trailer sway control

Trailer Sway Control In Travel Trailers

The first thing I want to show you is why sway happens. I am explaining how sway affects towing, how it affects a travel trailer, and the things you can do as well as how trailer sway control work.
I see people writing in the comments and asking out which is the best weight distribution hitch to buy, but they do not know which is the best trailer sway control system that they should implement according to their towing vehicle and travel trailer, before deciding which is the most suitable weight distribution hitch.
So I will first explain the main features of trailer sway control and what forces are at play on their travel trailer while they are driving down the road. What causes sway in the first place, is what you really have to understand.

Causes of Sway: Wind And The Pull And Push Vortex

Consider why is sway more pronounced on something like a travel trailer versus a boat, or a gooseneck trailer, or a flat utility trailer, and the real answer to that is wind and a larger exposition surface in the trailer what increments the pull and push vortex.
The fact is that a travel trailer carries a much higher profile to it, generally anywhere between 8 and 13 feet tall, and because it is so much taller the forces at play when wind is hitting the side of it make it react like a wall or a kite because of the push and pull vortex explained. Very similar effect if you are ever throwing away a big cardboard box and it is windy outside.

Causes of Sway: Alignment of Tires

Now another thing that a lot of people does not realize that can cause sway are the tires.  If the tires on your travel trailer are not aligned properly and they are not pointing perfectly straight, that is going to induce sway.
Consider the situation where your tires are curved out slightly. Here the vehicle will start wandering off because the tires are not pointed perfectly straight. What is going to happen, is that the truck will counteract this effect by pulling it back. This in turn will create an imbalance in the front of the trailer which will cause the trailer to start moving side to side.
I am sure many of you have seen in the road people pulling travel trailers with cars, where it looks like the trailers are dangerously moving sidewards. Even, most You Tube videos of RV accidents are happening due to the excess of sway and lack of a trailer sway control system in place. Much of that sway has to do with the fact that the alignment of the tires on the trailer is causing the front of the trailer to move back and forth. This is because as the trailer wants to go a different direction than the vehicle, the vehicle is constantly pulling it straight.

Causes Of Sway: Improper Weight Distribution

So the wind is not the only thing that can cause sway even though it is a main contributor to it. Definitely unaligned tires can be a huge contributor to sway as well.
Furthermore, there is another aspect that can enhance sway. This is an improper weight distribution on the towing vehicle, and too little tongue weight. We have this article to explain in detail what is tongue weight, and why sway can be caused by too little tongue weight.
You need in these cases a proper approach that translates into an adequate weight distribution system that includes this trailer sway control. Basically you just want the vehicle to ride level and you do not want to pull too much weight off of the front or pull too much weight off of the back if your hitch is improperly setup.
Now the easiest way to explain how a travel trailer will affect a towing vehicle is to understand where sway occurs. Sway takes place between the back portion of the pickup truck and the front portion of the travel trailer. The main reason it is occurring is because that connection point that is the trailer hitch is essentially a hinge and tis affected by all the forces at play: wind, pull and push vortex, improperly align tires, inadequate tongue weight, all sorts of different things.
Most weight distribution systems on the market with trailer sway control attempt to counter these effects with friction. There are aftermarket add-ons for weight distribution hitches as well as weight distribution hitches with integrated trailer sway control.
What actually the weight distribution hitch is doing, with trailer sway control, is creating two symmetrical pressure points, one on each side of the hinge, acting almost like two straight bars that are connecting the back of the truck to the front of the trailer. Therefore, it is incapable of sidewards motion or at least it is much less.
Some of the most effective trailer sway control systems out there apply a tremendous amount of pressure downwards on pads or L brackets on the travel trailer to really keep it from moving side-to-side. Some of the most complex trailer sway control systems like for example the Hensley hitch actually eliminate the hinge. There is no more hinge there and it creates a system that does not rely on a typical single point turning mechanism. Therefore, you are eliminating that hinge effect as the Hensley hitch has changed the role of the traditional hinge in the trailer sway control discipline.
trailer sway control

Longer Wheelbase And The Effect On Sway Control

Likewise, the next question people will ask is that they have heard that having a longer wheelbase, (understanding wheelbase as the segment line that marks the distance between the center of the front wheel and the center of the rear wheel) can help eliminate sway. Well, it does not necessarily eliminate sway, but it can help reduce it significantly, provided that you also have a decent trailer sway control implemented.
The reason why having a longer wheelbase truck inherently is going to change the dynamics of towing is because you are extending the overall space between the tires and because of that it takes more leverage for the trailer to actually impact the truck and the truck has a better ability of straightening out the trailer just by natural motion.
As I was explaining, a longer wheelbase vehicle is inherently providing you a little bit of additional trailer sway control. Now, this improvement alone, is not going to defeat sway and will become the definitive trailer sway control system. By getting an 8-foot bed, this does not automatically mean that you will eliminate completely sway, but take it as an additional enhancement to trailer sway control by marginally reducing sway.

Trailer Sway Control In a Fifth Wheel Versus A Travel Trailer

Now we can analyze how trailer sway control behaves in a fifth wheel versus a travel trailer. Which is the difference between them, not in terms of weight, floorplan, or price, as we have other articles to deal with those differences between them. We will study these RV classes now regarding weight distribution, trailer sway control, and effort required to tow them safely.
In fifth wheel towing, as we know, the hitch essentially moves moved to the center point of the truck itself in the bed of the truck, using a gooseneck hitch. To see how this works, we have dedicated articles about pros and cons of fifth wheels, and gooseneck hitches.
The hinge has been been moved from the back of the truck affecting the rear stability of the towing vehicle to over the center point of the axles in the bed of the truck, so you can
technically still have sway if the wind is strong enough. But the reason why there will not really be any sway is because you no longer have the ability to fold that hinge like you would with a travel trailer.
The tires themselves are always going to be the traction point holding the truck down and because those tires are gripping the road, you are essentially creating a point to where if wind hits this the center point where your kingpin would be is putting pressure directly against the side of the tires of the truck. Thus, the truck itself just does not have the ability to move side to side as if you had the leverage focused on the back point of the bumper here causing the truck to sway.
As we can notice from these statements above, in a fifth wheel, there is almost no sway at all. You would rarely encounter a situation unless it is just incredibly windy where you would feel kind of that instability caused by that wind.
Fifth wheels over kingpin are definitely the safer as well as the least stressful way of towing because as I indicated in the text above, it move the pin weight over the rear axle as opposed to behind the rear bumper.
You do not have to worry about weight distribution and trailer sway control practices nearly as much either, simply because you do not have that leverage point behind the tires that
essentially want to remove weight from the front but for the most part, it is simply going to affect rear payload and it is not going to have much of effect on the front of the truck.
Using a system like this with airbags where you can level the vehicle back out is definitely
the better setup. As aforementioned it is very difficult and unlikely to have sway in a vehicle like this. You will not need a weight distribution hitch or any trailer sway control device.

Traction Effect As An Influence To Sway Control

Where tires make contact to the road is traction, and where there is essentially no force on the road so naturally anywhere underneath the middle point of the trailer where nothing is touching the ground to the nose of the travel trailer, there is nothing to keep it stuck to the ground as there are no wheels and therefore no traction points.
A fifth wheel helps to counteract that lack of traction in some areas, simply because your traction point, hence the point that is actually making contact with the ground and being pulled down by gravity is the rear axle of the towing vehicle.
Therefore, this makes the entire unit, a single unified convoy of towing vehicle plus fifth wheel. When you start to turn because your pivot point is over the axle, it is not going to act the same way as a travel trailer would act,  because you no longer have the leverage working against the back of the truck.
In the travel trailer, there is no traction in the hinge at all. There you simply have the
connection between their rear bumper of the truck or the hitch and the trailer so the traction in turn that you are trying to use with a trailer sway control hitch are those friction bars that connect the two vehicles together and keep the whole convoy unit rigid. So the mechanism of trailer sway control is we can say, relying on friction here to make the truck and the travel trailer essentially act as one unit.
With an adequate trailer sway control, when the wind or a vortex generated by passing trucks hit the side of the trailer, instead of moving sidewards, you have the bars that are creating essentially a rigid connection. This double bar trailer sway control will not allow the entire unit to move side to side

Best Trailer Sway Control System

  • The Hensley hitch is the best trailer sway control system. The pro is that it eliminates sway and the cons are the price and all the tongue weight it adds to the equation, as it is very heavy.
Therefore, the best ways you can naturally implement a proper trailer sway control is to go to a convenient but expensive weight distribution hitch like a Hensley hitch, which essentially eliminates way it adds a lot of weight to the back of your truck and a lot of
weight to the tongue of your trailer, known as tongue weight or nose weight.
As this hensley hitch adds so much tongue weight because it is very heavy, you must ensure that you have the payload capacity to support such a hitch even if it adds so much improvement to your trailer sway control.

Trailer Sway Control: Conclusions

First conclusion, is that you can eliminate sway with a Hensley hitch that is currently the most advanced approach to trailer sway control.
Otherwise, another solution is to buy a fifth wheel instead of a travel trailer. Towing with a fifth wheel instead, will almost always eliminate sway as well as going with a very high quality weight distribution hitch.  Furthermore, importantly, making sure that your weight distribution system along with trailer sway control hitch is set up properly.
If this trailer sway control hitch is instead not setup adequately, if the bars that are designed to create friction on those L brackets aren’t resting perfectly flat against the surface of the L bracket or, likewise, if you do not have the right amount of force being applied to those bars to really prevent the two from pivoting, you are not really doing anything to improve your trailer sway control, you are not having any effect on controlling this way.
The key to utilize a weight distribution system and likewise a trailer sway control system, is ensuring that it is set up perfectly and I really mean that you do not have a lot of margin
for error when you are setting up your trailer sway control.
So, you really need to ensure that you setup the trailer sway control as close to perfect as possible to get the most out of it even being off by a few degrees angle off of your L bracket. can really cause a system to be pretty much ineffective. The whole point of the
trailer sway control is to create a rigid connection between the truck and the trailer.
Even when you make a turn while driving, you will hear that the trailer sway control makes some noise. Like a scraping noise to be more precise, and that is simply because the trailer sway control system is trying to counter that turn as it counters sway. It is basically trying
to do exactly what it does: to counteract sway but during a turn. Anyway, you will be allowed to turn.
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Alexander Beliavski
I am Alex, an RV designer and RV developer. I create bill of materials for RV manufacturers for travel trailers and fifth wheels. I have also worked as an RV designer, As a consultant, I create customization trees for RV manufacturers who want to offer a solution to prospective customers to design their custom RV with variant configuration. I sell in Indiana trailer hitches, hitch balls, goosenecks and weight distribution systems and I provide advice to customers who want to know which is their towing capacity, which hitch ball should they utilize and how to deploy a weight distribution system. I do my best to explain all these processes and their installation, here in RV Favorites.