• November 14, 2021

Trailer sway 101

Yaw, more commonly known as rocking in the RV industry, is a dirty word for trailer owners. The definition of yaw or roll is a side-to-side movement. Nothing will ruin the way you feel about camping faster than the first time you experience trailer sway.

You’ve camped in a tent for years and now you decide it’s time to move on to a pop-up window. Go to your local dealership and find a pop-up with the perfect floor plan for you and your family. The seller knows that it will be close to the maximum weight that his vehicle can tow. You really need a sale because things have been slow. Rather than risk losing the sale, you decide not to explain the added expense of proper hitch work to safely tow your new trailer.

Everything is ready for a weekend getaway. You’ve done all your pre-trip checks and you’re good to go. Load the most precious cargo you have, your family, in your tow vehicle and embark on a new adventure. Everything is fine when you leave home. Take the entrance ramp to the interstate. You are cruising at the speed limit enjoying the music from the radio. Suddenly, out of nowhere, a transfer truck driving twenty miles over the speed limit passes you like you’re sitting still. The pop-up window is fed into the draft created by the truck. In an attempt to correct this totally unexpected event, you oversteer and the trailer begins to go in the opposite direction. Not quite sure what to do, she slammed on the brakes and turned the steering wheel to the left and then to the right. Now that one-ton trailer behind your sport utility vehicle is swerving from side to side and starting to affect what little control you have over the vehicle. The results are catastrophic.

Ok, since this is just an article, let’s start over and fix this before you realize there is a potential problem. You bought your pop-up from a reputable local RV dealership. At the risk of losing the sale, your salesperson explains that you will need specialized hitching work to safely tow your new trailer. You’re a bit skeptical, and you feel like they just want more of your money. Besides, your father never needed any of this. He just hooked the trailer to the ball and left.

Decide to give the salesperson the benefit of the doubt and listen for a minute. He shows you in his book that his tow vehicle is rated to tow a maximum of 3,500 pounds. It then explains what you need to consider for that trailer classification. It includes the weight of your new caravan, any aftermarket accessories, such as the roof-mounted air conditioner and battery that the dealer will install, all cargo and personal belongings you load on the trailer and tow vehicle, and the weight of passengers in the vehicle. Now all of a sudden the salesperson has your full attention. You had no idea that all of this had to be considered.

He shows you the weight tag on his new trailer. Unloaded Vehicle Weight (UVW) is 2,100 pounds. The air conditioner weighs 100 pounds and the deep cycle battery weighs 50 pounds. To be safe, he estimates that you will carry around 300 pounds of cargo and then add another 300 pounds for your wife and two children. You are amazed at how quickly things pile up.

You are now 2,850 pounds instead of the 2,100 pounds you thought. It is not over yet. Your salesperson begins by explaining that each state has different requirements for how much a trailer can weigh before it requires trailer brakes. In your state, the weight is 3,000 pounds, but your dealer has brakes installed on any trailer they ask to weigh more than 2,000 pounds. He explains that even though his vehicle is rated to tow 3,500 pounds, the vehicle’s brakes were designed to safely stop the weight of the vehicle, without dragging an additional ton and a half behind it.

He takes him to the parts department and shows him a brake controller and explains that this is what activates the trailer brakes and that the dealer will install it when they do the trailer light wiring. You like the features you explained about the brake controller. The fact that you can manually adjust the amount of braking action so that when you step on the brake pedal, the tow vehicle and trailer work together to stop the weight in a reasonable amount of time. What you really like is the part you explained about the manual override lever that engages the trailer brakes without using the vehicle’s brakes.

He said if you’re on a steep grade and you don’t want to prematurely wear the vehicle’s brakes, slowly slide the lever and the trailer brakes will slow you down. But what really convinced you was when he explained that if the trailer starts to sway, you can gently move the lever, activating the trailer brakes, to help straighten the trailer. He went on to explain that trailer sway is one of the biggest potential problems you can encounter when towing a trailer. List some of the factors that contribute to trailer sway.

o First, poor trailer design contributes to trailer sway. When there is too much weight behind the trailer axles, making the tongue weight less than 10% of the trailer’s weight, it has a natural tendency to sway.

o Incorrect tire inflation

o Improper weight distribution hitch settings

o No sway control on trailer

o Crosswinds

o A transfer truck that goes through the back of the trailer.

o Descending slopes

o Tow speeds

o Tow vehicle that does not adapt properly to the trailer

o Improper loading, overloading and poor weight distribution

He took the time to explain that for the trailer to pull properly, the manufacturer recommends that the weight of the tongue resting on the ball mount be 10-15% of the total weight of the trailer. He said if it’s more than 15% they have what’s called a weight distribution hitch that takes the extra weight off the tongue and distributes it to the tow vehicle axles and trailer where it should be, and if it’s less than 10 %. When you load your load, you distribute it to add some extra weight on the tongue. He looked for the pop-up window he was buying from the brochure and the weight of the tongue was 305 pounds. With the air conditioner installed and your load loaded, it would be in the 10-15% range. He explained that a weight distribution hitch was more commonly used with heavier trailers and in some cases with pop-ups depending on the tow vehicle, but in this case it would not be necessary.

The next thing he asked was if his vehicle had a receiver. You answer, you mean a hitch? He explains that the part that is bolted to the vehicle is called the receiver, and shows him a table that has several different classes of receivers based on how much weight it will tow. The class II receiver was rated for 3,500 lbs. gross trailer weight and 300 lb. maximum tongue weight. For a slight price difference, he recommended a class III receiver rated for 5,000 lbs. gross trailer weight and 500 lb. maximum tongue weight since your trailer tongue weight exceeded 300 pounds.

With that done, he said: let me show you the one component our dealership highly recommends to anyone buying a pop-up. He walked over and took a part of the shelf. This is called friction roll control. We mount one end on the ball mount and the other end on the tongue of the caravan. The amount of friction is adjusted by turning the lever clockwise for more friction and counter-clockwise to reduce friction. He explained that he turns it in 1/8 “increments until it fits where it feels comfortable. This won’t totally eliminate the sway, but once the sway forces are in motion, it will dampen the sway and help you control it when it moves. you are towing your caravan.

Well, he said, that’s it. For less than 10% of the pop-up price, you can do all the hitch work and make sure your family is safe when you go on a trip. At this point, you are convinced that the seller has your best interest in mind and was not just trying to make more money.

You’re ready for the first weekend getaway with your new pop-up window. Complete all of the pre-trip checks the dealer explained to you and you’re good to go. Load the most precious cargo you have, your family, in your vehicle and embark on a new adventure. Take the entrance ramp to the interstate. You are cruising at the speed limit enjoying the music from the radio. Suddenly, out of nowhere, a transfer truck driving twenty miles over the speed limit passes you like you’re sitting still. You feel a slight movement behind you. It was enough to remind you that you are opening the pop-up window. You look at your watch and tell the family that you should be at camp in a couple of hours.

Knowing how to react when a trailer begins to sway can make the difference between your safety and disaster.

Happy Camping,

frames

Copyright 2006 by Mark J. Polk Owner of RV Education 101

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