A-Z Towing Terms: A Guide for the Savvy Camper
by Sean Woodruff, on Jun 21, 2019, 8:45:00 AM
Maybe you've just gotten your first trailer or RV and can't wait to hit the road. Or maybe you're a veteran camper but you've just had your first frightening experience with trailer sway. Either way, you've realized you need a better understanding of how your towed trailer or RV will actually behave on the road.
Towing a trailer or RV safely requires more than just knowing how to hook it up. You need to understand how towing truly works, how wind and other forces act on your trailer, and what you can do to guard against and react to trailer sway while towing. You also need to understand what your specific trailer hitch mechanism is doing to reduce sway and balance weight.
One way to become more familiar with towing is to learn the basic vocabulary. Not only will this help you really "get" the core concepts of towing safety, but you'll also be better equipped to talk to other drivers, mechanics, and sales staff about your trailer or RV.
At ProPride, we want you to know as much as possible about towing, so we've created this helpful guide to some fundamental towing terms.
Amplitude - As it relates to trailer oscillation, amplitude is the degree to which an object moves back and forth between two limits.
Friction Control - Creating friction between two surfaces to inhibit trailer sway. Many towing hitches incorporate friction to help manage trailer sway.
"This method [friction sway control devices] works well in smoothing out the smaller sways and preventing some from increasing for a more comfortable trailering experience. There are limitations on the amount of sway that these hitches can control and as trailer sway intensity increases; the sway control effectiveness is diminished."
-Alan J. Hoogenakker, Consulting Engineer, Trailer Product Development
Gross Combined Weight Rating (GCWR) - The maximum possible combined load of a vehicle and trailer. Having your towing setup weighed at a weigh station gives a truly accurate combined weight, compared to estimating your load.
Gross Trailer Weight Rating (GTWR) - The maximum possible load of a trailer, including contents and the trailer structure itself.
Gross Vehicle Weight Rating (GVWR) - The maximum possible load of a vehicle, including passengers, contents, and the vehicle itself.
"Always keep in mind every tow vehicle has a maximum tow capacity and you must compute total RV weights including, passengers, cargo, and fluids and fuel. Also keep in mind that any weight added to the tow vehicle takes the same amount of weight from the towing capacity."
-Mark Polk, RV 101
Oscillation - A movement back and forth between two limits (from a baseline).
Overhang - On a tow vehicle, the distance between the center of the rear axle to the rear end. Essentially, how much of the vehicle "hangs over" beyond the rear axle.
Pivot Point - The point at which a towed trailer pivots in relation to the towing vehicle. Understanding where a trailer's pivot point lies is critical to understanding trailer sway and can also be a huge help when trying to back up with a trailer.
Pivot Point Projection™ - A hitch design that virtually moves the trailer's pivot point to reduce sway. The trailer still pivots at the ball when making normal turns, but the pivot point is projected when the trailer begins to move side to side.
Tongue Weight (TW) - The force exerted down onto the hitch ball by the trailer coupler when connected. It's important to mitigate tongue weight with the right hitch setup.
Tow Angle - The angle between a towed trailer and the towing vehicle, measured from the center line. A trailer perfect in line has a tow angle of 0 degrees, while higher angles (up to 90 degrees) are created when turning.
Tow Rating - The allowable weight a vehicle can tow (excluding the weight of the vehicle itself)
"The weight issue is probably the most critical and least understood issue you will confront when purchasing a towable RV. It is critical because a mismatched tow vehicle and trailer can put you and your loved ones safety in jeopardy. It can also result in expensive repair bills for damage and premature wear to major components on your tow vehicle. It is the least understood issue because the buyer is not educated on weight concerns until it is too late."
-Mark Polk, RV University
Trailer Sway - We really want drivers to understand that "trailer sway" doesn't just mean any trailer movement - it refers to oscillating tow angles. Unlike the normal tow angles created when turning with a towed trailer, sway refers to back-and-forth movement away from the center line.
Weight Distribution - Shifting the weight away from the trailer coupler and hitch ball and into the trailer and tow vehicle axles. Towing without good weight distribution creates unnecessary strain on the hitch. Evenly distributing items in your trailer helps with weight distribution, as does placing heavier items over the axles, but a weight distribution hitch is key for heavier trailers and RVs.
"Rather than the rear axle of the tow vehicle taking on all of the weight of the trailer, a weight distribution hitch transfers the weight evenly across the frame of the trailer and the frame of the tow vehicle."
-Steve Fennell, RV Life
Wheelbase - The distance between axles on the tow vehicle.
Yaw - The side-to-side movement of the trailer on the hitch ball.
Learn More About Towing Terms
If you want to dive deeper into the foundations of safe trailer towing, a quick course can help. You can find local courses through RV Basic Training and RV School, or take advantage of online resources like RV 101 With Mark Polk. Of course, the team at ProPride is happy to help you with any questions you have about towing.
Once you have these terms in your vocabulary, you can use them to better understand how your trailer behaves and make better predictions to prevent trailer sway. At ProPride, we're committed to help drivers avoid trailer sway and improve their towing safety. Contact us today to learn more about our solutions and talk to our helpful team of towing experts.