book that is necessary to truly do it justice...
First must say that modifications are re-engineering. Some so minor to not make
much of a difference. Others can change the thing too much to manifest other areas
that are marginal to become weak links in the food chain (it is a system, not just
anyone component)
Understand that most can not visualize deep and far enough to replicate simulation
Here is a quickie on what a 'good' simulation program will do, or can do...but...
always remember the old axiom..."garbage in, garbage out"
There will be a stress raiser with any pointed set screw/bolt
It will gouge into the tongue member and the point will blunt during the process
The tongue material will work harden.
The paint will become a lube, initially till it is scraped away, but there will
be some left in the mating surface between the tongue material and the set screw/
bolt blunted point. That will then become lube (it is both slippery and compliant
compared to steel) that will allow the set screw/bolt to loosen
Need to know the alloy of the tongue member (and the tolerance of that alloy),
whether hot or CRS, whether there was/is any secondary/tertiary work (not likely)
that would change that spot's temper.
By drilling a pilot (either through, or partial)...question is will
the end mating surface and force be enough to hold in dynamic situations
or did the engineers even consider that when they spelled out these
procedures?
Now to the screw/bolt (back to the tongue in a bit). What is the alloy/grade,
what dia, the pointed end (how sharp, etc), how far from the bracket with the
threads to the tongue member, cut or rolled threads, plated/not, etc
The grade and dia will tell how much torque it is rated for. The program must
be dialed in with the safety margin for that screw/bolt. Assume keeping it in
the elastic range and not into the plastic range (yield)
There is a calculated torque and penetration into the tongue member. The program
will look up in it's tables that tongue member alloy, temper, etc vs the screw/bolt
alloy/grade/dia/torque.
That will be what the designer/engineer wanted in the amount of penetration into
the tongue member. That will also tell how much the point will be blunted and it
that is okay
Not all simulation programs will go so far as to tell the new work hardened level
of both the tongue member and the point of the screw/bolt. Ditto not all CAD
programs will know enough about the paint (lube quality, plasticity, etc after
fully torqued)
Then the program will look at the bracket with the thread that the screw/bolt
used to gouge into the tongue member. This has a bearing on the actual torque
vs the wrench torque. The alloy, temper, etc is important as it is the thread
that, that set screw/bolt bases it penetration into the tongue member...unless
there is a high grade nut or some sort of threaded insert that is hardened pressed
into that bracket. There will be some level of bow and dependent on the thickness
(gauge), width, alloy, temper, etc of that bracket. Also how tight it is to the
tongue member.
Note here that you folks who used wrench extensions may have over torqued the
set screw/bolt. My 1/2" drive socket wrench is about 12" long. I can torque max
about 100 ft/lbs with that thing. A cheater bar that has a 2' length will have
3 times to become 300 ft/lbs as an example. A 1/2" bolt, grade 5 will take about 75 ft/lbs
at some percentage proof. Yield would be around 100 ft/lbs (there abouts, IIRC)
Hope that set screw/bolt is over 1/2" and grade 8 for you folks who used those
cheater bars
That is just in prep for the bushing forces that has a moment (lever arm) from
the point center line of the set screw/bolt to center line of the bushing screw
Back many pages, both John and Ron calculated an approximate force those plastic
bushings imparted. That would then be factored by the above moment to the point
center
This is just a fraction of the 'static' calculations or as I view it in my mind
It gets a bit more complicated when 'dynamic' loading is factored
Hope this gives a glimpse into how a simulation program functions. That the
DB (data base) and programer critical. If the DB does NOT have information on
a pointed setscrew gouging into a steel member...then either they have to go out
and buy an update (if there is one), or write the mini-program to handle that.
Both from a static and dynamic point.
And yes, this is what I see (and more) when I noodle this one, as do
on other designs. If you can't, don't assume everyone can't...
The above is the process and the results of that simulation is a report telling
where there are issues.
Like the gouged mating union and the stresses on the set screw/bolt, tongue
member and the bracket would have an okay or that something was overly stressed
Along with that is the dialed in longevity required, plus some margin.
That is for the static conditions and the real benefit of simulation is for the
dynamic simulation where the computer runs it through the road conditions dialed
in (the road ambient/terrain/etc and the weights, speeds, etc, etc)
![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/biggrin.gif "biggrin")
. . 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
The simulation will take that gouge/dent produced by the set screw/bolt and
run the simulation based on some other attributes
Where it is in reference to the whole member and where between the ball/box, etc
If dead centered the forces are less than if off center. There will be bending
moments on any trailer tongue and there will be tension/compression cycles statically and dynamically.
There would also be some kind or level of 'dent' of 'bowing' in of that member
that would affect the moments of that tongue
Whether it will matter will take some deep DB info and math. I can do that, but
it would take a computer fractions of the time it would take me to look every
thing up and then dig out the calculator
Plus the computer can also compare and simulate it against the whole trailer
I can too, but it would take me orders of magnitude in time to do that.
Anyway, that is what I see when anything like this comes up. Ends up gut feelings
that generally are pretty close or in the general direction of a simulated results
The big 'factor' is the dialed in longevity required. Safety margin to most.
That would be in years and/or 100's of K miles, or some such level dialed in
and there would be a +/- to it.
Yes, I returned my Andersen, but when I took my brackets off it "self" drilled the set screw. The set screw is Pointed, not Flat.
The only thing the brackets did was Tilt, so did my Reese E2 I just put on. Which I also just took back and got an entire new set up with Triangle plates.
Any bracket held on by one bolt on top, and one bolt on bottom is going to move. At least Andersen figured this out and put set screws on it so it wouldn't move.
2012 Kodiak 300BHSL Ultimate with Fall Edition Package
2003 Ford Excursion V10 Sold!!
2005 Ford Excursion 6.0L Diesel
tim and amy wrote:
To Ben and the other engineers. What is the durometer of the urathane that andersen is using? Do you know the specifics? A modeling program without those factors are bogus in my opinion.
To Ben and the other engineers. What is the durometer of the urathane that andersen is using? Do you know the specifics? A modeling program without those factors are bogus in my opinion.
Agree, but don't know the spring rate vs compression (durometer)
Way back towards the early pages there was an exchange between Ron
and John where they calculated the spring force based on the Andersen
manual (number of turns and am guessing they looked at the thread pitch)
That is the static loading, but the dynamic loading can be much, much
higher. Especially during whoopee-dos where the Andersen WD system
sees additional compression of those bushings.
Again, that then has all of those forces on the set screws...and...the
coupler latch...
As for the other, traditional WD systems...their brackets has a different
angle of attack for their spring systems.
Andersen has them longitudinally and the traditional WD's has them
90* (vertical) and the brackets do NOT see anywhere near the longitudinal
forces that the Andersen system sees
Issue with any simulation program is where it has the completeness of DB
and the parameters (both static and dynamic) dialed in right.
-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?...
tim and amy wrote:
To Ben and the other engineers. What is the durometer of the urathane that andersen is using? Do you know the specifics? A modeling program without those factors are bogus in my opinion.
Durometer is a measure of a material's "hardness" -- IOW, a measure of resistance to permanent deformation. As you probably are aware, urethanes have a wide range of hardness values.To Ben and the other engineers. What is the durometer of the urathane that andersen is using? Do you know the specifics? A modeling program without those factors are bogus in my opinion.
Durometer is not the same as the stress-strain relationship (a.k.a. "spring rate").
I attempted to address the spring rate question back on page 24 in this post.
Ron
2012 FR Surveyor Sport 295
2015 Nissan NVP 3500 SL 5.6L
Tekonsha P3 / "New" Blue Ox Sway Pro
It really depends on how much compression you need of the urathane bushing. What I found on mine, was if I was at 6 threads showing, then yes, it would do as shown in the video. But if over 6, then no, I had to back off the nuts. Really between my now new Reese system and this, the set up time is no different in my case.