Sway control for ice?

[Inland RV Center, In]

Originally Posted by Ron Gratz

It always puzzles me why some believe that one type of friction-based sway control (such as a friction bar) must not be used in reduced-traction conditions while, at the same time, they believe another type of friction-based control (such as a Dual Cam) will work properly in any type conditions.

Ron

Reese dual cam hitches operate on torsion, not friction.

Andy

[Eric 28]

Andy, Our AS is an 2003 Safari 28 SO. The hitch wt. is 1250 lbs. I have 800 pound bars. They bend all of 2", if not more when I am hooked up. I am getting my information right out of the AS manual. I also had to go to a class 5 receiver.

[bryanl]

They are is disagreement. I'm still confused

That is why bald assertions, absolutes and other such truck need to be taken with a grain of salt. If you don't want to be confused by conflicting statements and grandiose assertions, you need to understand what is going on and why.

One common problem is about the nature of sway control and thinking that it is something more than it is. As anyone who has broken off the ball on a simple friction type sway device should know, the forces applied by sway control devices are rather small. What that means is they won't make much of a difference when going slow on slick surfaces unless you have extremely slick surfaces where their small forces can actually do something. That means trying to turn a corner and things are slick enough that the sway control can resist articulating the rig. That usually means slick enough you can't walk on the surface.

The comment about braking is also in this line. That's a lot of inertia back there and there is no way you can slow it down and keep it back there without some control. Adding chains with appropriate trailer braking is second only to letting it drag to a stop - and the drag distance on a slick surface can be quite a ways.

I remember one winter by Klamath Lake when a trucker passed us - he was fishtailing on down the road as far as I could see. He must have made it as I didn't see him beside the road. An SUV on Willamette Pass didn't- he passed us and did a real nice, slow 360 into a snowbank at the side of the road. Took us a lot longer to get home that Christmas than usual.

A lot of this also relates to why automatic transmissions are often better in slick conditions and why the 2 starts off in second gear.

Know why and retain a bit of skepticism about people who are really absolute about complex things and you'll be ahead in making sense of conflicting claims.

[Inland RV Center, In]

Originally Posted by Eric 28

Andy, Our AS is an 2003 Safari 28 SO. The hitch wt. is 1250 lbs. I have 800 pound bars. They bend all of 2", if not more when I am hooked up. I am getting my information right out of the AS manual. I also had to go to a class 5 receiver.

With those weights, your in great shape.

Andy

[Eric 28]

Andy, I'm happy to know that I'm in great shape.
Thank You

[Ron Gratz]

Reese dual cam hitches operate on torsion, not friction.

According to page 2 of

http://www.reeseprod.com/fitguides/pdf/N26000.pdf:

MAINTENANCE:
9. DO NOT GREASE THE CAM AND CAM ARMS. The Dual Cam was designed to use metal-to-metal friction. Heavy greasing of the cam and cam arm surfaces with affect performance. If noise is offensive, a very light coating of lubricant, such as Vaseline, may be used. Tongue weights over 1,200 lbs. may require a light coating of grease to reduce friction and prevent excessive wear.

Ron

[Inland RV Center, In]

Originally Posted by Ron Gratz

According to page 2 of

http://www.reeseprod.com/fitguides/pdf/N26000.pdf:

MAINTENANCE:
9. DO NOT GREASE THE CAM AND CAM ARMS. The Dual Cam was designed to use metal-to-metal friction. Heavy greasing of the cam and cam arm surfaces with affect performance. If noise is offensive, a very light coating of lubricant, such as Vaseline, may be used. Tongue weights over 1,200 lbs. may require a light coating of grease to reduce friction and prevent excessive wear.

Ron

Ron.

It's true that the Reese dual cam bars also have a friction factor. But, it's very small compared to the torsion.

As you make a turn, with the dual cams, the torsion on each bars, "UNEQUALLY" increases. That's why the end of the bars are different from the very end to about 3 inches forward of that. In a turn, one bar moves forward and the other moves rearward. Because of the different shape, that's where the unequal increase takes place.

That is the very reason they work so well, up to and including returning your tow vehicle to a straight line, if you let go of the steering wheel.

Torsion does that, not friction.

Reese is a great company, but they are dead wrong in their "what rating" hitch to use, that totally disregards the type tow vehicle you may chose to use.

That subject will addressed in articles that will soon be published to 2 different magazines, that are familiar to Airstream owners.

Andy

[ROBERTSUNRUS]

Originally Posted by CrawfordGene

I have asked a similar question asking about suggestions for towing in snow. The answers were characterized by complete disagreement about what is best except for one thing—drive very slowly. That left me confused. We have escaped snow so far and in the shoulder seasons there are usually more clear days and roads between the snowy ones around here.

What Bob says—I have an Equalizer too—makes sense, and so does what Andy says. They are is disagreement. I'm still confused. It seems to me without the Equalizer, the trailer would be less stable and more likely to do something unplanned.

And then there's the question about how to use the brake controller—change the settings or not? I got completely different answers to that question too. Still confused.

Gene

Hi, one thing I was trying to say was that if I remove the friction devise on my hitch [Equal-i-zer] that would mean removing the spring bars. So what Andy is saying [correct me if I'm wrong Andy] to remove the friction devise does not apply to my brand hitch.

Also some people set up their trailer as a science, but in reality, I consider everything to be at a happy medium; Therefore I will not stop and readjust anything because of changes in situation such as: rain, snow, fog, smog, hot, cold, windy, sandy, gravel, dirt, clay, mud, time of day or night, temperature, Tank levels, Etc. Etc. Etc.

[catson4]

As an OL' trucker, PLEASE , stay off the road with your travel trailers when it is Icy or Snow covered. Unless , of course you get caught out there. That is another story.

Friction sway controls ---- Just like ANDY says, NO NO NO
I have over 110 rounds between Seattle & Anchorage back in the dark ages. Trailers DO NOT LIKE ICE. Be it a freighter 5th wheel , campin' 5th wheel or a travel trailer.
Remember that it is better to be able to STOP than to Go.
So if you are goin' in the snow & ice, get some TIRE CHAINS for that trailer as well as the TV.
CHAINS ON EVERY TIRE ON EVERY AXLE

AND GO SLOWLY & with GOD..

[Ron Gratz]

Originally Posted by Inland RV Center, In

It's true that the Reese dual cam bars also have a friction factor. But, it's very small compared to the torsion.

As you make a turn, with the dual cams, the torsion on each bars, "UNEQUALLY" increases. That's why the end of the bars are different from the very end to about 3 inches forward of that. In a turn, one bar moves forward and the other moves rearward. Because of the different shape, that's where the unequal increase takes place.

Andy, I believe I understand what you are saying, and I also believe I must respectfully disagree with your assessment of the relative importance of the friction forces between the cam and the WD bar.

We do agree that, if the TT swings relative to the TV, the rear end of one bar will move forward relative to its cam while the end of the other bar will move rearward relative to its cam. However, the relative longitudinal displacement between the center of the bar detent and and the center of the cam will be less than 0.1" per degree of yaw angle. A yaw of 2 degrees would cause the rear of a 30' TT to move laterally about 1' relative to the straight-ahead alignment. And, a yaw of 2 degrees would cause a relative displacement of less than 0.2" between bar and cam.

If the DC is properly installed and adjusted, the slope of the end of the WD bar forward of the center of the cam will be approximately equal to the slope rearward of the center. This means that, if the TT swing is limited to an angle of about plus or minus 10 degrees, both bars will be raised nearly an equal amount.

Let's assume the TT swings 5 degrees. Relative displacement will be less than 0.5" and, assuming the bar slopes are about 30 degrees, each bar will be raised about 0.25". A WD bar which is loaded to its rated value will have an end deflection of around 4" relative to the unloaded end position. So, a 5-degree swing will increase the end deflection (and, hence, the load on the bar) by about 6%. And, the increase on each bar will be approximately EQUAL.

That is the very reason they work so well, up to and including returning your tow vehicle to a straight line, if you let go of the steering wheel.

Torsion does that, not friction.

Again, I must respectfully disagree. Even if there is some small amount of unequal loading of the WD bars when the TT swings, the resulting effect is almost entirely a pitch-axis torque on the hitch and almost no yaw-axis torque. Sway control requires yaw-axis torque.

The yaw-axis torque results from the longitudinal tension or compression induced in a WD bar as the end of the bar exerts friction force on the cam to try to prevent relative displacement between bar and cam. The axial force in the bar might be around 2-3 times the vertical force acting on the end of the bar.

If one bar carries a tension force of 2500# and the other bar carries a compression force of 2500#, then, depending on the lateral distance between the front ends of the bars, the DC system might generate a yaw-axis torque of about 2000 lb-ft -- about 4 times the torque which can be generated by a single friction-bar sway control.

The reason a DC makes it easier for the rig to return to zero relative yaw is because the friction force between bar and cam is less when the rig is returning to the "centered" position than when the TT is swinging away from centered. In fact, if the slope angle at the end of the WD bar is around 30-35 degrees, the bar slope tends to push the cam back toward the center of the detent with a force which is almost equal to the friction force which is trying to prevent relative displacement.

Therefore, when the TT is trying to move back to "centered", the net longitudinal force between bar and cam can be essentially zero.

As Reese states: "The Dual Cam was designed to use metal-to-metal friction."

And, the friction-based design works very well.

Ron

[bryanl]

And, the friction-based design works very well.

which is, perhaps, why the simple friction bar tends have the majority of the market.

I think many seem to miss the idea that sway control devices are damping devices like shock absorbers and some devices even use the same technology. Friction, however, is easier, simpler, and less expensive and works just as well in the light duty sway damping application.

But marketing hype has been bought and that tends to solidify perceptions over careful inspection and evaluation. That leads to head-butting discussions which don't help anyone.

[Inland RV Center, In]

Originally Posted by Ron Gratz

Andy, I believe I understand what you are saying, and I also believe I must respectfully disagree with your assessment of the relative importance of the friction forces between the cam and the WD bar.



Again, I must respectfully disagree. Even if there is some small amount of unequal loading of the WD bars when the TT swings, the resulting effect is almost entirely a pitch-axis torque on the hitch and almost no yaw-axis torque. Sway control requires yaw-axis torque.

And, the friction-based design works very well.

Ron

Ron.

If the Resse is friction only, as you suggest, then please explain why you can make a 15 degree or so turn, in a parking lot, stop and get out, and look at the front of your tow vehicle.

You will find that the vehicle is leaning to one side.

Friction cannot do that, but torsion can, and does.

Andy

[Inland RV Center, In]

Originally Posted by ROBERTSUNRUS

Hi, one thing I was trying to say was that if I remove the friction devise on my hitch [Equal-i-zer] that would mean removing the spring bars. So what Andy is saying [correct me if I'm wrong Andy] to remove the friction devise does not apply to my brand hitch.

Equalizer brand, does not offer "friction" sway control as they claim. But they do offer torsion. However, since their bars are extremely heavy duty, they bend very little when hitting a bump. That causes the road shock to go to the trailer.

That brand hitch was at the top of the "loss of control accident" list. Next in line was "no load equalizing hitch at all."

On the other hand, if the bars flexed when hitting a bump, then the amount of road shock transfered to the trailer becomes less. The more flex, to a point, the less transfer of road shock.

There is not a single friction type sway control, that knows when the rig is in a turn or straight line.

A torsion type sway control, does have that ability.

A friction type sway control can never seek minimum friction, when it's not moving. Since it's not moving, it's at zero friction. Should the rig be in a turn, the friction is working against you to straighten back out.

A torsion sway control seeks minimum stress at all times, since it has some stress on it's bars at all times, assuming the installation was correct. Therefore when the rig is in a turn, the torsion is working "with" you since it wants to return to zero, if possible.

Theories are great and usually have merit of some form or another.

But the actual, difference between hitch tests must be made, by the same person who outlines a theory of why the cheapest of load equalizing hitches is the best, or why the most expensive is the best.

How much, this much, that much, but, but, but, makes nice discussions, math, or theory, but it does not provide the facts of physics, nor scale weights, or actual road tests.

Today, we are reading more posts from people who thought their "super heavy duty" rig was the best, until they decided to alter the hookups, based on facts.

Many of those same people have posted here, of "wow" what a difference, and improvement.

I am more than sure, that list of owners will grow.

I also understand, that posts such as that, will never carry any weight with those that have differences of opinions.

Then we can all go back to basics and say, with absolute assurance, that when your trailer get beat up from excessive road shock, that no insurance company will pay to correct those problems, since the loss is not sudden, accidental, or direct, but unquestionably, long term.

Long term, what?

Shock and vibration from excessive rigging.

Andy

[purman]

I'm with the truckers. Put Chains on your trailer. this will help keep it in line and stop it from skidding all over the road when trying to stop AND GO SLOW.

I haven't towed the AS in the snow but have towed my flatbed with the tractor on it. It did come around on me when trying to stop once. NOT FUN.. chains would have prevented that.

I would disconnect the sway control but keep the equalizer on just not as tight.

[StevenG]

This may be obvious, but sometimes the obvious needs repeating. DO NOT use your cruise control! You need to be able to feel the road and traction, or lack thereof, through your foot on the accelerator. Best advice, wait until Spring. But at any rate, Good Luck!
Steven

[Gene]

I'm still trying to figure this out. I can't understand the theory posts as I'm not trained in that science. I'm not glad to read the Equalizer is: "That brand hitch was at the top of the "loss of control accident" list. Next in line was "no load equalizing hitch at all."" Would that mean an Equalizer was better than no WD hitch on snow? Would the Equalizer perform better on snow if the friction points were greased?

I expect that if I were able to get the experts together in one room and question them for several hours or days, I might understand this and be able to make informed decision. That's not likely to happen (not many people like to subject themselves to my cross-examination; just ask my wife and some witnesses from my professional past). Studying the accident reports would be useful, though I would ask if they were accurate. Tests on various WD hitches and driving without them may be sponsored by someone with an ax to grind or badly done.

I don't think this thread has gotten to the "headbutting" stage yet since there haven't been any direct insults. I commend the effort to explain sincerely individual points of view. However, I'm unsure there's enough space in the thread to explain each point of view so clearly and with such detail that it would be conclusive to me.

We could have the Summit on Winter Driving at my house, but lodging and food is your problem. Well, I have a lot of space to park, but no hookups. Right now it's snowing so maybe the only person to make it here would answer the question. Every road to my house has sharp curves, slick surface, steep grades and areas that have ice most of the winter. My 850' driveway isn't so great either. Leaving would be even more fun. One road has a reservoir after a sharp, steep curve (can you swim?). You could tow up and down these roads until there was only one trailer left and see how it's hitched up.

So, keep posting, maybe I'll get it. Otherwise, I'll probably come upon snow someday and find out for myself, just like most people do. I will drive slowly, the rest I don't know.

Gene

[bryanl]

That brand hitch was at the top of the "loss of control accident" list.

since the list is not public nor published and strictly anecdotal, it is probably best to take the assertion with a grain of salt,- especially when published crash statistics do not support the idea of load leveling devices (nor sway control devices) being a cause of accidents and the sample size of RV trailer crashes is so small as to make any such measurement meaningless and the problems with load leveling and sway control concepts being confused, _and_ the conflation of the equalizer hitch with the Lindon brand Equal-i-zer hitch and ...

as for the theory posts, don't get lost in the trees when all you need to do is see the forest.

First, you need traction both on the tow vehicle and the trailer. That is why they have traction devices and road control procedures. Chains! on both truck and trailer.

Second, you need to be able to exercise control in order to stay on the road where you want to be. Load leveling and sway control are way down the list of things you need to worry about on this topic. Speed is perhaps the number one issue as a component of basic uncommon sense that has you on the road when it would be better not to be.

[Ron Gratz]

Originally Posted by Inland RV Center, In

Ron.

If the Resse is friction only, as you suggest, then please explain why you can make a 15 degree or so turn, in a parking lot, stop and get out, and look at the front of your tow vehicle.

You will find that the vehicle is leaning to one side.

Friction cannot do that, but torsion can, and does.

Andy

Andy,

If the TV and TT are aligned straight ahead (zero relative yaw), the upward forces on the rear ends of the WD bars creates a torque on the hitch which acts only about a pitch axis. This torque tends to lift the rear of the TV up and force the front of the TV down.

If the TV and TT could be aligned so that the TT is at 90 degrees to the TV, the upward forces on the rear ends of the WD bars would create a torque on the hitch which would act only about the TV's roll axis. This torque would tend to lift one side of the TV up and force the other side of the TV down.

When the TV and TT are aligned at an angle between 0 and 90 degrees, the upward forces on the rear ends of the WD bars creates a torque on the hitch which acts about both the TV's pitch axis and its roll axis. The component of torque which acts about the roll axis tends to lift one side of the TV up and push the other side down.

No matter what kind of WD system is used, if the bars are loaded and the relative yaw angle is non-zero, there will be a component of torque acting on the hitch which would tend to cause the TV to lean to one side. This is not unique to the Dual Cam.

I fully agree that it is WD bar loads rather than friction forces which tend to make the TV roll. However, please keep in mind that sway control is primarily produced by yaw-axis torque. Flexure of the WD bars does not produce yaw-axis torque. With the Dual Cam, it is the friction-induced longitudinal tension and compression forces in the bars which produces the yaw-axis torque.

Ron

[Ron Gratz]

Originally Posted by Inland RV Center, In

Equalizer brand, does not offer "friction" sway control as they claim. But they do offer torsion. However, since their bars are extremely heavy duty, they bend very little when hitting a bump. That causes the road shock to go to the trailer.

I believe that the Equal-i-zer hitch has a considerable amount of rotational friction designed into the socket assembly which holds the front end of a WD bar. In fact, the socket assembly is clamped against the hitch head using a bolt which must be torqued to 45-60 lb-ft. When a lateral force is exerted on the end of a WD bar (i.e. when the TT tries to swing and the side of the A-frame pushes laterally on the end of the bar), the force multiplied by the length of the bar induces a yaw-axis torque which is transmitted to the hitch head via rotational friction between the socket and head.

Additional yaw-axis torque is generated via the longitudinal tension and compression forces in the WD bars resulting from friction forces between the bars and the L-brackets.

If sway control could be explained simply by flexure (a.k.a. "torsion") of the WD bars, then only the WD bars would be required. There would be no need for a "friction bar". There would be no need for the cams of a Dual Cam. And, there would be no need for the four friction points of the Equal-i-zer.

Furthermore, the Equal-i-zer could not produce any sway control because the "unequal lifting" argument which was offered for the Dual Cam does not apply to the Equal-i-zer. The Equal-i-zer's L-brackets are flat and there is no "bend" in the end of the WD bar.

There is not a single friction type sway control, that knows when the rig is in a turn or straight line.

If by "friction type sway control" you are referring to this type (http://www.draw-tite.com/fitguides/pdf/N3400.pdf), then I agree with you. As far as I know, the Dual Cam is the only control which can "sense" when there is misalignment. However, it is the TT tires which provide almost 100% of the "return to center" force when the TV and TT are not in a straight line.

A torsion type sway control, does have that ability.

Andy, can you elaborate how a "torsion type" control knows how the rig is in a turn or in a straight line?

A friction type sway control can never seek minimum friction, when it's not moving. Since it's not moving, it's at zero friction. Should the rig be in a turn, the friction is working against you to straighten back out.

Actually, when a friction device is not moving, it is producing the maximum friction force. The static (non-moving) coefficient of friction is almost always greater than the kinetic (moving) coefficient. It is the static friction from a friction-type sway control which "stiffens" the yaw-axis connection between TV and TT and tends to "lock" them together.

Ron

[ROBERTSUNRUS]

Hi, as Ron Gratz stated, there is a certain amount of friction in the pivots on the head, of the Equal-i-zer, and even more where the spring bars are riding on the "L" brackets while doing double duty as weight distributing. I would also like to see proof, not hear-say, that my hitch is only better than no hitch at all. And if there are more problems involving the Equal-i-zer it just may be the fact that there are more in use. Percentages tell the true story.
Back to the subject, my tow vehicle, my trailer, my hitch [Equal-i-zer] and my driving skills, did just fine while driving in snowing conditions.