupler John! Ron may be the "king of links" but you are without a doubt the "king of detailed picture posts"! [emoticon]

I have the same coupler and, until your post above, have never known what it really looks like inside. Great pictures!!! Thank you for your posts. [emoticon]

Barney

Gee Thanks Barney. [emoticon]

Glad it helped. I must admit I never looked behind the coupler before either. Never had to. We all learn something from these endeavors.

John

Posted By: BenK on 01/31/12 10:19pm

It's been a revelation for me, as never really thought much about latches.

The total of my latch experience is to spray tons of Amoil HD Metal
Protectorant in there to free them up and to protect them

Knew of the Bulldog, seen them, but likewise never touched nor used one

Of these 5 we have been discussing...yours is 'okay', IMHO, and longevity the key
for me. The other 3 are in question as their pawl is different and think weak for
this application. The Bulldog seems the best suited, but as stated, know next to
nothing about them

Think they all will do, but the big question is for how long and what happens
during an emergency maneuver...

Still think the basic architecture of the Andersen is great, but the
details spoil it for me (that latch and the mounting of the bracket
for the poly bushings)

Posted By: gijoecam on 02/01/12 12:08pm

One thing that hasn't been mentioned in the discussion of the details of the latch pawls is that, in the case of most of the letch assemblies, some portion of those forces are being transmitted through a relatively small pin at some point. In the one BenK has been detailing with the dotted lines, you'll see that any rearward force on the couplet latch is being transmitted through the 'foot' to the bottom part of the coupler assembly as well as the pivot pin on the latch, and the latch locking lever that dogs into the top of the coupler. How robust they are, and what kind of long-term fatigue forces they can withstand remains to be seen.

Also, there was some talk earlier about the rotational moments that the chains or spring bars apply on the trailer. I think that point merits some further discussion as well. With a conventional WDH using spring bars, the springs use the cast hitch head to oppose the force applied to the frame rails. The result is an increase in the vertical force on the ball as the spring bars use the ball as the fulcrum to redistribute the forces. This is perfectly OK to do, in my non-professional opinion, as the hitch ball is being loaded along as though it's a column, and columns can take a LOT of load before failing.

The key difference in the Andersen system is that the chains cause the ball itself to act as the fulcrum. The way it's currently designed will, of course, apply those loads through the coupler's latch. 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. 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.

(I'd love to draw a sketch, but my MS Paint skills suck...)

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