Campin LI 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.
BenK wrote:
![[image]](http://img.photobucket.com/albums/v77/bentoy/Towing/AndersonWDhitchvectordiag1.jpg)
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.
Correct in the beginning sequence, but to complete that vector...as
the chain is tensioned it will pull from both ends.
The end on the tongue clamp is stationary, so it will pull the tongue towards the
ball shank plate.
Since the ball shank plate is connected to the ball shank, it will 'try' to come
towards the stationary clamp on the tongue.
That will then have the tongue move towards the ball
It will then bump into the ball and since the ball is inside the coupler. It will
contact the latch side of the coupler interior to complete this vector system
That then will have the ball shank 'try' to go off perpendicular. Since the ball
shank is captured inside the special shank with the tapered hole lined with
friction material...it will tilt the ball shank, which will tilt the shank,
which will impart a lifting moment on the receiver pin box, which will then
place that moment on the TV frame and distribute weight from the TV's rear
towards the TV's front.
The diagram is the end result and simplified as was lazy and didn't want to spend
the time to draw each moment and the resultant vectors
Then the other potential issues or weaknesses to this architecture
Whether the tongue rail clamps will hold. That is a LOT of force and
to use just frictional clamp is risky over time
The coupler latch taking the brunt of the forces on SOME of the coupler
designs. As some do NOT have the dome contact the ball in the rearward
direction of the ball
Let me add a few things to maybe help. In the world of force analysis the terms "force" and "reaction" are used. The directions of both are exactly opposite each other. Reaction of Force
Unless one is "into" this type of analysis it can get confusing which way is which. Many people can understand the force direction as they can see it or relate to it.
For example a simple cloths line. The cloths hanging on the line creates tension in the rope and the tension or "force" is pulling on the hook screwed into the side of the house or pole. Most can relate to the "force" in the rope as they can see it or have experienced it. The hook in the wall has a "reaction" (or a reacting force) which is resisting being yanked out by the "force" of the cloths pulling on the rope. If the wood around the screw of the hook cannot resist the force, the wood rips out because the reaction force at the hook was greater then the wood could handle.
Trying to explain to someone by arrows on a screen can be confusing if you do not know if they are talking about the force or the reaction. Especially if they did not declare which was which. Or if you are not into doing this by mathematical or graphical expression it can be hard to understand. OK enough of this....
Let's try this. See this picture
![[image]](http://i23.photobucket.com/albums/b378/JBarca/Hitch%20Setup/Anderson/Stdhookup1.jpg)
In order for WD to occur on the TV, the WD hitch has to create a rotational force (or torque) in the TV receiver cross tube. You can see the CW arrow there. At this point it does not matter which brand WD hitch you have that same torque needs to occur to create WD.
WD on any hitch (that I can think of) requires the use of levers to create mechanical advantage. The longer the lever the higher the mechanical advantage and the less force it takes pulling on the lever.
For simplicity sake lets look at the traditional WD hitch like in the picture above. The trunnion WD bar is 28.5" long from the tow ball center to the snap up chain. That 28.5" is a lever. It can be thought of a 28.5 to 1 mechanical advantage so to speak. So far so good?
Now lets look at the Anderson WD hitch
Here we are with the chains slack
![[image]](http://i23.photobucket.com/albums/b378/JBarca/Hitch%20Setup/Anderson/Hookup1.jpg)
And now we start to crank the nut behind the urethane spring which creates tension in the chain.
![[image]](http://i23.photobucket.com/albums/b378/JBarca/Hitch%20Setup/Anderson/Hookup2.jpg)
WD on the TV still works the same in the receiver. We still have to create the same torque in the receiver in order to apply WD on the TV to the same axle weights. Since the tongue weight has not changed on the TT because of hitch brand we still need to create the same amount of torque in the receiver to transfer weight off the rear axle of the truck, some to the front axle some to the TT axles.
Now how does the Andersen hitch create this torque?
The tow ball is estimated to be 8" long from the ball center to the chain attachment point. I created this estimate by looking at the relationship from pic's of the 6" wide A frame. It "might" be an inch or so longer and the longer the better.
If you pull hard enough towards the TT on that 8" long tow ball shank it will start to create a rotary force (torque) in the hitch shank and the TV receiver. In the case of the Andersen this would be a 8 to 1 mechanical advantage.
Up above on my Reese hitch I have 28.5 to 1 and on the Andersen we have 8 to 1. Looking at the difference in the 2 mechanical advantages 28.5 / 8 = 3.6 times difference. OR that it will take 3.6 times more force to pull on the 8" long tow ball shank then on the Reese to create the same torque as measured at the tow ball.
Now putting some numbers to this.
If on the Reese it took 1,000# of force pulling on the chain at the end of the WD bar (the snap up area) that would be 28.5" x 1,000# = 28,500 in. lb (2,375 ft lb.)of torque in the hitch shank at the tow ball area.
Since we created 28,500 in. lb of torque at the tow ball area to do the job of WD by the Reese hitch, the Andersen has to create this same torque to do the same WD at the tow ball area.
Since the lever length is only 8" long in place of 28.5" long we have to pull harder. 28,500 in. lb / 8" = 3,563 # of force is needed in the Andersen WD chains to create the same equivalent WD on the TV.
This example was only one side of the hitch. Both sides in the conventional WD hitch and the Andersen create equal forces in the chains when the TV is straight ahead.
A concern of mine on the Andersen now realizing how high the forces for WD need to be is, the frame brackets that attach the urethane springs to the frame. They need to be strong enough attached to not slide down the frame. They do have a set screw to bite into the frame rails. On tube frame you can bite in on the inside and outside. On C channel you can only bite in on the outside. In the hitch instructions it is stated.
"A good option to strengthen and secure the hold of the set screws is to pre-drill a 7/16" (11mm) hole into the frame where
the set screws will be located."
They do not declare when to drill just it is a good option. Odds are high they where wanting to create a no drill method of attachment. The reality is this area has to be positive and no slip. I will give them credit as they at least mentioned it. On my Reese if the TW approaches 1,200# Reese allows you to bolt the snap up to the frame. As the snap up can spring open in a turn under certain conditions. The only way you find this out is calling tech service and asking or talking about a sprung open snap up. Then they tell you it is OK to bolt the snap up's on.
![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/doh.gif "doh")
Andersen made a good effort at creating a large clamp force to hold the spring brackets to the frame. They are using 5/8 bolts torqued to 150 ft. lb. to create the squeeze and a set screw to create more positive attachment. On my big 6" channel frame it can take the squeeze, however the 1 size fits all may not apply on all TT's. I would be cautious of this high squeeze on thin wall tube A frames of ultra light TT's. Tube crush can and has occurred while even tightening up snap up brackets on the conventional WD hitch.
With the differences in force needed to accomplish WD on the truck, the Andersen will have to work harder at it, 3.6 times higher then the conventional WD hitch. In theory it can do it. In practice if it can obtain it and sustain it is yet to be proven.
If I have confused you even more.... let me know. I'll try and break it down simpler if needed.
Hope this helps
John
PS. For purposes of this example I did not include the distance from the center of the tow ball to the center of the receiver torque tube in the mechanical advantage comparisons. The shorter the shank the less mechanical advantage you have on either brand hitch.
Moderator edit to re-size picture to forum limit of 640px maximum width to avoid scrolling..
* This post was last edited 02/09/12 07:39pm by JBarca *
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!)
that would reduce the ground clearance when the bottom plate goes down.
Stuck with the height of the coupler vs levelness of the trailer, that is not
changeable unless the coupler is changed out
By going to a longer shank, the WD moment (lever arm) is increased
With the Andersen WD Hitch system, there is NO un-weighting and over-weighting
in whop-d-doos/etc. The coupler and ball take that as just a pivoting motion
and the spring rates remain constant, as I see it now...have to noodle that some
more later...just finished my big pot of chili, got the sausages ready for the
grill, made the corn bread, cold pizza from last nite, etc in ready for the big
game...
Torn...rooting for the home town boy (Brady) or my Niner's league...
BenK wrote:
With the Andersen WD Hitch system, there is NO un-weighting and over-weighting in whop-d-doos/etc. The coupler and ball take that as just a pivoting motion and the spring rates remain constant, as I see it now...have to noodle that some more later...
With the Andersen WD Hitch system, there is NO un-weighting and over-weighting in whop-d-doos/etc. The coupler and ball take that as just a pivoting motion and the spring rates remain constant, as I see it now...have to noodle that some more later...
Ben are you sure? Think about it.
If the front of the truck changes elevation or the entire truck changes elevation in relation to the TT still being on level ground, the hitch shank in the truck receiver is going to change angles in relation to the TT frame. If the hitch shank changes angles to the way it was tensioned when the rig was level the WD chain forces will change along with it.
Think of the high up nasty RR crossing as an example. TT wheels down on the level and TT frame level with the road. The truck now starts going up hill at a 30 to sometimes 45 degree angle to get over the tracks. (At least hear in outbacks of Ohio that is.) During that transition the hitch shank attached to the truck is going to change angles in relation to the TT frame. It will back flex on the way up and unflex going over the top to again back flex on the way back down. When the to ball shank changes angles in relation to the TT frame rails, the WD chains will change tension.
And I "think" the Andersen will be worse then the traditional WD hitch. If the mechanical advantage of the Andersen is 3.6 times less then the traditional WD hitch then the change in angle at the hitch head will affect the Andersen more to totally unload 3.6 times faster. The spring rates constants are greatly different. I'll have to think more on this but my gut tells me both will generate a higher WD load when the TV goes up the ramp and then totally unloads going over the top to once again go way up in force coming back down over a nasty RR crossing. To figure this out one has to do a spring rate change verses the angle of hitch head change and tow ball shank change to see who is worse per degree of shank angle change.
OK did I mix that up or not?
John
No difference and realized didn't take enough time to noodle it thoroughly enough
Know why I got a bit confused...the direction of the spring orientation is 90*
and only saw how a whop-d-do affected 'just the spring'. It affects the whole
the same for both architectures
Question: "If you were spending 40K on a new trailer, would you be comfortable using this hitch"?
Answer: "I wouldn't use any other hitch".
Question: Do you need to tighten / loosen the two nuts for hitch / unhitch?
Answer: Yes. First time you hitch, tighten the nuts to compress the bushing 1/4 inch. Then count the number of threads (same as counting chain links with other types of hitches) sticking out of the nut. Subsequent hitching up, you tighten to that thread position. No torque wrench needed. I mentioned marking the threads with paint or nail polish, he said "good idea, once you get it set for your trailer".
Question: Unhitch procedure?
Answer: Pretty much same as other types of hitches, tongue jack down to take off weight, loosen the nuts, and pull the pin to release the plate. No heavy bars to remove, no heavy hitch to remove, this entire set up ways about 60 lbs.
Question: How often is it necessary to replace friction material inside ball mount?
Answer: It's got a lifetime garantee, you shouldn't need to replace that.
I was told this hitch was in R&D for five years and only started marketing in August 2011. They did not want to compete with Reese and Equalizer, with a product that was similar to Reese / Equalizer design. Thus, a totally new hitch concept.
The guy was pretty convincing.
18 Nissan Titan XD
12 Flagstaff 831FKBSS
Wife and I
Retired Navy Master Chief (retired since 1995)
them about the coupler latch and if they would warranty that?
Noodling some more after that last cycle brought up the whop-d-do situation
Wonder how much travel the plastic springs have. Distance in compression and extension
Will it go to zero and over the preset tension? Yes, but how much? and then vs
the traditional WD setup in the same whop-d-do?
That then brings up adjustments and then how much height variation does the
Andersen system have. No head tilt. No raising of another ball. Kinda sorta okay
but that is if the tongue vs the holes in the shank line up. What if they don't
and that is where the head tilt comes in.
What will an off height do to the tensioning of the system? Then what during a
dynamic whop-d-do?
I keep pondering those chains though. All that stress and one "weakest link" would shoot through three cars before coming to a rest. I don't think the spring bars would do that much damage as they would be heading for the earth if they snapped.
The biggest drawback for me is the placement of the shock mount at the end of the chain. I have but two places I can place the mount and if they aren't at the right position at the end of the manufactured length or after taking out a link or two I'd be paying for the return shipping. I don't want to go through that.
I've posed the question in an email to their customer support but haven't heard back after three days. Anyone know the distance from ball center to retainer placement? I've looked but cannot find where they give any measurements.
2015 Tiffin Allegro Open Road 36LA
To Infinity, and Beyond! - Our Campsites (Bing Maps)
of those plastic springs during a whop-d-do
Will they continue to compress? Up to how much to then become a solid
Will the clamping method hold or will it then slide along the tongue member?
Here is what can happen when stored energy, in this case the nylon tow strap,
lets loose all of that energy and is what Bob is talking about
![[image]](http://img.photobucket.com/albums/v77/bentoy/Towing/JeepCJtowstrapthruwindow.jpg)
BenK wrote:
Bob, now that you mention this...also wonder about the travel distance capacity
of those plastic springs during a whop-d-do
Will they continue to compress? Up to how much to then become a solid
Will the clamping method hold or will it then slide along the tongue member?
Here is what can happen when stored energy, in this case the nylon tow strap,
lets loose all of that energy and is what Bob is talking about
Bob, now that you mention this...also wonder about the travel distance capacity
of those plastic springs during a whop-d-do
Will they continue to compress? Up to how much to then become a solid
Will the clamping method hold or will it then slide along the tongue member?
Here is what can happen when stored energy, in this case the nylon tow strap,
lets loose all of that energy and is what Bob is talking about
Poor analogy... Straps can stretch and store a tremendous amount of energy. When the anchor point fails (like a shackle), the strap acts like a rubber band, sling-shotting the pieces like you see in that photo. I've witnessed such failures with my own four eyes. I've not seen anyone killed, but it's only by dumb luck.
The chains on the Andersen WDH, on the other hand, pose much less of a threat. Chains in general do not stretch much or store much energy before snapping. In the event they do snap, those chains are not very long and both ends are captured, so it's not like it's going to launch bits and pieces a thousand feet. The chain is under tension, with one end pointing up under the tow vehicle and the other directed at the front of the trailer (more or less). Furthermore, they are relatively short (less than 36" overall?) so even if the end detaches, it's not going far.
In terms of the travel of the bushing, lets assume, for a second, that the ball changes angle from one extreme to the other of approximately 30 degrees between maximum incline and maximum decline, or in other words, 15 degrees nose-up to 15 degrees nose-down on the tow vehicle. (I strongly suspect that anything more than that will have parts of truck or trailer dragging the road) If we assume that the distance from the pivot point (on the ball) to the chain attachment point is 8 inches, a simple approximation is going to be 8sin(30) which equals 4 inches of total travel, or plus or minus 2 inches from the static point on level ground. In reality, I strongly suspect the maximum change in angle you're going to see between the tow vehicle and trailer on a steep driveway approach is not much more than 5 or 6 degrees, which makes for a rough travel of roughly 1.387 inches... That's not all that much movement, and I would expect that the bushings would be able to easily absorb that motion without a problem.