Dave,
Thanks for all the detail, its' very helpful.
Pete
--- In AirstreamList@yahoogroups.com, dtbw <dtbw_1999@...> wrote:
>
> On Aug 21, 2012, at 10:56 AM, "pete.woodhead" <pete.woodhead52@...> wrote:
>
> > I've been told to think about getting a different hitch, a ProPride, I
> > believe it's called, it's about $2500, but it's come so highly
> > recommended by a Streamer I respect,
> >
> Well, since we have ventured into hitch territory, I will throw my two cents, ok maybe a bit more that two cents, into the discussion. I would NOT tow without either a Hensley or a ProPride (same designer/different manufacturer, ProPride improved in some subtle ways, but NO more effective in precluding sway). Both Hensley and ProPride PRECLUDE sway, period. Other hitches attempt to dampen sway after the fact and for typical run of the mill sway do a decent job. The real monster under the bed is a phenomena known as resonate sway. Resonate sway is when the towing dynamics are induced, usually by an 18 wheeler passing from BEHIND you, to enter into a sway with a period (ie time it takes to sway from one side to the next and back) that is "resonate" with the natural oscillation frequency of the trailer/tow rig. When this occurs, there is NO warning, no chance to react with the trailer brakes, as the trailer heels over HARD to one extreme (ie no gently work up) and then the other. The rig goes totally out of control in an instant.
>
> I saw this first hand years ago as a kid. We had been following a Holiday Rambler running about a mile ahead. An 18 wheeler came blowing by us from behind, but it did NOT have much impact on our rig. When it got to the Holiday Rambler, things were VERY different. Just as the 18 wheeler's trailer rear end got about even with the Holiday's front end, the Holiday literally pulled almost perpendicular with the pavement and then instantly swung to the other extreme at which time, it tore loose from the tow vehicle as it flipped on its side. FYI, the guy was towing with a Reese Dual Cam which at that time was state of the art in sway control. That made a VERY lasting impression on me. I later learned in physics exactly what had happened.
>
> The same thing happened to a long time Airstreamer that we know while he was towing his 31fter in AZ with a Reese dual cam. He and his wife both commented that they had NO warning that the rig was about to swing violently until it was almost jackknifed. As was the case with the Holiday, it then swung violently to the other side and flipped itself and the tow vehicle over on their side. An 18wheeler blowing by them from behind was the culprit.
>
> The real problem with the Reese dual cam is that once the torsions bars disengage from the cams (ie in a turn or during a hard-over sway), there is ZERO sway control. The whole concept of the dual cam is that the cams act in concert with the torsion bars to LOCK the trailer and tow vehicle together during straight-line towing. The downward pressure of the torsion bars keeps them in the locked position of the cams and significant force (such as turning) is required to pop the torsion bars over the cam to allow the rig to pivot at the hitch. This works wonderfully to control the more typical tailwagging sway that CAN get out of control if left unchecked. When a Reese dual cam hitch is throw resonate sway it is NO match for the forces and the trailer simply rides over the cams and goes unlocked. I am not trying to scare ANYONE that the Reese Dual Cam is an unsafe hitch, in fact if the Hensley/ProPride technology had not been invented, the Dual Cam would be my personal choice (as it was for my parents, which predated Hensley coming to market).
>
> While coming back from Jackson Center with our 19fter when it was less than a year old, I had the occasion to get a first hand example of how well the Hensley worked to keep the trailer towing straight regardless of conditions. I was traveling along that stretch of I44 in northern Oklahoma. The speed limit is 75 and at times that seems more of a suggestion than a limit. I was cruising along a bit below traffic speeds (65-70) when I noticed in my rear view mirror that the trailer was leaning toward the curbside. There was NOTHING wrong with the way the rig felt and it was towing true as an arrow. I slowed and pulled onto the shoulder. I first inspected the Hensley and all was well, I then walked around the rig starting on the drivers side, and when I rounded to the curbside, BINGO, a blown tire. Now remember this is a single axle trailer. Blowing a tire on a single axle trailer is a recipe for the trailer to pull HARD toward the side of the blown tire. To make matters worse, on that day there was a crosswind coming from the roadside. In my case, there was no sign of pulling to one side, visibly, or in the way it was towing. A failed rubber valve stem was the cause of the tire deflating (Airstream had installed rubber stems rated at 60psi on tires that they recommended inflating to 60psi, go figure). SInce other than a ruined tire, there was no damage. I installed the spare, and continued my way home and then installed new tires, new steel 120psi valve stems and tire pressure monitoring on the Bambi. The Hensley proved its worth to me on that day as that situation could have been horribly different. Can I state that the Hensley save my butt and my rig that day, no, but the dynamics that should have played out that day certainly did not and blowing that tire was a non event overall. FYI, a short trailer is just as likely to sway as a long one, so NO the Hensley is NOT overkill on the Bambi.
>
> About a year after my Bambi incident, the same thing happened to couple towing a new Bambi (ie valve stem failure). They were towing with an Equalizer hitch. When the tire deflated, the rig pulled hard in the direction of the deflated tire, the driver may have overreacted at bit and the whole rig flipped, totaling the Airstream and the tow vehicle, but fortunately no injuries. The difference in my mind, my Hensley!
>
> One last comment that a fellow Airstreamer made. We were leading a caravan to Colorado (16 rigs). Along the way, the position of each rig with the exception of ours varied. There was a mixture of hitch brands, Equalizer, Reese, Hensley, etc. When we got to Colorado, the person came up to me and commented that he was ordering a Hensley as soon as he returned to Texas. At first I thought he must have had a scare on the way up, but he told me no, that what had convinced him was that as he had followed various trailers on the trip. His observations were that on the non-Hensley rigs, there was always SOME side to side sway as the wind, 18wheeler, etc would impact the aerodynamics of the rig, but with those being towed with a Hensley, NOTHING, not even the slightest side to side motion on the rear end of the trailer. That alone had convinced him that the Hensley was doing something VERY different than the other hitch/sway control combinations.
>
> Now a Hensley/ProPride will not cure the problem of too much trailer, too little tow vehicle, but even with an overly competent tow vehicle, resonant sway is still a possibility.
>
> I know that a person could tow a lifetime and NEVER encounter resonant sway, but it could happen on the next outing. The price of a Hensley or ProPride is insurance and peace of mind that resonant sway simply is impossible as both effectively move the "pivot" point of the combined rig to a point near the front axle of the tow vehicle. The trailer mechanically can't induce a pivot at the hitch. Only from the tow vehicle side of the hitch can a pivot be induced. They do this through a 4 point, articulating linkage. When things like 18 wheelers came up from behind, you WILL feel the force pushing the ENTIRE rig first toward the shoulder and then pull toward the centerline, but it is NOT a white knuckle experience that you hope you survive.
>
> There will likely be some on the list that will disagree with me and everyone makes their own decisions regarding their comfort zone when it comes to towing. No one is required to spend the money on a Hensley or ProPride, just remember that you are betting that you will never encounter resonant sway.
>
> David T.
> '99 35ft Limited
> '02 Bambi LS
>
>
>
>
> [Non-text portions of this message have been removed]
>
This site is not sponsored by or affiliated in any way with Airstream Inc, Thor Inc, or the WBCCI.
0 comments:
Post a Comment