1000# vs. 1400# bars?

[dznf0g]

Originally Posted by uncle_bob

Hi

You stated:

"If one has downward head tilt, then there is definitely an interaction between WD and sway control. No head tilt, no interaction....or maybe influence is a better word"

That is not correct.

The Hensley and Propride folks both calm to be "emulating" a 5th wheel via their mechanical magic. The 5th wheel is said to have total immunity to sway. It's all geometry in the horizontal plane. Vertical plane does not get into it.

This is talking about sway ( oscillation that puts you in the ditch) and not about porpoising (which is a completely different thing).

Bob

I don't think we are on the same page. I wasn't talking about PPP exclusively, only that when even maximum head tilt is in place, the spring bars are pretty much parallel to the ground. In that situation, there is little interaction between the WD tension and sway control.

With conventional hitches, there is some friction (not a lot really) which creates an interaction, but if there is a lot of head tilt, there is quite a bit of interaction on turns.

Some, like Reese dual cam, rides in a saddle and has a pretty decent on-center "lock position", IF the cam arm is adjusted for the load and the spring saddle rides perfectly centered on the cam. The more WD the better this on center lock is.

I wasn't talking about PPP at all as it relates to a fifth wheel.

[Hermes]

Originally Posted by jcanavera

One other thing to consider is dips in the road. If you have ever been driving and hit a dip in which the tow vehicle dips up and down, the forces applied will cause the trailer nose to dip which increases the forces being applied to the lift bars. As noted by others if you don't positively know the weight of the trailer, too light a bar may not be able to support the weight being applied as the nose pitches down. There have been cases of bars cracking or snapping.

I've hit some pretty bad dips (one for sure on I-94 in Indiana) that would raise you out of the drivers seat if you aren't belted in. With my hitch weight on my 30' slide out at over 1260 lbs, I'm happy to have the reserve in 1,400 lb bars to resist the downward forces applied by dips in the pavement.

Jack

I would be less concerned with the bars snapping or cracking and more concerned with the pressure placed on the bars and the Airstream frame by the raising of the front axel above the rear axel, leveraging the length of the truck from the front axel to the hitch head.

Mind you the AS model with a slide out may have a stronger/stiffer frame. I have compared the rivet density on Excella models with current models and there were definitely more rivets in the earlier models than you have today, which may explain the resilience of older models to frame stress and front end separation. With my new 1000# round tapered flexible bars, there is a bit more up-down movement than I had with the square stiff 1200# bars when driving on uneven roads, but there is also a lot less stress on the trailer front end. So I shouldn't be getting any more front end separation issues.

[dznf0g]

Just as an aside from regular programming. Back in 2011, I had asked the Mothership for any pics of my 30' Classic NON-slide. They only had 2 pics of a 30' Slide Classic, but said they were exactly the same EXCEPT for the extra bracing in and around the slide itself. You can see that in the pic(s). Frame rails and A-frame are the same as a non-slide.

[uncle_bob]

Originally Posted by dznf0g

I don't think we are on the same page. I wasn't talking about PPP exclusively, only that when even maximum head tilt is in place, the spring bars are pretty much parallel to the ground. In that situation, there is little interaction between the WD tension and sway control.

With conventional hitches, there is some friction (not a lot really) which creates an interaction, but if there is a lot of head tilt, there is quite a bit of interaction on turns.

Some, like Reese dual cam, rides in a saddle and has a pretty decent on-center "lock position", IF the cam arm is adjusted for the load and the spring saddle rides perfectly centered on the cam. The more WD the better this on center lock is.

I wasn't talking about PPP at all as it relates to a fifth wheel.

Hi

What I said was that not all hitches have interaction between WD and AS.

What you came back with was:

"If one has downward head tilt, then there is definitely an interaction between WD and sway control. No head tilt, no interaction....or maybe influence is a better word"

The term used in your statement is "definitely". My point is (and has been) that there are hitch designs that do not have this interaction.

Bob

[Spaggs]

Sean Woodruff advised me that it was OK to give dznf0g his email address so they could talk Engineer to Engineer.
Personally, I would like a dummied down version of their conversation so I can understand why Sean believes that that the 1400# bars will not put excess stress on the Airstream. I mentioned “popped” rivets to him and this was his response:

“Stiffness is directly proportional to the force applied. Stiffness is equal to the force divided by the deflection of the bar.

With a 3P hitch you control the force applied to adjust the stiffness of your bars through the jacks.

You can run them as stiff as you’d like regardless of the rating on the bar.”

I understand some of this, but mostly, NOT! The again, it took me five (5) years to finish high school.

Sean told me that he has tried to talk to Airstream Engineers, but they would never contact him back. Really!? Airstream doesn’t want to talk to ProPride. It seems to me like a great opportunity to combine intel between the two and be able to promote each other.

If I were Sean, I’d fly to Jackson Center. If I were Airsream, I’d fly to Holly, MI. But what do I know.

[dznf0g]

Originally Posted by Spaggs

Sean Woodruff advised me that it was OK to give dznf0g his email address so they could talk Engineer to Engineer.

Personally, I would like a dummied down version of their conversation so I can understand why Sean believes that that the 1400# bars will not put excess stress on the Airstream. I mentioned “popped” rivets to him and this was his response:



“Stiffness is directly proportional to the force applied. Stiffness is equal to the force divided by the deflection of the bar.



With a 3P hitch you control the force applied to adjust the stiffness of your bars through the jacks.



You can run them as stiff as you’d like regardless of the rating on the bar.”



I understand some of this, but mostly, NOT! The again, it took me five (5) years to finish high school.



Sean told me that he has tried to talk to Airstream Engineers, but they would never contact him back. Really!? Airstream doesn’t want to talk to ProPride. It seems to me like a great opportunity to combine intel between the two and be able to promote each other.



If I were Sean, I’d fly to Jackson Center. If I were Airsream, I’d fly to Holly, MI. But what do I know.

To be clear, I am not an engineer. My degrees and career were in applied technology with an OEM auto maker. I interacted with engineers relative to problem root cause identification and remedy.

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[dznf0g]

Originally Posted by uncle_bob

Hi



What I said was that not all hitches have interaction between WD and AS.



What you came back with was:



"If one has downward head tilt, then there is definitely an interaction between WD and sway control. No head tilt, no interaction....or maybe influence is a better word"



The term used in your statement is "definitely". My point is (and has been) that there are hitch designs that do not have this interaction.



Bob

And I stand by that. If the trunnions or front curved part of the bars are not perpendicular to the ground (rearward tilt), they swing in a vertical arc on turns, thus the interaction of changing (primarily directionally) wd and some (little) change in sway control by tensions and resulting friction.

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[Spaggs]

Originally Posted by dznf0g

And I stand by that. If the trunnions or front curved part of the bars are not perpendicular to the ground (rearward tilt), they swing in a vertical arc on turns, thus the interaction of changing (primarily directionally) wd and some (little) change in sway control by tensions and resulting friction.

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So, in layman’s terms, this translates into undue stress to the Airstream frame?

Please let us know what you find out from Sean. I, personally, would like to know his thinking regarding this stress and why he does not believe his 1400# bars will result in “popped” rivets.

[uncle_bob]

Originally Posted by Spaggs

So, in layman’s terms, this translates into undue stress to the Airstream frame?

Please let us know what you find out from Sean. I, personally, would like to know his thinking regarding this stress and why he does not believe his 1400# bars will result in “popped” rivets.

Hi

First off, stress on the frame is something that happens in the vertical axis ( up and down). Sway is the trailer wagging back and forth in the horizontal axis (right to left). One is not the same as the other.

WD is what puts stress on the tongue of the trailer. To much WD is not going to do the trailer any good. With any spring, the amount of WD is a combination of the spring and the adjustment. You can adjust a light spring to do the same level of WD as a heavier spring. Until you run out of range on the adjustment ( chain, crank, whatever) they are doing the same thing.

The only reason to fret about spring size is to keep from running out of range on
the adjustments.

Real simple:

If I have a "thousand pound spring" and I deflect it 1", I get 1,000 pounds of force. If I have a "two thousand pound spring" and I deflect it 1" I get 2,000 points of force. Deflect either one half that distance and you get half the force. That's why you have adjustments.

Bob

[Mikemdd]

Originally Posted by uncle_bob

Hi

First off, stress on the frame is something that happens in the vertical axis ( up and down). Sway is the trailer wagging back and forth in the horizontal axis (right to left). One is not the same as the other.

WD is what puts stress on the tongue of the trailer. To much WD is not going to do the trailer any good. With any spring, the amount of WD is a combination of the spring and the adjustment. You can adjust a light spring to do the same level of WD as a heavier spring. Until you run out of range on the adjustment ( chain, crank, whatever) they are doing the same thing.

The only reason to fret about spring size is to keep from running out of range on
the adjustments.

Real simple:

If I have a "thousand pound spring" and I deflect it 1", I get 1,000 pounds of force. If I have a "two thousand pound spring" and I deflect it 1" I get 2,000 points of force. Deflect either one half that distance and you get half the force. That's why you have adjustments.

Bob

Is this scenario correct:

1500# bar deflected 1/2 inch = 1000# force (just as example)
1000# bar deflected 1 inch = 1000# force (just as example)

If you go over a big dip, both bars temporarily deflect an additional 1/2 inch:

Now 1500# bar has an additional 1000# force for a total of 2000# (assumes deflection is linear)
Now 1000# bar has an additional 500# force for a total of 1500#

If correct, this would be the reason for the smaller bars in most cases.

[uncle_bob]

Originally Posted by Mikemdd

Is this scenario correct:

1500# bar deflected 1/2 inch = 1000# force (just as example)
1000# bar deflected 1 inch = 1000# force (just as example)

If you go over a big dip, both bars temporarily deflect an additional 1/2 inch:

Now 1500# bar has an additional 1000# force for a total of 2000# (assumes deflection is linear)
Now 1000# bar has an additional 500# force for a total of 1500#

If correct, this would be the reason for the smaller bars in most cases.

Hi

If you watch how these things work, there is a bit of a pivot process involved as well. It's not quite as simple as that example. No matter what the springs, big dips will be "fun". That's why they all tell you to disconnect the springs before you pull into the campground or do other fancy maneuvers.

If the springs are near max, the pivot process is impaired. You then get something crazy happening with the "soft" springs. How much pivot is involved depends a *lot* on which hitch you have.

Is the 1000 pounds at 1" or at 12" or 24" .... they don't seem to ever talk about that side of it. One probably needs to know that to redesign the system on the fly.

Lots of variables.

Bob

[Spaggs]

Contacted Pro-Pride and spoke with Brent. He advised that Airstream has recognized that their 1400 bars are not responsible for popped rivets at the front of the trailer. Brent couldn’t put his finger on the source for this info. Would be interested in reading the text pertaining to this statement.
When I talked, via email, to Sean Woodruff, he said that the stiffer bars are not the reason for popped rivets. As a matter of fact, he was adamant about the subject, but provided no factual content.
Anyway, Brent is sending me the 1000 lb. bars and will fully refund the cost of the 1400s. All I’m paying for is shipping. Due to the price difference between the two bars, I’ll break even, sort of.
Hope the smaller bars is the right choice.

[OrangeCrush]

Originally Posted by Spaggs

Contacted Pro-Pride and spoke with Brent. He advised that Airstream has recognized that their 1400 bars are not responsible for popped rivets at the front of the trailer. Brent couldn’t put his finger on the source for this info. Would be interested in reading the text pertaining to this statement.
When I talked, via email, to Sean Woodruff, he said that the stiffer bars are not the reason for popped rivets. As a matter of fact, he was adamant about the subject, but provided no factual content.
Anyway, Brent is sending me the 1000 lb. bars and will fully refund the cost of the 1400s. All I’m paying for is shipping. Due to the price difference between the two bars, I’ll break even, sort of.
Hope the smaller bars is the right choice.

After receiving this information from ProPride, what what made you choose to go ahead and switch to the 1000lb bars?

[Spaggs]

Originally Posted by OrangeCrush

After receiving this information from ProPride, what what made you choose to go ahead and switch to the 1000lb bars?

Have you read the previous posts? Most everybody has told me that the 1400 lb bars are too stiff. That this puts too much stress on the front of the AS with possible popped rivets.
I think that my tongue weight will be ok since I plan on putting two (2) adjustable 60 lb dumbbells under the bed with a thicker/heavier mattress. I can throw my tool box and tire inflator back there, as well.
If the range of the bar effectiveness is, let’s say, 200 lbs each way, I’ll be closer to the pivot point with the 1000 pounders than the 1400s.
If you have the 1400s with a similar length AS and pull it with a F350/3500, or equivalent, and have no problems, then I will keep the 1400s and return the 1000s.

[OrangeCrush]

Originally Posted by Spaggs

Have you read the previous posts? Most everybody has told me that the 1400 lb bars are too stiff. That this puts too much stress on the front of the AS with possible popped rivets.
I think that my tongue weight will be ok since I plan on putting two (2) adjustable 60 lb dumbbells under the bed with a thicker/heavier mattress. I can throw my tool box and tire inflator back there, as well.
If the range of the bar effectiveness is, let’s say, 200 lbs each way, I’ll be closer to the pivot point with the 1000 pounders than the 1400s.
If you have the 1400s with a similar length AS and pull it with a F350/3500, or equivalent, and have no problems, then I will keep the 1400s and return the 1000s.

Spaggs, yes I have read all the posts. I have been following your thread because I have a new PP3 hitch with 1400lb bars and F250 that I have not setup yet and wanted to hear Sean's response. I did not mean for my question to come across wrong.

The popped rivet frame stress thing is very complicated. I have nothing but praise for dznf0g's analysis, however, it is a static analysis. The problem with popped rivets can only be determined through a dynamic analysis/model validated with testing and instrumentation. I am not going to pretend to know the answer but nothing I have seen definitively says popped rivets are caused by frame flex due to a 1400lb spring arm that was was properly dialed in. How do we know it is not due to bouncing or porpoising causing high G forces on the body where it contacts the frame. How do we know Airstream did not simply have some assembly issues on some units and once fixed they were fine. There is some lore on the forum that says a stiffer TV suspension should be matched with a lighter WD spring arm. A RivetMaster several years ago on this forum stated it was "simple physics" with no hint of actual knowledge of physics to support this claim. I just found out this morning that a friend of a friend who was looking at buying an Airstream decided to buy a Casita instead because someone told them that Airstreams can not handle the Colorado climate which will cause them to pop rivets. It's kinda funny, but if you use the search engine and go back 6-8 years switching from 1000lb bars to 1400lb bars was all the rage at the time. I too have talked to Brent about this a few times and based on Airstream and Seans response I am going to stick with the 1400lb bars when I set things up in the next few weeks. My configuration is a 2017 25FB with 2022 F250 and I will come back and let everyone know if I start seeing some popped rivets.

[Powerrunner]

I have the Hensley with the 1400# bars a F250 with 5 leaf springs pulling a 30’ 2019 International. We did around 15,000 miles last year with no popped rivets. I am happy.

[dznf0g]

I never personally claimed popped rivets are caused by hitch spring bars. I believe popped rivets are caused by out-of-balanced harmonics.
My concern with to high rated bars is tongue flex and the stresses on the front wall....which could cause some rivet issues in the front wall, due to buckling.

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[s1000pre]

I still question the 1,400lb bars on my Hensley. I pull my 2021 FC30 bunk with an f150 and 1,400lb bars. My front storage opens fine without weight distribution. As soon as I add in weight distribution, the compartment door becomes really tight. If you can add in enough WD with 1,000lb bars, that’s the direction I would go.

[Spaggs]

Originally Posted by s1000pre

I still question the 1,400lb bars on my Hensley. I pull my 2021 FC30 bunk with an f150 and 1,400lb bars. My front storage opens fine without weight distribution. As soon as I add in weight distribution, the compartment door becomes really tight. If you can add in enough WD with 1,000lb bars, that’s the direction I would go.

Reminds me of living in Rochester, NY when we had an ice storm in the early 90s. My neighbor’s tree limb (huge Box-Elder) slowly sank onto my garage roof causing my garage door to stick and not open. Once the limb was removed, I could open the door again.
I’ve had the1400s for about two years, now. I think I’ll hold on to them for a couple of weeks and start off with the 1000s and if they are not working for me, I’ll try the 1400s and chalk it up to R&D.
Thanks for everyone’s input. This forum consists of the most intelligent and courteous group I’ve had the pleasure of dealing with.

[OrangeCrush]

Originally Posted by s1000pre

I still question the 1,400lb bars on my Hensley. I pull my 2021 FC30 bunk with an f150 and 1,400lb bars. My front storage opens fine without weight distribution. As soon as I add in weight distribution, the compartment door becomes really tight. If you can add in enough WD with 1,000lb bars, that’s the direction I would go.

If both bars are within range for proper weight distribution, then when properly setup they will apply the same amount of force therefor you will notice no difference relative to the tight door you mention. On the road they will act different.