What Is a Trailer Arm?

Trailer arm is a structure used to couple a tow bar or hitch assembly to the frame of a trailer. It can be a single member or plural component structure, such as first and second spaced apart side frame elements interconnected intermediate to their respective ends by a cross frame member.

1. Weight Distribution

The weight of your trailer, cargo and gear is a major concern when you tow. Regardless of whether your trailer is a small camping trailer or an elaborate, fully-loaded cargo trailer, the weight can cause the rear of your tow vehicle to sag and the front of your tow vehicle to rise, reducing steering control and braking capability.

The best way to prevent this is by ensuring that your trailer has an equal distribution of weight over the axles of your tow vehicle. This can be done by using a weight distribution hitch.

There are several different types of weight distribution hitches on the market, and they all work in a similar manner to help restore balance between your trailer and your tow vehicle. They use spring bars and chains to distribute the tongue weight of your trailer across all axles of your vehicle-trailer combination.

Each system uses a head assembly that attaches to an adjustable shank. The shank can be installed to accommodate most any hitch ball size and can be fitted to whatever coupler you have.

When the head of your weight distribution hitch is attached to your truck, the weight of your trailer pushes down on a set of spring bars that run from your hitch head to a pair of chains that hang down below your trailer. The chains pull the spring bars up to straighten out the trailer.

These bars are connected to the hitch head by L-shaped brackets that bolt into the frame of your trailer. This method of attachment is usually preferred over snap-up brackets because it keeps the bar from moving as you drive.

This method of weight transfer is a common way to reduce trailer sway without the need for sway bars, which can be quite expensive. You can also choose a torsion axle, which uses a steel bar inside the tube to resist wheel movement with torsion forces.

The tongue weight of your trailer should be 10 to 12 percent of the total gross trailer weight to prevent swaying. This is the weight that resides on the Trailer Arm end of your trailer, which is where most of the load is located.

2. Stability

The stability of a trailer is dependent on many factors, including wheelbase length and rear overhang, steering characteristics and the center of gravity. A trailer towed by a truck or van with a long wheelbase and short rear overhang may be less stable than one towed by a short-wheelbase sport utility vehicle, especially while descending a mountain grade at highway speeds.

Another factor that affects stability is the size and weight of the trailer. Larger, heavier trailers often have more weight on the front and rear axles than smaller, lighter ones, resulting in greater sway at high speeds.

Regardless of the type of trailer you tow, it’s important that you don’t exceed the total hitch-to-trailer weight rating. This will help ensure the trailer and your tow vehicle will not cause any instability problems.

A well-balanced trailer will not only have the proper hitch weight, but it will also have the correct amount of tongue load and be equipped with a sway control that is effective in dampening sway under certain conditions. Most manufacturers recommend a hitch-to-trailer weight percentage of at least 12 percent, although higher percentages are available.

Towing equipment that distributes trailer tongue weight evenly to all wheels provides a smoother ride and improved driving comfort. It also contributes to tow vehicle stability by preventing sway that can lead to loss of control.

Most sway controls distribute trailer tongue weight by maintaining upward pressure on spring arms that attach to the trailer hitch ball mount. This pressure is a result of trailer tongue weight and the suspension of your tow vehicle, and works in conjunction with friction sway control to reduce trailer sway.

Sway control brackets are height adjustable to accommodate changes in the trailer’s tongue weight and the suspension of your tow vehicles. These brackets are paired with the sway bars of your weight distribution hitch to form a rigid connection between your trailer and your vehicle, thereby preventing sway under normal conditions.

Sway controls come in two basic designs: the friction-type from Reese and Eaz-Lift and the dual-cam system from Reese, which locks the spring arms into place forming a rigid connection between your trailer and your tow Trailer Arm vehicle. Both are effective in reducing sway, but the Reese dual-cam is recommended for trailers with high hitch weights.

3. Control

The trailer arm is not the only occupant of your vehicle’s cargo compartment. In fact, a few nifty items can be tucked away in the back seat and still come in on the way home. The most important task is making sure your gear is sorted out with the utmost care and attention to detail. The best way to do this is to call your favorite local trailer dealer to ask questions about their latest and greatest offerings in the weight distribution category. You should also be armed with the proper information to discuss with your local mechanic. Most importantly, the right tools and equipment are on hand when you need them most.

4. Safety

When you are towing your trailer, you must be able to safely control it and the vehicle that is towing it. The vehicle needs to be able to accelerate and maneuver quickly; it has to have more room when turning or passing; and it has to have adequate braking capacity.

To ensure safety, you must always follow your trailer’s manufacturer’s instructions when towing. Failure to do so can result in loss of control of the trailer and possibly death or serious injury.

The tongue weight (the amount of load distributed across the front and back of the trailer) must be within a safe range. Typically, the tongue weight should be about 10-15 percent of the gross trailer weight.

If the tongue weight is less than this, it may shift and cause the trailer to become unstable. To prevent this, you must tie down the cargo. Using chains or straps are the best options because they provide greater stability and can be attached to multiple points on the trailer.

Loading your trailer properly is another critical step in preventing trailer sway and instability. Heavy items should be placed low and close to the axle positions as possible to reduce the load on the axle and tire.

You should check your trailer’s load rating to ensure it meets the vehicle’s gross weight limit and that the fifth wheel and king pin are not damaged or worn. If they are, you should have your dealer inspect them and make necessary repairs.

To help you determine the correct weight of your trailer, you should weigh it at a public scale. Ask your dealer about the weighing method and about obtaining certification from the manufacturer that your trailer meets the maximum allowable weight for your vehicle.

When you are towing your trailer, always connect it with safety chains that pass under the trailer tongue and securely attach to the hitch ball. You should also allow enough slack in the chains to take tight-turn situations into account; however, you must be careful not to let them drag on the ground when moving.