Anti Sway Systems - Necessary or Marketing Con?

[4X4Dodger]

This may open a Pandora's box and bring down a lot of criticism on my head but the question really remains a valid one I believe.

Are Anti Sway bars (Like the Hensley) really necessary or a crutch for those that either cant drive a trailer effectively or have an out of balance rig? Are they a multi million dollar business out to convince you you really need one when you dont OR are they really filling a needed gap in TT towing safety?

First a little background: Despite my newness to this site, I have been towing trailers on and off most of my life (a good 45 years of driving) and towed everything from a small U-Haul to a 53 footer with a GVW of 80,000lbs. I have held a Class A CDL with endorsements for Doubles, Triples and Tankers for over 20 years and owned my own trucking company (10 trucks/25 trailers doing logistics) I have for a good share of my life lived overseas where I have seen every possible combination of tow vehicles and trailers most of which most Americans would be horrified to think actually are driven on the road.

No matter what I have towed or with what vehicle I have never felt the need for an Anti-Sway system. Right now I tow my 30 foot Gulfstream Innsbruck with my Dodge 2500 4x4 HD 5.7L Hemi.

I'd like to hear the arguments for and against. Are these systems just taking the place of proper training and practice or are they a true necessity? AND do they instill a "False sense of Confidence" when driving an unbalanced or badly loaded Rig?

NOTE: I am not trying to be willfully provocative here but am truly interested in your thoughts.

[TomG2]

There are at least two versions of "Sway", which complicates the whole process. Anyone who has driven an overloaded pickup will know one variation. The steering feels like the front end is off the ground and the rear end swerves from side to side. That is the one that people confuse with sway caused by trailer problems. WD might help a little with the overloaded rear axle, but won't cure a swaying trailer. Sway control won't help an overloaded tow vehicle from wallowing down the highway. Two different scenarios, two different cures.

[4X4Dodger]

E&J push'n wind wrote:

4X4Dodger wrote:
E&JPNW wrote: "Now place a 25' to 35' trailer with all of its weight and the lever it has between the center line of the axle assembly and the tongue coupler. I wish I knew how to place illistrations on here, I will try to paint a word picture. Picture an arrow pointing at the pivot point in a lateral fashon at both a 5th wheel hitch and a conventional hitch. This of course is latter force. Sure 5th wheel hitches have lateral force exerted against them. The difference is that because of its placement over the center line of the rear axle (or slightly forward of it) you lose the lever effect that a conventional hitch would exert against the TV because of its distance from the center line of the rear axle."

Answer:

I believe you are thinking in only one plane. The ball hitch is either equal to or BELOW the frame of the truck. this position is much more difficult to move the truck on a lateral plane than the 5th wheel.

I'm speaking in terms of through the length of the vehicle, not the height of the vehicle. You will be able to rock it in a "fish tail" motion. You will not be able to as effectively with a 5th wheel hitch.

I've got to ask the question, what are you thinking of when we use the term, "lateral force?" My understanding is, a force from the side in some fashion, again through the length of the vehicle on a horizontal plane. So yes, for the sake of our discussion I am thinking in only one plane as these are the forces exerted from a sway condition.

The 5th wheel is much higher ABOVE the frame with most of the trailer weight still above that to act as a lever against the 5th wheel and the frame. This equals a longer lever arm = more force. Thus you need that big plate of the 5th wheel to react out those forces down thru the frame.

In this picture, you are looking at this from a vertical plane, top down through the fifth wheel. I believe what you are describing is pitch. A vertical side to side leaning. If you are understand this to be sway, then I can certainly understand your dilemma as an anti sway device would certainly NOT not help in any way resolve this condition.

But this has little to do with TRAILER sway. What you are talking about would be the trailer swaying the TV. If the TV is doing its job and the rig is set up correctly that's not going to happen (except in extreme cases of out of control stops or similar)

Answer this simple physics question for me:

Tell me what two principals of Physics are represented by the HAND CART? (the two wheeled upright kind)

I don't ask this to embarrass you but to understand and hopefully show you that the physics you believe are reacting on the TV just aren't correct.

4X4Dodger, I'm not embarrassed. I've explained that I'm not an engineer and I'll add, neither a physicist. All due respect to you, I suspect neither are you, though I could be wrong. I think if you were, we would have a mathematical explanation of your hypothesis. I've seen/read comments on this forum from engineers and they are very descriptive in their scientific language and explanation of things. You and I are having a time of it trying to describe our point of view.

So.., I'll ask you to explain yourself with the hand cart principal and ask you how that applies to what we are talking about for me and the sake of other readers.

Think about this by looking at the design of most of these sway bar systems, they simply react out the forces of the trailer's side to side motion by exerting a countervailing force against the tongue. NOT THE TV. If your hypothesis were correct all that bar and chain mechanism that works against the trailer would be aimed FORWARD.

They work in unison on a lateral plain. At the risk of starting a fire storm, the premimum namely the HA and PP are designed so that the trailer CANNOT turn (sway) unless there is input from the TV. I invite you to look at the sticky in the travel trailer section on the HA and how it works. The other conventional hitches typically use friction of some sort to counteract a sway condition where the trailer is whipping side to side. Kind of like fish tailing in a manner of speaking. The difference between the conventional friction type is that friction can be overcome. With a PP or HA, if the hitch is in tension it shouldn't be able to. In theory the whole unit (TV & TT) would move as a unit.


E&J: "I'm not saying that there arent lateral forces on a fifth wheel hitch, I'm saying there isn't leverage in the same manner as a conventional hitch."

Answer: leverage is leverage it changes with the length of the lever. Not with the hitch type. If anything the 5th wheel is able to exert MORE leverage than the ball type.

Please explain? On a horizontal plane where a 5th wheel is able to exert more leverage? Am I missing something?

4X4Dodger, I've asked this question before and you still have yet to answer it. Please describe (on a horizontal pane) the leverage in relation to a 5th wheel hitch? I can't see it, unless I'm missing something. I've described I think quite clearly the leverage in relation to a conventional hitch on a horizontal plane. Unless we are on different terms (and I think we are), lateral to me is on a horizontal plane.

5th wheels are placed over the axles PRIMARILY for WEIGHT reasons. This takes advantage of the Carrying capacity of the P/u. There MAY be some advantages of stability (but not if the trailer is loaded wrong) but the reason 5th wheel travel trailers were designed in the first place was to provide a much bigger trailer (with a much higher tongue weight) to meet consumer demand for more space and amenities...it was not to reduce sway.

My conclusions from looking closely at these hitches and thinking deeply about the problem:

The VAST MAJORITY of sway problems are driver induced or improperly loaded trailers (same thing really)

Sway bars were a response to a lucrative market niche of the above that wanted to have a mechanism that damps out their inputs.

"Sway bars" better described as equalizing bars or weight distribution bars/spring bars. If your idea of these is as I suspect, then you have a misunderstanding of what the function of these bars are for. As I have just more accurately described them, the PRIMARY purpose for these bars was originally to distribute weight between the TV and TT. Over the course of the evolution of these spring bars sway control has been incorporated into the design.

More often than not, a 1 ton or even a 3/4 ton truck will not need these bars to tow a TT as they have sufficient suspension to "carry" the weight of a given TT. Reality is there are more 1/2 ton TV (P/U's and SUV's) on the road than their larger counterpart TV's. This is where the weight distribution are absolutely necessary to properly carry a said tongue weight. Without these spring bars it would be very unsafe to tow these trailers though it is done by unwitting folks.

Again, at the risk of starting a firestorm. The HA and PP hitches have sway control incorporated into the design of the hitch. you can tow without the spring bars and still have the added benefit of sway control (horizontal plane). Many (not all) of the friction type sway control conventional hitches NEED the spring bars as this is part of the source of friction.

While this product may have it's benefits under certain road conditions and driving conditions (driver input) They are NOT NECESSARY to haul a trailer safely.

If you have a 1 ton or in many cases 3/4 ton truck, I think you'd be hard pressed to get an argument. However, look in the owners manual of vehicles that are designed to tow in some capacity and they will state that you need a weight distribution hitch to tow weights greater than X. These hitches that you are adamant about not needing and blantantly stating are not a safety device is quite irresponsible IMHO. For someone to read this and view you as an "authority" (yep they are out there) puts them at risk and everyone around them.

We have two things that we are talking about. 1) anti sway device, and 2) (I bring up) weight distribution. While they are not necessarily one and the same, in many instances they are simply because this is how the MFG's have decided to make them. With a conventional hitch you can have one without the other, you have to know what you are getting. I will state that having a weight distribution hitch may be necessary depending on the TV and the trailer behind the TV. While it is good to have and can be a safety device, sway control may not be absolutely necessary. Again, this depends on a lot of factors including the size of the TV & TT, loading of TT, hitch arangement, driving conditions etc.

Dont expect Trailer Life or its editors to ever print a fair article on this subject as there is just too much money at stake. TL is owned by Good Sam Ent. and so is Camping World. A great deal of income is derived from the Advertising and sales of these hitches by the GS Enterprises companies.

Playing the devils advocate, do you have anything to substantiate your claim? While I'm sure they derive revenue from advertising, and perhaps sales, you make a pretty bold claim without any proof. You are accusing them of the very thing you are doing, making claims without any proof. Hitch sales, really?

Unless and until an independent third party similar to consumer reports does some real scientific testing on these products and draws a conclusion one way or the other I will remain a healthy skeptic.

To all of those that use them and believe in them this is certainly your prerogative. But I think you should exercise some care in claiming that they are a SAFETY device. I don't believe that has ever been proven...

And while your stories of roll-overs and radically swaying trailers are compelling they remain only ANECDOTAL evidence...without real investigation, rather than a lot of assumptions of what really happened.

But one of the most telling things for me is this. The people who owned my trailer before me used one of these hitches and it came with the trailer. I have never bothered to assemble it or use it and I have absolutely no sway problem with driving this trailer. In fact my first trip with this trailer was Chicago to Minot ND (over 1000 miles) during one of the worst wind and snow storms of the season...and NO SWAY. Much of the time roads were snow and ice covered and the wind blew as much as 40 MPH and more..

All due respect 4X4Dodger, what's the difference between your anecdotal story and another. Should yours carry more weight because you feel so strongly about it? Also, to your point about it not being proven. It hasn't been dis-proven either.

edited by author for clarity

You make some good points and some valid ones. I wont bore you or other readers with my resume here I will PM you with some further info on that. Nor will I try to put the math down here...that is a useless exercise as most will be bored to tears with it and in the end it wont prove anything or change anyone's mind. Thse that understand it, already get what I am saying...those that dont the math will not help. However this conversation is getting too long and cumbersome. I will try to address your main points:

First: Weight Distribution and Sway are two different animals. However one can affect the other. We are talking about SWAY. And the mechanisms sold to as one manufacturer claims "eliminate it 100%"

Second: I do not feel strongly about this issue as I have said many times I am HIGHLY SKEPTICAL and have seen no proof that they do what they claim they do...meanwhile people are elevating them to the status of a NECESSARY SAFETY device. This I see as irresponsible and very possibly dangerous.

Third: The 5th Wheel and lateral forces; (for lack of a better descriptor) The one to two foot height that a 5th wheel sits above the frame of the vehicle is basically a Lever Arm for the trailer to use. This distance magnifies the forces. Downward, sideways (lateral) and along the longitudinal axis of the vehicle. These forces will RESULT in things like Yaw Pitch and Roll (same as an aircraft) upon the vehicle. The forces are reacted out by the TV and it's suspension (in most cases).

Fourth: you must take into account the Height at which the forces are applied as well as on which plane (in this case) This relates to the CG's of the individual vehicles and their combined CG. But again this has more to do with Weight Distribution and stability than it does with Sway.

Fifth: You Wrote;

If you have a 1 ton or in many cases 3/4 ton truck, I think you'd be hard pressed to get an argument. However, look in the owners manual of vehicles that are designed to tow in some capacity and they will state that you need a weight distribution hitch to tow weights greater than X. These hitches that you are adamant about not needing and blantantly stating are not a safety device is quite irresponsible IMHO. For someone to read this and view you as an "authority" (yep they are out there) puts them at risk and everyone around them.

You have misquoted be badly. I have never claimed they are not needed in some applications. Nor have I put myself up as an authority. What I am is VERY Skeptical in the face of an overwhelming lack of any evidence from a reliable third party having tested these products and come to some conclusions about what they really do and how effective they are. And yes some Mfgs do recommend a Weight Distributing Hitch for certain vehicles...NOT an Anti Sway system. They are two different things (but often combined into one product)

Sixth: I wish that we could depend on Trailer Life to put these things through a rigorous testing program with a reliable Auto testing Lab. But it will not happen in my view. To repeat what I said above; TL sells Tens of thousands of dollars in advertising space to the MFG's every year. Camping World sells them and installs them. Both companies are wholly owned subsidiaries of Good Sam Enterprises. They all have the same CEO (Marcus Lemonis) To expect this company to put public interest above their bottom line and piss off one of their major advertisers is...well frankly...naive. This is not to say that GSE is an evil company, I dont beleive that for a moment. But it is very mindful of who butters it's bread. So why take a chance on killing the Golden Goose so to speak. And this is admittedly not the largest advertiser or source of sales revenue for the company but it is SIGNIFICANT.

To the handcart question: The handcart or Dolly represents the Lever and the Inclined Plane. I will PM you on this. I was merely trying to find a way to better illustrate a part of physics that relates to this problem. My apologies if I offended you in any way it was not my intention.

Try to visualize this: take a toy tractor trailer, remove all of the friction that is present under the tires. Put your finger on the far back edge of the trailer and apply force (PUSH) sideways. What happens? The rear end of the tractor will move LATERALLY in the OPPOSITE direction. This is Newtons Third Law = For every action there is an opposite and equal reaction. This physical law is present in fifth wheels and Ball hitches. It is a lateral force.

BUT let me be very clear. This is not what INDUCES sway. This is the RESULT of sway.

What we need to concentrate on is WHAT CAUSES SWAY. My contention is that the forces that come to play are MOSTLY Driver induced. These products are a result of that driver behaviour and meant to counteract that. I further contend that if driven and loaded properly SWAY is not the huge Bogeyman that it is made out to be. And what we need is a system to train drivers not a mechanism that masks bad habits and that people believe is a SAFETY DEVICE.

[jmcgsd]

I'm late to this discussion, obviously but FWIW:

I tow a 7500# 27"6' TT with an old Ford F-350 Dually and there is absolutely no sway problems. As many have said if your TV is up the job and
Well matched to the load, sway control is probably not needed.

Years ago I towed a Coleman popup first with a Chevy S-10 and then with a Ford Bronco. Boy was sway control necessary on those setups! It was scary even with it. Never again.

[E_J_push_n_wind]

4X4Dodger wrote:
E&JPNW wrote: "Now place a 25' to 35' trailer with all of its weight and the lever it has between the center line of the axle assembly and the tongue coupler. I wish I knew how to place illistrations on here, I will try to paint a word picture. Picture an arrow pointing at the pivot point in a lateral fashon at both a 5th wheel hitch and a conventional hitch. This of course is latter force. Sure 5th wheel hitches have lateral force exerted against them. The difference is that because of its placement over the center line of the rear axle (or slightly forward of it) you lose the lever effect that a conventional hitch would exert against the TV because of its distance from the center line of the rear axle."

Answer:

I believe you are thinking in only one plane. The ball hitch is either equal to or BELOW the frame of the truck. this position is much more difficult to move the truck on a lateral plane than the 5th wheel.

I'm speaking in terms of through the length of the vehicle, not the height of the vehicle. You will be able to rock it in a "fish tail" motion. You will not be able to as effectively with a 5th wheel hitch.

I've got to ask the question, what are you thinking of when we use the term, "lateral force?" My understanding is, a force from the side in some fashion, again through the length of the vehicle on a horizontal plane. So yes, for the sake of our discussion I am thinking in only one plane as these are the forces exerted from a sway condition.

The 5th wheel is much higher ABOVE the frame with most of the trailer weight still above that to act as a lever against the 5th wheel and the frame. This equals a longer lever arm = more force. Thus you need that big plate of the 5th wheel to react out those forces down thru the frame.

In this picture, you are looking at this from a vertical plane, top down through the fifth wheel. I believe what you are describing is pitch. A vertical side to side leaning. If you are understand this to be sway, then I can certainly understand your dilemma as an anti sway device would certainly NOT not help in any way resolve this condition.

But this has little to do with TRAILER sway. What you are talking about would be the trailer swaying the TV. If the TV is doing its job and the rig is set up correctly that's not going to happen (except in extreme cases of out of control stops or similar)

Answer this simple physics question for me:

Tell me what two principals of Physics are represented by the HAND CART? (the two wheeled upright kind)

I don't ask this to embarrass you but to understand and hopefully show you that the physics you believe are reacting on the TV just aren't correct.

4X4Dodger, I'm not embarrassed. I've explained that I'm not an engineer and I'll add, neither a physicist. All due respect to you, I suspect neither are you, though I could be wrong. I think if you were, we would have a mathematical explanation of your hypothesis. I've seen/read comments on this forum from engineers and they are very descriptive in their scientific language and explanation of things. You and I are having a time of it trying to describe our point of view.

So.., I'll ask you to explain yourself with the hand cart principal and ask you how that applies to what we are talking about for me and the sake of other readers.

Think about this by looking at the design of most of these sway bar systems, they simply react out the forces of the trailer's side to side motion by exerting a countervailing force against the tongue. NOT THE TV. If your hypothesis were correct all that bar and chain mechanism that works against the trailer would be aimed FORWARD.

They work in unison on a lateral plain. At the risk of starting a fire storm, the premimum namely the HA and PP are designed so that the trailer CANNOT turn (sway) unless there is input from the TV. I invite you to look at the sticky in the travel trailer section on the HA and how it works. The other conventional hitches typically use friction of some sort to counteract a sway condition where the trailer is whipping side to side. Kind of like fish tailing in a manner of speaking. The difference between the conventional friction type is that friction can be overcome. With a PP or HA, if the hitch is in tension it shouldn't be able to. In theory the whole unit (TV & TT) would move as a unit.


E&J: "I'm not saying that there arent lateral forces on a fifth wheel hitch, I'm saying there isn't leverage in the same manner as a conventional hitch."

Answer: leverage is leverage it changes with the length of the lever. Not with the hitch type. If anything the 5th wheel is able to exert MORE leverage than the ball type.

Please explain? On a horizontal plane where a 5th wheel is able to exert more leverage? Am I missing something?

4X4Dodger, I've asked this question before and you still have yet to answer it. Please describe (on a horizontal pane) the leverage in relation to a 5th wheel hitch? I can't see it, unless I'm missing something. I've described I think quite clearly the leverage in relation to a conventional hitch on a horizontal plane. Unless we are on different terms (and I think we are), lateral to me is on a horizontal plane.

5th wheels are placed over the axles PRIMARILY for WEIGHT reasons. This takes advantage of the Carrying capacity of the P/u. There MAY be some advantages of stability (but not if the trailer is loaded wrong) but the reason 5th wheel travel trailers were designed in the first place was to provide a much bigger trailer (with a much higher tongue weight) to meet consumer demand for more space and amenities...it was not to reduce sway.

My conclusions from looking closely at these hitches and thinking deeply about the problem:

The VAST MAJORITY of sway problems are driver induced or improperly loaded trailers (same thing really)

Sway bars were a response to a lucrative market niche of the above that wanted to have a mechanism that damps out their inputs.

"Sway bars" better described as equalizing bars or weight distribution bars/spring bars. If your idea of these is as I suspect, then you have a misunderstanding of what the function of these bars are for. As I have just more accurately described them, the PRIMARY purpose for these bars was originally to distribute weight between the TV and TT. Over the course of the evolution of these spring bars sway control has been incorporated into the design.

More often than not, a 1 ton or even a 3/4 ton truck will not need these bars to tow a TT as they have sufficient suspension to "carry" the weight of a given TT. Reality is there are more 1/2 ton TV (P/U's and SUV's) on the road than their larger counterpart TV's. This is where the weight distribution are absolutely necessary to properly carry a said tongue weight. Without these spring bars it would be very unsafe to tow these trailers though it is done by unwitting folks.

Again, at the risk of starting a firestorm. The HA and PP hitches have sway control incorporated into the design of the hitch. you can tow without the spring bars and still have the added benefit of sway control (horizontal plane). Many (not all) of the friction type sway control conventional hitches NEED the spring bars as this is part of the source of friction.

While this product may have it's benefits under certain road conditions and driving conditions (driver input) They are NOT NECESSARY to haul a trailer safely.

If you have a 1 ton or in many cases 3/4 ton truck, I think you'd be hard pressed to get an argument. However, look in the owners manual of vehicles that are designed to tow in some capacity and they will state that you need a weight distribution hitch to tow weights greater than X. These hitches that you are adamant about not needing and blantantly stating are not a safety device is quite irresponsible IMHO. For someone to read this and view you as an "authority" (yep they are out there) puts them at risk and everyone around them.

We have two things that we are talking about. 1) anti sway device, and 2) (I bring up) weight distribution. While they are not necessarily one and the same, in many instances they are simply because this is how the MFG's have decided to make them. With a conventional hitch you can have one without the other, you have to know what you are getting. I will state that having a weight distribution hitch may be necessary depending on the TV and the trailer behind the TV. While it is good to have and can be a safety device, sway control may not be absolutely necessary. Again, this depends on a lot of factors including the size of the TV & TT, loading of TT, hitch arangement, driving conditions etc.

Dont expect Trailer Life or its editors to ever print a fair article on this subject as there is just too much money at stake. TL is owned by Good Sam Ent. and so is Camping World. A great deal of income is derived from the Advertising and sales of these hitches by the GS Enterprises companies.

Playing the devils advocate, do you have anything to substantiate your claim? While I'm sure they derive revenue from advertising, and perhaps sales, you make a pretty bold claim without any proof. You are accusing them of the very thing you are doing, making claims without any proof. Hitch sales, really?

Unless and until an independent third party similar to consumer reports does some real scientific testing on these products and draws a conclusion one way or the other I will remain a healthy skeptic.

To all of those that use them and believe in them this is certainly your prerogative. But I think you should exercise some care in claiming that they are a SAFETY device. I don't believe that has ever been proven...

And while your stories of roll-overs and radically swaying trailers are compelling they remain only ANECDOTAL evidence...without real investigation, rather than a lot of assumptions of what really happened.

But one of the most telling things for me is this. The people who owned my trailer before me used one of these hitches and it came with the trailer. I have never bothered to assemble it or use it and I have absolutely no sway problem with driving this trailer. In fact my first trip with this trailer was Chicago to Minot ND (over 1000 miles) during one of the worst wind and snow storms of the season...and NO SWAY. Much of the time roads were snow and ice covered and the wind blew as much as 40 MPH and more..

All due respect 4X4Dodger, what's the difference between your anecdotal story and another. Should yours carry more weight because you feel so strongly about it? Also, to your point about it not being proven. It hasn't been dis-proven either.

edited by author for clarity

[4X4Dodger]

E&JPNW wrote: "Now place a 25' to 35' trailer with all of its weight and the lever it has between the center line of the axle assembly and the tongue coupler. I wish I knew how to place illistrations on here, I will try to paint a word picture. Picture an arrow pointing at the pivot point in a lateral fashon at both a 5th wheel hitch and a conventional hitch. This of course is latter force. Sure 5th wheel hitches have lateral force exerted against them. The difference is that because of its placement over the center line of the rear axle (or slightly forward of it) you lose the lever effect that a conventional hitch would exert against the TV because of its distance from the center line of the rear axle."

Answer:

I believe you are thinking in only one plane. The ball hitch is either equal to or BELOW the frame of the truck. this position is much more difficult to move the truck on a lateral plane than the 5th wheel.

The 5th wheel is much higher ABOVE the frame with most of the trailer weight still above that to act as a lever against the 5th wheel and the frame. This equals a longer lever arm = more force. Thus you need that big plate of the 5th wheel to react out those forces down thru the frame.

But this has little to do with TRAILER sway. What you are talking about would be the trailer swaying the TV. If the TV is doing its job and the rig is set up correctly that's not going to happen (except in extreme cases of out of control stops or similar)

Answer this simple physics question for me:

Tell me what two principals of Physics are represented by the HAND CART? (the two wheeled upright kind)

I don't ask this to embarrass you but to understand and hopefully show you that the physics you believe are reacting on the TV just aren't correct.

Think about this by looking at the design of most of these sway bar systems, they simply react out the forces of the trailer's side to side motion by exerting a countervailing force against the tongue. NOT THE TV. If your hypothesis were correct all that bar and chain mechanism that works against the trailer would be aimed FORWARD.


E&J: "I'm not saying that there arent lateral forces on a fifth wheel hitch, I'm saying there isn't leverage in the same manner as a conventional hitch."

Answer: leverage is leverage it changes with the length of the lever. Not with the hitch type. If anything the 5th wheel is able to exert MORE leverage than the ball type.

5th wheels are placed over the axles PRIMARILY for WEIGHT reasons. This takes advantage of the Carrying capacity of the P/u. There MAY be some advantages of stability (but not if the trailer is loaded wrong) but the reason 5th wheel travel trailers were designed in the first place was to provide a much bigger trailer (with a much higher tongue weight) to meet consumer demand for more space and amenities...it was not to reduce sway.

My conclusions from looking closely at these hitches and thinking deeply about the problem:

The VAST MAJORITY of sway problems are driver induced or improperly loaded trailers (same thing really)

Sway bars were a response to a lucrative market niche of the above that wanted to have a mechanism that damps out their inputs.

While this product may have it's benefits under certain road conditions and driving conditions (driver input) They are NOT NECESSARY to haul a trailer safely.

Dont expect Trailer Life or its editors to ever print a fair article on this subject as there is just too much money at stake. TL is owned by Good Sam Ent. and so is Camping World. A great deal of income is derived from the Advertising and sales of these hitches by the GS Enterprises companies.

Unless and until an independent third party similar to consumer reports does some real scientific testing on these products and draws a conclusion one way or the other I will remain a healthy skeptic.

To all of those that use them and believe in them this is certainly your prerogative. But I think you should exercise some care in claiming that they are a SAFETY device. I don't believe that has ever been proven...

And while your stories of roll-overs and radically swaying trailers are compelling they remain only ANECDOTAL evidence...without real investigation, rather than a lot of assumptions of what really happened.

But one of the most telling things for me is this. The people who owned my trailer before me used one of these hitches and it came with the trailer. I have never bothered to assemble it or use it and I have absolutely no sway problem with driving this trailer. In fact my first trip with this trailer was Chicago to Minot ND (over 1000 miles) during one of the worst wind and snow storms of the season...and NO SWAY. Much of the time roads were snow and ice covered and the wind blew as much as 40 MPH and more...

edited by author for clarity

[E_J_push_n_wind]

4X4Dodger wrote:
E&J Pushnwind:

I am not sure why you think there is no lateral force on a fifth wheel. There certainly are..in fact because there is a round pin that fits into the fifth wheel you can say that there are forces at any given time in almost any direction of the compass.

I'm not saying that there arent lateral forces on a fifth wheel hitch, I'm saying there isn't leverage in the same manner as a conventional hitch.


Your point about car carriers is not really complete. The STINGER type of fifth wheel arrangement you see on Auto carriers has all the same forces as any other. However it does exert different leverage upon the Tractor.

My point exactly, because it is aft of the center line of the rear axle assembly. This is where the lever is and the center line of the rear axle assembly is the fulcrum point.

As for wind and auto carriers I am afraid that you have overstated the case somewhat. When an auto carrier is loaded about 75-80% of the area on the side is blocked by cars and trailer structure meaning that side winds can affect them quite a bit. Add to that the fact that the cars on top will sway on their own due to being on their suspensions means there is an added lever arm way up high oscillating at a different rate than the trailer making things even worse.

But to cut to the chase here. The ball type hitch is a proven design that has worked well for many many years. There is nothing wrong with it. A 5th wheel has some advantages but only if the design of the hitch and the plate and pin on the trailer are up to the job (not always the case) The same forces are present no matter which hitch you are using. HOW those forces are transmitted to the TV is different.

The distance from the average p/u truck rear axle to the ball hitch pivot point is so close as to be mathematically insignificant in thinking about which forces are the most likely to cause sway. SIDE WINDS in and of themselves are not the cause of sway...it is the driver CORRECTION that causes the sway.

All due respect 4X4Dodger, this is where I strongly disagree with you. You make somewhat of a blanket statement. I know you stated pickup truck but everybody is not towing with a pickup truck and that overhang will vary from MFG. to MFG. and in that, from vehicle to vehicle.

I stated earlier that I am no engineer so I can't show you the math however I ask the question. How long does a lever need to be to be effective? Follow me if you will. Lets say that you have 36" from the hitch ball to the center line of the TV rear axle. You can grab that hitch ball with your hand and begin to rock the TV from side (on a lateral plane), with each push and pull you will get a little more movement with each "rocking" so to speak. Now if you will place a pin of some sort into a 5th wheel hitch and attempt to do the same thing. If you were able to grab hold of it, you wouldn't be very effective in moving the TV because of the placement of the hitch over the center line of the axle.

Now place a 25' to 35' trailer with all of its weight and the lever it has between the center line of the axle assembly and the tongue coupler. I wish I knew how to place illistrations on here, I will try to paint a word picture. Picture an arrow pointing at the pivot point in a latteral fashon at both a 5th wheel hitch and a conventional hitch. This of course is latter force. Sure 5th wheel hitches have lateral force exerted against them. The difference is that because of its placement over the center line of the rear axle (or slightly forward of it) you lose the lever effect that a conventional hitch would exert against the TV because of its distance from the center line of the rear axle.

Lastly, a sway control works for a conventional hitch because it counters leverage. It is able to meerly because of the fact that there is a lever to work against, length of hitch and the center line of the rear axle being the fulcrum point. Again, I ask the question. Where is the "lever" with a 5th wheel hitch? I'll say again, where there is no lever, there is no leverage. How can there be?



As for passing vehicles. Tractor trailers pass me all the time when I am towing my 30ft tt. It doesnt move.

My guess is that some drivers, slightly spooked by that huge truck and its Air Wake zooming by them instinctively let off the accelerator pressure and/or make a sudden move to the right side. THIS is SURE to cause sway as the Big Truck goes by.

As for your analogy of the boat wake...It's not completely accurate. If you look at what really happens to the air there is a period of force as the air wake hits and then a SUCTION as the truck goes by.

When your trailer is going down the road there is a similar wake coming off the front as it passes thru the air. this air pushes out from the side of the trailer near the front and comes back at some point to slide along the side of the trailer. For all intents and purposes this air flow is even on both sides. therefore it isnt really a cause of sway.

I agree with you partially on this point, however the initial wake that "brakes off" the front is commonly called a bow wave. That bow wave that is created from motor coaches, semi's, large vans and yes our TT's is what affects other vehicles as they or we pass by. That bow wave is what "upsets" or may cause that harmonic oscillation we spoke about earlier. The vaccume or airmovement along the sides of our trailers as we pull them down the highway does not affect us while we are moving down the road. I was never refering to that air movement but rather the air movement caused by similarly large vehicles as they pass us.

However when you have a dramatic rear overhang as some trailers and RV's do this does present a lever arm for a greater amount of air to hit behind the trailer axles on one side or the other.

Remember, as passing semi's and motor coaches reach the rear of your TT that bow wave will begin to push against the back (overhang) of your TT. As that bow wave passes the center line of your TT it will still be pushing against the side of your TT only as it passes the axle assembly the force is in the opposite direction. That is where the harmonic oscillation may begin.

The best way to avoid this unequal force is to keep a steady acceleration on when being passed by any larger vehicle.

[4X4Dodger]

E&J Pushnwind:

I am not sure why you think there is no lateral force on a fifth wheel. There certainly are..in fact because there is a round pin that fits into the fifth wheel you can say that there are forces at any given time in almost any direction of the compass.

Your point about car carriers is not really complete. The STINGER type of fifth wheel arrangement you see on Auto carriers has all the same forces as any other. However it does exert different leverage upon the Tractor.

As for wind and auto carriers I am afraid that you have overstated the case somewhat. When an auto carrier is loaded about 75-80% of the area on the side is blocked by cars and trailer structure meaning that side winds can affect them quite a bit. Add to that the fact that the cars on top will sway on their own due to being on their suspensions means there is an added lever arm way up high oscillating at a different rate than the trailer making things even worse.

But to cut to the chase here. The ball type hitch is a proven design that has worked well for many many years. There is nothing wrong with it. A 5th wheel has some advantages but only if the design of the hitch and the plate and pin on the trailer are up to the job (not always the case) The same forces are present no matter which hitch you are using. HOW those forces are transmitted to the TV is different.

The distance from the average p/u truck rear axle to the ball hitch pivot point is so close as to be mathematically insignificant in thinking about which forces are the most likely to cause sway. SIDE WINDS in and of themselves are not the cause of sway...it is the driver CORRECTION that causes the sway.

As for passing vehicles. Tractor trailers pass me all the time when I am towing my 30ft tt. It doesnt move.

My guess is that some drivers, slightly spooked by that huge truck and its Air Wake zooming by them instinctively let off the accelerator pressure and/or make a sudden move to the right side. THIS is SURE to cause sway as the Big Truck goes by.

As for your analogy of the boat wake...It's not completely accurate. If you look at what really happens to the air there is a period of force as the air wake hits and then a SUCTION as the truck goes by.

When your trailer is going down the road there is a similar wake coming off the front as it passes thru the air. this air pushes out from the side of the trailer near the front and comes back at some point to slide along the side of the trailer. For all intents and purposes this air flow is even on both sides. therefore it isnt really a cause of sway.

However when you have a dramatic rear overhang as some trailers and RV's do this does present a lever arm for a greater amount of air to hit behind the trailer axles on one side or the other.

The best way to avoid this unequal force is to keep a steady acceleration on when being passed by any larger vehicle.

[JIMNLIN]

Having pulled heavy GN/bumper pull/5th wheel and pintle trailers for a living I found the size of the tow vehicle makes no difference if the rig has the tail wagging the dog issues. Its not just a matter of drivers experience or too small of a tow vehicle.
I've seen 40' pintle hitch enclosed vans (axles in the center like our RVs) behind single axle class 8 tractors or my one ton DRW trucks with severe sway issues.
The 40' enclosed trailer/pintle hitch I had in service was bitzh to pull with any of the trucks we had. Myself and my drivers hated to have to be the one who had to move it to the next job site.
A class 8 tractor pulling semi trailer/trailer have nothing in common with a bumper pull TT as in the case of this discussion with the axles in the center of the box and the ball on the tow vehicle extended well behind the tow vehicles bumper. IMO a poor choice for comparing or as a example.

I don't use a anti sway device but I've been around long enough to know there are lots combos out here that needs them. Every one doesn't own the equipment you or I own so making a claim a anti sway devise isn't needed isn't the way the real world operates.

[E_J_push_n_wind]

4X4Dodger wrote:

E&J push'n wind wrote:

4X4Dodger wrote:
Let me clarify that when I wrote about the distance between the pivot point and the AXLES I mean the TRAILER axles NOT the tow vehicle axles. It is this distance that truly affects how a trailer tows. I question whether the distance from pivot to TV axle has any great affect at all. This is a weight issue.

One reason that the axle distance matters is overhang on the rear. The greater the overhang beyond the rear axles the more the Airflow works against the sides of the trailer...with a longer lever arm than if the axles were farther to the rear. This would cause sway.

Lets use your example. Lets place the wheels on the trailer all the way at the rear like on a tractor trailer combo. Looking at the pivot point on a 5th wheel trailer and a conventional hitch or a pintle hitch. Now lets place lateral force against the pivot point on the 5th wheel hitch and lateral force at the pivot point on the conventional hitch. That wind force that you speek of works forward of the trailer axles as well. Difference is with a 5th wheel hitch, that leverage I spoke of earlier doesn't have as great an effect on the pivot point on the 5th wheel hitch as it does on the conventional merely because there is virtually no leverage at the pivot point because the pivot point on a 5th wheel hitch is directly over the center line of the rear axle. With a conventional hitch that force exerted by the wind forward of the axle (on TT) has a compound effect because of the leverage created by the distance of the pivot point behind the rear axle (on TV).

Now, if you will. Move the trailer axles to about 2/3 the distance form the pivot point like on many TT's. That wind again that you spoke of has a multiple effect in that it works against you in one direction as a passing vehicle begins to pass and pushes against the back of the trailer aft of the center line of the axles. As the passing vehicle reaches the trailer axle center line it begins to work in the opposite direction as it continues to push against the side of the trailer, once past the axles, that push is opposite it was before it "crossed" the center line of the trailer axles. This is where "sway" begins to occur. Again only because of the leverage created by the distance of the pivot point behind the center line of the rear axle of the TV.

That lateral force is eliminated with a 5th wheel hitch setup. The placement of the hitch directly over the center line of the TV rear axle makes it so that there is absolutely no leverage on the TV. Not so with a conventional hitch, again.., that lateral force against the hitch is working against the TV in as much as it has leverage to move the TV by the later force working against the hitch. The longer the distance behind the center line of the rear axle of the TV the greater the leverage. Can you see it? I hope I was able to explain what I am trying to get across.

Now with the traditional friction sway control, if the friction is overcome problems can begin. With the "premium" hitches (and this is where the firestorm begins) the pivot point is "changed." I'm not an engineer so I can't and wont attempt to explain the math. The only one I can explain is the Pull Right where the pivot point is literally and physically moved forward to the center line of the rear axle (or as near as possible).

Either way, tested by an independent organization or not. You can't ignore the physics of it. With the friction type of control, if you make it "harder" for the trailer to pivot. It accomplishes what it designed to do, create tension so as not to allow it to pivot so easily. With the "engineered" type, the possibility of sway is engineered out.

The question you ask about it masking a bad setup. I'm sure beyond a doubt that there are setups out there like that where someone maybe happy as a lark (with there sway control) all the while they are a ticking time bomb. I am equally sure that there are folks out there that need a sway control of some type (and are without) that are an accident waiting to happen. And there are those that have it that perhaps don't need it and so on and so forth. You get the idea!

I was speaking of AIRFLOW along the side of the trailer and didnt make that clear I am afraid.

You are right however that a force = wind from the SIDE, MAY have the effect you say IF it was localized, which it isnt. It tends to be fairly evenly spread over the entire side. This should not cause the sway you might think. However it would tend to RESULT in sway as the driver tries to compensate for the force of the wind.

Truth be told, the wind force developed from a passing vehicle looks very much like the wake developed in the water from a boat. Some of difference is that it is not only on a “flat plain” as on the surface of water but rather is reflected by the height of the vehicle as well as the speed of the passing vehicle. We’ve all felt that wake as semi’s passing us while we are standing still. Whether we are in a solo automobile or van or pickem up or what have you. It is not “evenly spread out along the entire side of the trailer” as you say, by a passing vehicle (semi or motor coach or any other vehicle for that matter). I would agree with you that this in and of itself may not necessarily be the cause of sway but it could be the cause of that “Harmonic Oscillation” rather. I would also agree that it might be aggravated by driver input.

I had an occasion to experience a “mild” sway condition on one occasion when towing a small single axle utility trailer that was clearly overloaded. I was in the slow lane taking it easy when the trailer began to oscillate, mildly mind you but it got my attention none the less. The trailer had no brakes and I know about accelerating to attempt to alieve the conditions. Problem was I was already going faster than I would like to have been going and speeding up I’m sure while it may have momentarily cured it, I believe ultimately it would have gotten worse as I believe it was the speed itself that contributed to the oscillation. I knew better than to hit the brakes as this would have been disastrous as well. I gently eased off of the throttle and prayed. Thankfully it worked its way out and I kept my speed much lower after that.


To claim as you do that in a fifth wheel set up there is "NO LEVERAGE" by the trailer on the tow vehicle is a misunderstanding of the physics. There is significant leverage. Leverage = force; There are forward, rearward and side (lateral) forces as well as Yaw forces put on that fifth wheel. There is also friction between the surfaces (even greased) that play into this. A simple example of the forces upon your fifth wheel: drop one side of your trailer axle into a low ditch; the forces on your fifth wheel may be enough to loft your opposite rear TV axle OFF the ground. This is an extreme example but it clearly illustrates the forces at work. The other extreme example of forces on the fifth wheel is jackknifing. Being over the TV axles may help stability but it DOES NOT eliminate the forces involved.

Please do not misunderstand what I mean when I say that there is no leverage on a 5th wheel setup. The examples of the forces you describe are understood and are a given. The same forces are exhibited on a conventional hitch as well with perhaps yaw as an exception (provided hitch is setup without sway control as this can effect yaw in a conventional hitch with spring bars attached depending on the type of hitch). Where you say ”leverage = force,” force that would be created by a lever. In this case, where there is no lever, there is no leverage. What I mean by leverage is that there is no (virtually if you will) lateral “leverage” on the pivot point of the tow vehicle with a 5th wheel setup in the same way as a conventional hitch. The word leverage implies that there is a lever. Again, if you’ll be intellectually honest, the length of the overhang behind the centerline of the TV axle plus the length of the hitch itself will absolutely affect how the TV responds to lateral forces placed against the pivot point. Again, not so with a 5th wheel hitch.as there is no point of leverage. With a conventional hitch, the center line of the rear axle of the TV becomes the fulcrum point. Where is the fulcrum point with a 5th wheel hitch setup? The only 5th wheel hitch setup that I can think of where this could come into play is an auto transporter where the 5th wheel hitch is placed aft of the center line of the TV axle. I really can’t see this as a problem though because the lateral forces placed on a hitch pivot point are usually caused by wind. Auto transporters are usually open and “airy,” not affected by blowing wind

The REAL issue is WHY is the trailer swaying in the first place. Is it driver induced sway? Improper design of axle placement vs trailer weight? or a TV that is less that 1/3rd the overall weight of the fully loaded trailer? If sway is induced by weather conditions or being passed it is often made worse by driver response (reflexively slowing or braking when in fact a slight acceleration is the right move and will usually result in the sway disappearing fast)

If the sway is DESIGN induced this can probably be fixed with different loading in some cases. (of the trailer) or a different TV.

BTW: most tractor trailers do not keep their axles all the way rearward this overloads the Drive axles and may not be legal in some states due to "bridge" laws. Where having the axles all the way to the rear really helps you is in parking in reverse in very tight spots. This allows the trailer to pivot at the far rear end and it can be spotted very precisely. I know to some this may sound counter intuitive but it's true.

[4X4Dodger]

you think you have sway problems....

This kind of thing is common...gee do you think he needs a 3/4 Pick up?

[Caveman_Charlie]

4X4Dodger wrote:
Cavemanchaerlie wrote: "Just by the description it sounds like driver in put make the problem worse however it got started. Back when we used to pull a lot of bumper hitch livestock trailers on the farm if a sway problem got started it was easily stopped by reaching down and activating the trailer breaks. This straighten it right out. The only time that happened is if the livestock were moving around in the trailer."


This is true and a good way to stop the sway. But it is the same thing as accelerating the TV (in physical terms)

Yup, my dad used to say something like "You got to tow the trailer and not let it push you".

[4X4Dodger]

After reading so many of the replies to this question it has occurred to me that some percentage of "The Sway Problem" has to do with the Drivers misunderstanding or not understanding the Physics involved in pulling a trailer.

[4X4Dodger]

Cavemanchaerlie wrote: "Just by the description it sounds like driver in put make the problem worse however it got started. Back when we used to pull a lot of bumper hitch livestock trailers on the farm if a sway problem got started it was easily stopped by reaching down and activating the trailer breaks. This straighten it right out. The only time that happened is if the livestock were moving around in the trailer."


This is true and a good way to stop the sway. But it is the same thing as accelerating the TV (in physical terms)

[Caveman_Charlie]

4X4Dodger wrote:

mosseater wrote:
I read through the entire post. There's a lot of doubters, a lot of specualtion. What I didn't see until the previous post was anybody who had seen or dealt with real sway. Not being blown around or pulled by road joints, or even emergency manuevers. Real sway. I have seen it. And it's ugly.

It won't matter how good your skills are or how big your rig is if it happens. It's the perfect storm, and you're lucky if you end up with the rubber side down. You won't have time to do much thinking. The rig I saw was an F-150 longbed hauling a small (4000 lb?) excavator at about 30 mph. It started gradually and quickly crescendoed to an all-out "S" festival, which had the wheels of the truck and trailer both off the ground almost a foot. It started by itself and ended when it was done. It was clear the driver was along for the ride. Period.

I know most of you will blow this off. That's fine, the choice is yours. All I can say is the anti-sway systems on the road will hopefully allow a margin of control to exist which might allow you to regain the composure of your rig if it ever happens. Whatever else a WD/anti-sway system might or might no do safety-wise, I can't really say. I haven't seen credible testing that absulutely puts the issue to rest. I can say that what most people think is "sway"....isn't. If you ever get a chance to see it or experience it, you will be astounded. It almost seems supernatural to observe.

First of all with all due respect NOTHING happens in a vacumn. That sway was INDUCED by some force acting on the trailer or TV or both. Most likely, in the absence of any other obvious sources, it was driver induced.

The trailer and load you describe are problematic and often loaded incorrectly. Or possibly OVERLOADED.

Once the sway begins if the driver slows, the sway motion will increase. If it gets to the point you describe it is VERY difficult to recover. The forces involved tend to reach a point of Harmonic Oscillation which will continue to increase until it is interrupted by other forces.

But no matter what. There was a PHYSICAL reason for this,it did not happen "all by itself" and My bet is that if investigated carefully it would be found that it was a result of improper loading and driver input.

It is scary to see but I am not sure that is a reason to be sold on a sway bar system. NOTHING can replace learning to LOAD it and DRIVE it properly.

Just by the description it sounds like driver in put make the problem worse however it got started. Back when we used to pull a lot of bumper hitch livestock trailers on the farm if a sway problem got started it was easily stopped by reaching down and activating the trailer breaks. This straighten it right out. The only time that happened is if the livestock were moving around in the trailer.