Larry_Loo

  Having read the posts about Hank2's accident on RVnet and those about the accident on this forum, it seems to me that many RVers feel that a mismatch between a heavy trailer being towed by a light vehicle might induce swaying. If this has become a commonly held conclusion, then it is incorrect. The size and weight of the towing vehicle has little to do with inducing swaying of a trailer. Swaying of a trailer results from its lateral instability on the road surface over which it is being towed. A well-designed and maintained large trailer that is properly loaded will not be susceptible to swaying when road conditions are good. On the other hand, a poorly designed or poorly loaded small trailer may be capable of severe swaying even under the best driving conditions.
  I can tell you from experience that this is true. Over 30 years ago the first trailer I ever towed was an 6' long box trailer that my wife and I rented to haul some of our belongings from California to Texas. Out in the countryside just a few miles down the road I felt the trailer wagging from side-to-side. This wagging worsened and I felt the rear wheels of our Buick station wagon moving side-to-side in rhythm with the trailer. I quickly learned that braking made it worse; fortunately I quickly discovered that taking my foot off the accelerator, downshifting into a lower gear and then accelerating stopped the swaying. We continued this way for hundreds of miles - until, somewhere in New Mexico the right wheel of the trailer came off. This occurred, fortunately, while we were driving slowly through a road construction detour. The mechanic dispatched by the national rental agency found all of the wheel's lugs sheared off! I suspected that the frequent bouts of swaying had put severe stresses on the lugs. On another occasion while towing a load of lumber in my own 6' box trailer, I experienced severe swaying that blew out one of its tires. After changing the tire, I drove home at a snail's pace to keep the swaying under control.
  I am not stating that the weight and power of the towing vehicle is not important. It is, but only in determining the extent of damages that can result from a trailer's swaying. That is, the heavier the vehicle the less likely it is that it will be pulled out of control and overturned by a swaying trailer. This is where the match between trailer and towing vehicle makes a difference where swaying is concerned.

There are many factors that can lead to a trailer's swaying: lack of auxiliary brakes on a trailer, improperly adjusted brakes, slippery road surfaces, poor tires, high winds, etc. In a well-maintained trailer the one other factor under the driver's control is the location of the trailer's center of gravity. When loading a trailer drivers should keep in mind that most of the load (and therefore its center of gravity) should be located forward of the trailer's axle. Exactly where this should be will differ from trailer to trailer. Suffice it to say, TrailManor recommends that the (trailer be loaded so that the) weight on the tongue should be approximately 10% of the trailer's gross weight. A TM trailer loaded like this will be laterally stable. As the center of gravity is moved farther back, less stability can result. Finally, if enough load is placed in the rear, the center of gravity can be moved rearward of the axles. This results in an extremely unstable towing condition, with swaying imminent the moment any lateral forces (wind gusts, going around a curve, etc) are exerted on the trailer. The reasons for the instability have to do with lengthening the moment-arm of the center of gravity as it moves to the rear. The greater the moment-arm of the center of gravity, the more its tires have to fight to maintain forward motion and minimize swaying.
  You can demonstrate this to yourself by taking a broomstick and tying a 1 pound weight on its far end. Your hand holding the near end of the stick simulates the hitch; your other hand farther up the stick simulates the trailer's wheels. As you swing the 1 pound weight slightly from side-to-side, judge how much force both hands must exert to resist the inertia of the weight. This is similar to an unstable, rearward center of gravity. Then untie the weight and retie it about 18 inches from the near end. Now straddle the weight with your hands and repeat the swinging of the weight from side-to-side. It should now be evident to you that your hands can much more easily control the side-to-side inertia of the weight. This is just like towing a stable trailer with a properly located center of gravity.
  If you tend to load up your TM with lots of heavy items, you might consider weighing your goods and purchasing a tongue scale. That way, you can at least assure yourself that as you maintain the proper proportion of weight on your hitch, you'll be keeping the trailer's center of gravity about where it should be. ;D