The Equal-i-zer After Some Use - Report

[Inland RV Center, In]

Originally Posted by CrawfordGene

No. Neither is Redwood'. Threads wander around because of lack of intellectual discipline or we are seeking answers from every possible direction. It is the nature of brainwork. I agree overhitching is a vague term and maybe it can be better defined at some point. It is good to be reminded to focus.

Gene

Gene.

Over hitching is usually defined as a hitch bar rating far in excess for the intended job.

As an example, 1200 pound rated bars for a Caravel that has a tongue weight of 350 pounds, towed by a dually or a 3/4 ton truck, or a truck with overload springs.

Maybe one of todays newer words is more apropriate, like "overkill".

Andy

[redwoodguy]

Originally Posted by dznf0g

I think Red said it well in post #93. We've talked about this for a very long time under one subject heading "damage to AS while traveling" Then we continue to talk about overtrucking, overhitching, running gear balance, bad axles, etc. all in the same thread. There are so many dynamic inputs to the rig as it is going down the road that you can't combine all these thing into one coherent answer. I like this thread because it is about drilling down to ONE COMPONENT, analyzing how it works, the physics involved, how the component behaves with a particular input...then another. I think IF and when we gain consensus on understanding how this component applies forces to the AS, we can then more objectively predict what kind of damages are created by misapplication of that component and make better decisions about the component's use.

For example: I believe rivet popping from too much spring bar occurs only during high, slow stress loads during large angle deviations between trailer and TV frames. And I expect those pops to be in the very front of the AS. Perhaps only the center and side lower sections. Perhaps some front pano issues as well. Other pops, I believe to be harmonic vibration and shock load caused....running gear and bad axles respectively. I would expect those to show on the side walls, doors, rearward of the axles etc. All that is for, I assume later, discussions...this one has evolved into strictly a spring bar understanding discussion.

Am I off base?

No sir, you are standing right on the bag! You have have made several important points here about staying on the track of one phenomenon at a time. Isolating the question, drilling down to the narrow answer. It avoids so much confusion that occurs from mixing related, but not causal, factors.

You can see easily how people quickly mix several questions and phenomenon together.

I think the answer to Q1 (ride harshness vs. bar stiffness) can be answered with absolute clarity with one question:

Q: Does the trailer A-frame always move up when the rear TV body moves up, and does the trailer A-frame always move down when the rear TV body moves down?
A: YES, no matter what stiffness of bar is used.

Ergo, the bar stiffness is not controlling or changing the ride harshness or stiffness. It's really that simple. It's true because there is no compliance between the two platforms.

To show an example where that statement would not be true, use an Airsafe hitch. The answer when using an Airsafe would be "no, it does not always move." It might, or it might not, depending on what size unevenness was hitting the TV tire.

I do realize opinions will differ. But, I can't imagine what physical action could be taking place which would cause a "NO" answer to the question above.

On Q2 (stress on frame while traversing gullies and dips) it is easy to model the effect of the bars. You can make the bar so stiff that you will lift the rear wheels of the TV off the ground over the right size gully. At the other extreme you can make the bar so soft it doesn't hinder flex of the coupler-ball at all.

You can picture that with an infinite stiffness on the bar, the entire rig can be suspended between the front axle of the TV and the trailer axle, with the rear TV wheels off the ground. In this maximal condition, can the A-frame withstand this load? Well, maybe not if the TV is massive enough.

This condition would seem to be a serious thing to consider compared to the effects of Q1. My intuition would be that this could cause a wide variety of damages if it was this extreme. The A-frame clearly has some limits to its design strength. You can't pile unlimited load on it. Even with loads in the thousands of pounds range, the members will deflect or bend. Bending the horizontal members of a 28 foot trailer can't be a good thing.

I haven't looked directly at my rig traversing this kind of gully, so this is going to be what I want to see next. I don't think I have ever lifted the rear wheels off the ground, that much I am fairly sure of. Beyond that, I'd like to get a movie of it and study what is happening.

[gmw photos]

Regarding "greasy parts", the Blue Ox hitch is also one of the "clean ones".

[dznf0g]

"I think the answer to Q1 (ride harshness vs. bar stiffness) can be answered with absolute clarity with one question:

Q: Does the trailer A-frame always move up when the rear TV body moves up, and does the trailer A-frame always move down when the rear TV body moves down?
A: YES, no matter what stiffness of bar is used.

Ergo, the bar stiffness is not controlling or changing the ride harshness or stiffness. It's really that simple. It's true because there is no compliance between the two platforms.

To show an example where that statement would not be true, use an Airsafe hitch. The answer when using an Airsafe would be "no, it does not always move." It might, or it might not, depending on what size unevenness was hitting the TV tire.

I do realize opinions will differ. But, I can't imagine what physical action could be taking place which would cause a "NO" answer to the question above."

I can think of one other instance beside an Airsafe hitch. And when it occurs, you think," I hope those chains hold......!"

[slowmover]

Arguing about stiffness and compliance . . sounding like the Sex in an Airstream thread.

Redwoodguy, I may have missed this, but, IMO, it's always worthwhile to work from scale numbers to get an idea of what WDH's are doing, in and of themselves. If this has not been done then problems about "feel" (from steering inputs, etc) always seem a little off-base when anti-sway provisions of the hitch rigging are in play. More complicated questions about suspension interactions aren't helped by uncertainty (being able to replicate the same conditions consistently).

FinalCutJoe has one of the great threads around here on diagnosing hitch performance in one entitled Diminished Hensley Performance. I give it that appellation as the range of potential problems with hitch rigging is huge, larger than we first conceive. And the concerns are not trivial in any respect. While it isn't central to what is being covered in this thread, it may add to the decision tree of understanding how your TV-TT combination feels to you.

With that in mind I recommend a full set of scale weights, empty and loaded, on both your vehicles for your investigatory purposes if not already done (as example, an analysis in a set of posts starting here.)

Hypothetical conjectures, thought experiments, etc, are the pleasure of this -- the good, better, best arguments -- but without numbers we've cut ourselves off from solid ground.

.

[redwoodguy]

Originally Posted by REDNAX

Hypothetical conjectures, thought experiments, etc, are the pleasure of this -- the good, better, best arguments -- but without numbers we've cut ourselves off from solid ground.

Hi Rednax,
You are right. Specific numbers are the only way to compute real answers when specific formulae are a known aspect of the solving the problem. I definitely agree with you.

Ok then. How would we use a set of real scale numbers to answer the question being entertained and dissected here? That question being, "Do 1000# bars on an EQ hitch create a harsher ride at the trailer than 600# bars when all other variables are equal?" I'll follow your lead! I love drilling down to specifics.

[Inland RV Center, In]

Originally Posted by redwoodguy

Hi Rednax,
You are right. Specific numbers are the only way to compute real answers when specific formulae are a known aspect of the solving the problem. I definitely agree with you.

Ok then. How would we use a set of real scale numbers to answer the question being entertained and dissected here? That question being, "Do 1000# bars on an EQ hitch create a harsher ride at the trailer than 600# bars when all other variables are equal?" I'll follow your lead! I love drilling down to specifics.

The numbers, while it may answer some questions, doesn't really matter.

What does matter, is the stiffer the bars, the more shock is transfered to the trailer.

As an example, lets use railroad track for bars. Will they bend? Heck no. Then all of the forces from bumps etc, will be directly transfered to the trailer.

Now lets use broom sticks for bars. Skip the fact they we all know they will easily break. But, since they will easily flex, less forces will be directed to the trailer.

The real ideal situation, is for a hitch manufacturer, for that matter any hitch manufacturer to put up the money for in depth tested.

Folks, in plain english, THAT AIN'T GOING TO HAPPEN !!!

Why a person might ask??

Because they all love things just the way they are.

We invested time and money, to get the ball rolling, hoping that someone, anyone, would resume where we left off. That appears to be a dream that will never happen.

Clearly, however, our tests demstrated the the Equalizer bars, bent the least amount, from a given stress compared to others. That simply means that more round shock will transfer because of that bar stiffness.

There is no need to create any arguements regarding this subject, but there is, we think, a huge need to continue where we left off.

Someone..............anyone ???

Andy

[redwoodguy]

Thanks Rednax for getting me thinking about some real world data analysis. On this question I think it would be an ideal problem for some relatively simple instrumentation and data collection. Again, I am thinking out loud for an approach to this.

Since the question involves ride harshness, the most obvious instrument to apply first would be an accelerometer or tri-axial shock recorder. The latter being rather expensive, but the former might be as cheap as an $2 iPAD app. Ride harshness is exhibited as shocks in the 3-axis of movement. Higher G forces mean harsher ride. When the the rig traverses chuck holes and other road impediments, the harsher ride will generate spikes with higher G-force and or longer periods. It might be quite possible to simply graph a 5 minute ride over some course using first one bar, and then the other. (At the moment I realize that the two bars are not available for the same head, but that's a practical thing to be solved for the test).

I would imagine hard mounting the instrument in the front most part of the trailer. Then making a second pass with it mounted in the rear most part. If a visual analysis (on screen) didn't provide enough resolution, some tedious math could be applied to integrate the data.

I don't know the g-force range of an iPAD/iPhone accelerometer, but if that wouldn't work, there might be relatively inexpensive stand-alone units on offer somewhere. I know you can get a tri-axial recorder of industrial quality for about $800, but that's a bit steep for an experiment like this.

It sure would be cool to do though, wouldn't it? I think it would really put a nice foundation on the whole issue.

EDIT: Well - it looks like there are several apps for the Android. I have a Galaxy Tab, so I will see if I can find a cheap and useful app using the built-in accelerometer. I'm concerned if there is enough dynamic range in such a device, but we'll see!

[redwoodguy]

I just bought the Android app for $1,50 and it looks amazingly useful. 3axis graphing and storage. WOW.

[slowmover]

"Do 1000# bars on an EQ hitch create a harsher ride at the trailer than 600# bars when all other variables are equal?" I'll follow your lead! I love drilling down to specifics.

Measuring Forces at the Hitch

For an A-B-A comparison I'd think that getting the WDH set up according to formula would be first. Each bar set may call for some scale numbers that are different, but the adjustment tweaks ought to be the same each time, as well as being as close as possible.

[redwoodguy]

Ok, it looks like the accelerometer test was done 2 years ago, so I have no need to repeat that idea. The conclusion drawn by that test is precisely what was predicted in the thought experiment in this thread: ride harshness in the trailer is a function of the trailer suspension, not the hitch/TV.

Although his test measured used two different TV subjects, the use of two bar stiffnesses would yield the same conclusion. And that's because the bars do not form a compliance between the two platforms. In fact, there is ZERO compliance of any kind between the platforms in any solid coupled hitch, no matter if the bars are soft or stiff or totally rigid (visualize the compliance of a coil spring between tire and body).

In order to have compliance between two masses, each mass must be able to move independently of the other. The purpose of the compliant part (spring for example) is to store the energy transfer between one mass and the other. No storage of energy = no compliance!

The ball-coupler is solid - - therefore one part can not move without the other moving. Ergo, no compliance exists. If the body of the TV (ball) goes up - no matter how much or how little or how fast or how slow - the coupler will go up also. It must. No other choice is possible. And that will happen exactly so no matter if there are bars, light bars, totally stiff bars, or no bars at all. The function of WD bars is not to be a compliance between trailer and TV. The function is to provide lifting leverage of the TV. A side effect of that leverage is that the hinging of the ball-coupler becomes stiffened against flexing. The illusion here is that the hinging of ball-coupler is a suspension component. It is not.

REDNAX - - yes, I aim to get my rig on the scale as soon as I can find one and do it. Thanks.

[Airtandem]

we have been discussing the stiffness of the bars of the Equilizer hitch and the damage they can cause. after I got the 98, (not foot) home I noticed that the A frame had a slight upward bend and there were cracks in the skin at the corner of both battery boxes not to mention the leaks.
On the A frame were holes where SOB of hitch had been installed.I believe it might been of the bar chain type. If this is true, there should have been sufficient flex to have prevented the cracks and bend in the A frame.
Just some thoughts, and from my experience. Now back to the discussion.
mike

[dznf0g]

Originally Posted by Airtandem

we have been discussing the stiffness of the bars of the Equilizer hitch and the damage they can cause. after I got the 98, (not foot) home I noticed that the A frame had a slight upward bend and there were cracks in the skin at the corner of both battery boxes not to mention the leaks.
On the A frame were holes where SOB of hitch had been installed.I believe it might been of the bar chain type. If this is true, there should have been sufficient flex to have prevented the cracks and bend in the A frame.
Just some thoughts, and from my experience. Now back to the discussion.
mike

Not necessarily, You can also get very heavily rated "chain" type bars as well.

[dznf0g]

OK, so have we (mostly, Andy's not with us, for sure) arrived at some level of concensus that "high frequency, low amplitude" shock loads from the TV are not significant contributors to AS damage? (I still think there may be room for discussion on, for example an empty 3500 dually and a small tongue weight AS vs. a 3500 loaded to cargo capacity....in other words COMPLIANCE of TV and AS suspensions at GIVEN CARGO LOADS.)

NOW, are we ready to move on to "low frequency, High Amplitude" inputs...ie. large angle changes between AS and TV frames. This is where my most concerns are with heavy bars....and where Andy and I are completely on the same page.

[redwoodguy]

Originally Posted by Inland RV Center, In

The numbers, while it may answer some questions, doesn't really matter.

What does matter, is the stiffer the bars, the more shock is transfered to the trailer.

As an example, lets use railroad track for bars. Will they bend? Heck no. Then all of the forces from bumps etc, will be directly transfered to the trailer.

Now lets use broom sticks for bars. Skip the fact they we all know they will easily break. But, since they will easily flex, less forces will be directed to the trailer.


Andy

Andy,
Although it is dangerous to try to interpret what another is saying, I am going to take a stab at it. I think you are describing here a condition of one kind, and assigning it to another. I'd like to try to differentiate the two.

Condition 1
A TV with rock solid stiff suspension that has just about no give at all. The heaviest of heavy duty. When the back end goes over a little bump you get a CLUNK as the tires jump up and down to the pavement. The suspension has virtually "no compliance." No give when you jump up and down on the back. Ok? Let's call this "Hard TV."

Condition 2
A hitch using a stiff WD bar. Let's say the hitch weight is 500# and the WD bars is rated at 1200#. Here the WD bar is clearly a much higher rating than needed for the hitchweight. This bar has essentially no give, no bend when the trailer is attached. But the TV here is just a normal 1/2 T SUV or something with regular suspension. Let's call this "Rigid Bar."

What would I say about these conditions?

1. They mean DIFFERENT things to the trailer.
2. It is easy to see how condition 1 (Hard TV) could cause trailer damage. On a chuck hole, the TV rear end will clunk up and down like a hammer on an anvil. This will be true no matter what kind of WD bar is used. I think this is the case you are really saying causes damage to the trailer. I would agree 100% conceptually. I can visualize the effect very clearly.
3. Condition 2 (Rigid Bar) only seems like it is the same as Hard TV. It actually is not the same, but it appears visually to be the same. This condition is not at all the same as Hard TV. The TV suspension is working fine here, and has plenty of compliance, the bar has no compliance and doesn't even come into play. This is what is being posited by my thought experiment and sketch. The bar only LOOKS like it is a compliant suspension piece, but it is not. It's a deception - the bar is only a lifting member and a resistance to hinging.
4. Take a trip with your AS in Condition 1, then in Condition 2 using a properly balanced WD hitch. I predict the rider inside the AS (I know, I know, but we are just imagining here) will feel a VERY harsh ride in Condition 1, and the ride of Condition 2 will be much softer. In condition 1 when the TV hops over bumps and slams down, so will the A-frame. That's the stress I think you are getting at Andy. But that won't happen in Condition 2 because the TV in Condition 2 has lots of ....dare I say it....compliance! The bar doesn't matter.

I totally respect your 45 years of hands on experience, and I don't want you to think I am challenging your experience. I am not. I am only trying to clarify these questions with the words we all use. Words can create a confusion all their own, as we all know. Please...nobody take any offense here. I intend none.

[redwoodguy]

Originally Posted by dznf0g

NOW, are we ready to move on to "low frequency, High Amplitude" inputs...ie. large angle changes between AS and TV frames. This is where my most concerns are with heavy bars....and where Andy and I are completely on the same page.

ha ha...I feel I am almost ready. But I would like to see if maybe Andy nods with my Condition 1, Condition 2 proposition.

[Inland RV Center, In]

Originally Posted by redwoodguy

ha ha...I feel I am almost ready. But I would like to see if maybe Andy nods with my Condition 1, Condition 2 proposition.

I agree, partially.

But, again, non essential heavy duty bars add to the tow vehicles stiffness.

The less the trailer is forced to comply with a bounce, the more damage it will sustain.

That has gone on for my 45 years experience.

Heavy duty bars are OK, when needed, but they are not needed on a heavy duty tow vehicle suspension.

Andy

[dznf0g]

Originally Posted by redwoodguy

ha ha...I feel I am almost ready. But I would like to see if maybe Andy nods with my Condition 1, Condition 2 proposition.

Nice clarification point. Only thing I would add to your excellent write up. I ASSUME in both 1 and 2 that the hop or bump is of a size and at a speed (elapsed time) which will cause no discernable change in angle for AS and TV frames, relative to one another. This is strictly a situation which we have loosly defined as "shock load"?

[redwoodguy]

Originally Posted by dznf0g

Nice clarification point. Only thing I would add to your excellent write up. I ASSUME in both 1 and 2 that the hop or bump is of a size and at a speed (elapsed time) which will cause no discernable change in angle for AS and TV frames, relative to one another. This is strictly a situation which we have loosly defined as "shock load"?

Yes. That's exactly what I mean. Like chuck holes and tar strips and the like. Instantaneous bumps and shocks. This is the stuff that a coil spring in a car will absorb from the wheel and then release back into the wheel so that the car body doesn't feel it. When you imagine that coil spring working, that is the effect of compliance in the auto suspension. By comparison, the WD bars do no such thing. They do not allow for independent movement of the ball from the coupler, and therefore offer no compliance between those masses.

[dznf0g]

gotcha, agreed.