Forum Discussion

mkirsch's avatar
mkirsch
Nomad II
Jan 19, 2016

Controlling Sway Stresses Trailer Frame?

Let's say I have a travel trailer with a BAD sway problem. Rather than fix the problem, I decide to "fix" the problem with a Propride or Hensley.

Even though the trailer is now "fine," underneath all that it is still TRYING to sway. The Hensley/Propride is stopping the trailer from getting out of control, but the trailer is still slamming side-to-side against the sway control.

How long before something breaks?

22 Replies

  • Huntindog's avatar
    Huntindog
    Explorer
    Feb 12, 2016
    alexleblanc wrote:
    I don't understand how you could be stressing the frame when there is virtually no movement - I'd think the actual sway occurrences would be more damaging.

    I used a Propride 3P for two seasons before the new 5er and i'll say that towing a 5er or a TT with a Propride feels about the same.

    You are thinking that if there is no movement, then there is no force.

    That is incorrect. The force is still there. It is just being stopped from moving by the hitch AND what it is connected to... BTW, I feel that the reciever is the most likely place where the results of this force will appear. It may take awhile, but metal can and does fatigue if the force is high enough. Both the HA and the PP can put signifignant sideways force into the reciever... There have been pics posted on tis forum in the past of recievers that failed as a result.
    There is a signifignant difference in operation between hitches that virtually move the pivot point, and the one that physically moves the pivot point. The Pull Rite is the best design in this respect.. Of course it has some drawbacks in other areas.. There is no free lunch.
  • RinconVTR's avatar
    RinconVTR
    Explorer
    Feb 07, 2016
    Anti-sway devices do not remove the external forces...they either cover them or absorb them.

    All friction type WDH and standalone mask the issue and provide assurance that is things get squirely these devices help reduce the effect. SAME WITH ELECTRONIC TRAILER STABILITY CONTROL - FYI!

    The Hensley and Propride do not mask anything. They are not a Band-Aid. They change the pivot point of the ball to basically a point near the rear axle like a 5th wheel.

    Hensley strut and connection point failures demonstrate how much force is involved within these virtual pivot point hitches.

    Propride is a slightly improved version of the Hensley, with its own pro as well as cons, and uses massive bolts and welded "yoke" frame instead of struts and pins. This should also give you an indication of what they must withstand.

    There is indeed more force placed on the TV and trailer using VPP hitches, there is absolutely ZERO doubt about it.

    But I don't believe its beyond what either of these frames can handle in any case, UNLESS the TV or trailer is overloaded beyond capacity.
  • 4X4Dodger's avatar
    4X4Dodger
    Explorer II
    Jan 26, 2016
    jmtandem wrote:
    I am of the opposite opinion. I believe anti-sway bars are a necessary insurance. Under perfect conditions, they may not be needed. However, driving conditions can be unpredictable and change in an instant. i.e., extremely strong wind gusts, swerving to miss a obstacle in the road or an animal darting across the road, etc. Driving properly is fine and dandy, but also may require drastic evasive actions when lease expected.


    None of the things you mentioned should ever put a trailer in a sway situation. Sway is defined as when the trailer is trying to go faster than the tow vehicle and is characterized as increasing arcs of oscillation. It is not a gust of wind or an 18 wheeler bow wave hitting the trailer for a second and moving it around a little. That is not sway. Your insurance should not be a sway feature on a hitch but the trailer only brakes. That is the only thing that can slow the trailer speed down enough; hitches don't slow the trailer. Think through sway, it cannot occur going uphill, the trailer is drag or trying to go slower than the tow vehicle. It cannot sway. Use the trailer brakes, that is what they are there for if you think you will be having a sway episode. The guys that deliver trailers to dealers from the factory don't use sway features and know that if the trailer has at least ten percent of the total trailer's weight on the tongue, it won't sway.


    x2 Exactly. And furthermore if you understand how to handle the trailer in an emergency situation, a very unlikely event if you are driving correctly, you would understand what to do and when to do it to avoid problems. Anti sway bars are NOT going to save you from an accident or make you safer. At most they just give you a measure of false confidence that in itself is probably more dangerous than anything. Knowledge and experience are the keys, not expensive unnecessary add-ons.
  • jmtandem's avatar
    jmtandem
    Explorer II
    Jan 22, 2016

    From reading this forum for a long time I think the biggest problem is most people don't even know what "true sway" is.

    They think when a big rig pushes them around it's sway. It's not.

    They think when a side wind hits them and pushes them around it's sway. It's not.

    I've heard it time and time again on here. "You need to put sway control on your trailer just in case." I got news for them. Trailers just don't decide to sway. If they are manufactured wrong, they will sway. If they are manufactured correctly, they won't. It really is that simple.


    Your comments are well received. I live in Nevada five miles from where the great American author Mark Twain in his book Roughing It wrote about the Washoe Zephyrs, incredibly strong winds. In Nevada if you don't know how to tow in the wind you probably won't get out much. And wind is not sway, just as you indicated. Neither is sway going down a long hill with a curve at the bottom on a slippery road and the trailer pushes the tow rigs rear end into a jackknief situation. There is no sway, just poor traction. A WD hitch with a sway feature will not help. In the past some hitch manufacturers felt that in slippery situations sway control can actually be detrimental.

    Thousands of every type of construction trailers are towed millions of miles a year without sway control or mitigation. The whole sway fear should be tempered by facts not hype. How many weigh their trailer loaded for camping and then the tongue? Or, do most just purchase a hitch and hope for the best not really knowing what the trailer's weights are? For those that want peace of mind or 'insurance' go weigh your tongue and calculate the tongue weight and see if it is within limits. That, not a hitch, is peace of mind and insurance. And then if they want to throw a WD/sway feature hitch on as well, at least they know their trailer values are
    good and the hitch is not there to save them, just to go along for the ride.

    As far as the OP's original question, I am aware of Airstream frames being damaged by overly aggressive WD hitches, not so much from the sway feature, but too much tension on the bars. There is lots of information about this especially as it relates to the Equalizer hitch damaging the Airstream tongues (or not). If interested spend a quality evening on their forums and you will see plenty on this issue.
  • Turtle_n_Peeps's avatar
    Turtle_n_Peeps
    Explorer
    Jan 22, 2016
    jmtandem wrote:
    Turtle,

    Sadly, reading resposes to this and other threads on sway, most people will try to deal with the hitch to eliminate any possibility of sway instead of being sure the trailer is well designed and properly loaded.


    From reading this forum for a long time I think the biggest problem is most people don't even know what "true sway" is.

    They think when a big rig pushes them around it's sway. It's not.

    They think when a side wind hits them and pushes them around it's sway. It's not.

    I've heard it time and time again on here. "You need to put sway control on your trailer just in case." I got news for them. Trailers just don't decide to sway. If they are manufactured wrong, they will sway. If they are manufactured correctly, they won't. It really is that simple.

    I have designed and built a few trailers in my time. I designed and built a really nice flat bed race car trailer. It towed beautifully! Both empty or full, 40 MPH or 80 MPH it didn't matter.

    Then I wanted an enclosed race car trailer so I enclosed it. After I got the enclosure on it I took it down the road for a tow. The thing wanted to kill me with crazy sway! What the.............???????

    I took me a few minutes to figure it out. I designed and built a really HEAVY ramp door on the back. I made it nice and heavy so it would not bend. Problem is it took a ton of tongue weight off of my trailer. Oooooooooo fudge!!! When I put my car in the trailer it towed great!!! Empty is was a nightmare!

    So I built a real heavy work bench in the front and also put a kitchen in the front along with a real heavy tool box.

    Know what? My trailer tows beautiful again!!! Lesson learned.

    It's lessons like this that make me cringe when people say they want to build gen set mounts on the back of their trailer or mount 4 bikes on a heavy rack on the back.
  • bid_time's avatar
    bid_time
    Nomad II
    Jan 21, 2016
    mkirsch wrote:
    ...How long before something breaks?
    I'll be able to answer that question as soon as someone reports on here that Their's Broke! 10 years on here so far and no such report. So it either doesn't happen or it takes more than 10 years to happen. I believe I know which answer is correct.

    That being said, loading correctly should always be the first step.
  • jmtandem's avatar
    jmtandem
    Explorer II
    Jan 21, 2016
    Turtle,

    Sadly, reading resposes to this and other threads on sway, most people will try to deal with the hitch to eliminate any possibility of sway instead of being sure the trailer is well designed and properly loaded.
  • Turtle_n_Peeps's avatar
    Turtle_n_Peeps
    Explorer
    Jan 21, 2016
    jmtandem wrote:
    By the way, a sudden and severe swerve while towing a trailer can/will cause the trailer to sway as demonstrated in videos demonstrating the effects on a trailer with and without a sway control hitch.


    Please provide the links to the videos you are referencing. I would like to watch them. Hensley, ProPride and PullRite make wonderful hitches for WD. PullRite is a little heavy at 400 pounds but it is likely the best of the three. And if the trailer is not well suited for towing the hitch can 'bandaid' a serious situation so sway is 'contained' so it cannot get out of control. Sway is still there, still trying to occur, it is just controlled. And worse, there is still something wrong with the trailer.


    Great post and spot on the money. Get the trailer right FIRST.
  • jmtandem's avatar
    jmtandem
    Explorer II
    Jan 21, 2016
    Can you post a link to this magazine article?

    It sounds very interesting.

    Ron


    Ron,


    I don't have a clickable link. But here are the issues and pages.


    Airstream Life Magazine Summer 2010, page 49 "Why is my hitch Crooked?"

    Fall 2010, also page 49 "Secrets of Torsion Bars and Sway Control"

    Winter 2010, page 50, "Towing, the weakest link"
  • Ron_Gratz's avatar
    Ron_Gratz
    Explorer
    Jan 21, 2016
    jmtandem wrote:
    ---A couple years ago in the Airstream magazine sway was well defined and exlained using physics, moment arms, and loading issues, not opinions.---
    Can you post a link to this magazine article?

    It sounds very interesting.

    Ron

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