null

ProPride Hitch: Trailer Sway Facts

Posted by ProPride Hitch on 6th Jan 2022

ProPride Hitch: Trailer Sway Facts

When it comes to towing, it’s critical to know all the facts and approach everything as safely as possible. Matter of fact, here’s the first one: Safety is always the top priority.

At ProPride Hitch, we want to make sure that your experience on the road is enjoyable and trouble-free, from start to finish.

The following are useful facts/definitions that will help you get the most out of your towing experience. We want you to be familiar with terminology and learn how to assess and correct potential issues.

Following the definitions/facts segment, we’ll get into the causes of trailer sway.

FACTS/DEFINITIONS

The 3P Hitch will be the last hitch you buy

We might be biased, but the reviews don’t lie! The 3P Hitch is the industry standard and dramatically increases safety upon installation. Eliminating sway, the need for corrective driving and providing a smoother ride – the 3P has no equal, and we stand by that. The 3P is the last hitch you’ll ever need.

Friction is your enemy

In the towing world, friction can cause major problems. The 3P Hitch helps eliminate friction by stiffening the connection between TV and TT. This causes the combined mass and rotational inertia of the TV and TT to resist forces which are attempting to make the TT “sway.”

It’s important to understand these acronyms

  • GCRW: Maximum total load of a towed combination
  • GTWR: Maximum allowable load of a trailer that is loaded. It includes the weight of the trailer itself, plus the fluids and cargo. Note: this is sometimes designated as the GVWR of the trailer.
  • GVWR: Maximum allowable total weight of a vehicle or trailer that is loaded. It includes the weight of the vehicle or trailer itself, plus the passengers, fuel and cargo.

Oscillating/Oscillation

A movement back-and-forth between two limits over time. Amplitude is the displacement of the oscillation wave.

Translation: When two things are moving side-to-side/back-and-forth, problems become more than “potential” – they become inevitable.

Overhang

Overhang is the horizontal distance from the center of the rear axle, to the rear end of the tow vehicle.

Pivot Point

The point at which the towed trailer pivots to create a tow angle – self-explanatory, right?

Pivot Point Projection ™

Well, we’re experts in this area… The 3P controls the trailer’s effective pivot point. Learn more about it by visiting the 3P Hitch page.

Tongue Weight

The static downward force exerted on the hitch ball by the trailer coupler. Basically, it’s how much weight/pressure pressing down on your hitch ball.

Tow Angle

The angle created between the tow vehicle and trailer when the trailer moves away from the centerline of the tow combination. A trailer in-line with a tow vehicle has zero degrees of tow angle. A tow angle of zero, to a maximum of 90 degrees, allows the trailer to be towed around a corner.

Tow Rating

The allowable weight limit for a tow vehicle. GCWR minus GVWR of the two vehicle.

Trailer Sway

It comes down to oscillating tow angles. This last definition is important in our discussion. A tow angle created by turning a corner is NOT trailer sway. Trailer sway is defined as “oscillating tow angles” – that is multiple tow angles over a period of time. The trailer continues to oscillate away from the centerline of the tow combination at various amplitudes. Clear? We hope so, because this is where most discussions we’ve witnessed start to break down…

Weight Distribution

The act of distributing the load exerted on the hitch ball, the tongue weight, onto the tow vehicle and trailer axles.

Wheelbase

The horizontal distance between the center of the front axle and the center of the rear axle on the tow vehicle.

Yaw

The side-to-side movement of the trailer on the hitch ball.

Causes of Trailer Sway

Towing Speed

Typical highway speeds have become much greater during the past 50 years. The speed at which you decided to tow your trailer may be the single-greatest factor in controlling trailer sway. Unfortunately, tests show that any speeds greater than 45 mph tend to cause almost any trailer to sway. With traffic traveling at much greater speeds, it isn’t practical – and most of the time, illegal – to travel at a speed that will control trailer sway.

High Winds

Winds blowing perpendicular against the side of a towed trailer push the trailer, pivoting on the hitch ball and creating a tow angle. The greater surface area of the side of the trailer, the greater the force will be at any given wind velocity. Towing in high winds is never a good idea and should be done cautiously – and only if necessary.

Gusting Winds

Winds can gust and increase in velocity due to weather. Winds can also be described as gusting when a high wind is blocked by a tree line or a bridge overpass, and you clear this blockage while towing. Your trailer goes from a relatively low side force, to a much higher side force that pivots the trailer on the hitch ball, creating a tow angle.

Bow Waves

A bow wave is a wind produced by a large semi-truck, box truck or van pushing its way through the air on the highway. This wind travels around the truck and down the sides, creating a wind disturbance in the adjacent lanes. This win disturbance creates a sudden high-to-low pressure in the air traveling down the side of your trailer. The bow wave, as with the other wind disturbances, creates a tow angle by pushing the trailer and pivoting it on the hitch ball. The bow wave produces a “sucking” feeling in some combinations - and that feels like the entire tow combination is being pulled into the other lane.

Bad Roads

This one is self-explanatory, right?

With any type of travel across this great country, you’ll realize that there are quite a few roads that need work – especially in Michigan. These uneven, poor roads can make a trailer become unbalanced, causing it to pivot on the hitch ball and creating a tow angle.

Downhill Towing

Towing downhill can allow your trailer to roll faster than the tow vehicle. The tow vehicle is geared to slow down when you let your foot off the accelerator. However, trailers are not equipped with this feature. When the trailer is traveling at a higher rate of speed than the tow vehicle, it can begin to yaw (move side-to-side).

Poor Trailer Design

The fact is that some trailers are designed better for towing than others. Trailer design includes a lot of different variables that need to be addressed to properly balance the trailer for towing. Even with a good trailer design, the designer can have a hard time determining the optimal layout of the trailer, because of the added dimension of the trailer being used by so many different customers.

Improper Loading

Trailers are very sensitive to where you can place your load/cargo. Your black and gray water tanks, your supplies, your clothing and anything else you carry with you, will change the weight of the trailer and how the weight is distributed throughout your towed combination.

Poor Weight Distribution Hitch Adjustment

When a weight distribution hitch is not properly adjusted, it can cause your trailer to have either too much tongue weight or not enough tongue weight, to avoid inducing sway.

ProPride Hitch hopes that this article provides valuable information, helping you to understand terminology and recognizing how to eliminate sway.