Trailer Hitches

Trailer hitches join a towing vehicle with a trailer to ensure a safe connection between the two for transport.  Trailer hitches come in all sizes and shapes for a variety of applications. Trailer hitches are classified as either weight-carrying or weight-distributing.

Weight-carrying hitches (such as a bumper pull) are recommended for use when the trailer weight (including cargo) is 5000 lbs. or less. Make sure the tow vehicle is rated by the manufacturer to accommodate that load. The tongue weight is carried directly on the rear of the tow vehicle and on the hitch. You can find your vehicle's tow rating online at www.campinglife.com or download a listing of tow ratings at www.trailerlife.com .

Use weight-distributing hitches for heavier loads. These hitches redistribute the tongue weight  throughout the frame of the tow vehicle. The result is that the trailer's weight is distributed among the trailer axles and the front and rear axles on the tow vehicle. Ask  about weight distribution hitches if you intend to tow using a "bumper" type hitch or hitch receiver.

Fifth wheels and goosenecks are two weight-distributing hitches used most often with pickup trucks. The weight of the trailer is carried directly over the rear axle with the hitch mounted in the truck's bed.

A fifth wheel hitch is used for larger trailers and is a small version of the type of hitch used on semi trucks. A gooseneck coupler attaches to a tow ball that usually is mounted in the bed of a pickup truck. Underneath the bed are support rails that are bolted or welded into place.

A frame-mounted hitch is one where the hitch is attached to the frame of the tow vehicle. This gives more stability to a bumper pull type of hitch.

Before every trip, check the tow ball and coupler to ensure they are the same size and that all bolts are securely tightened. Also, make sure the latching mechanism is locked in place.

For conventional smaller trailers known as bumper pull, there are two different kinds of frame mounted or bumper mounted trailer hitches to choose from: weight-distributing and weight-carrying. Fifth-wheel trailers can use two completely different kinds of trailer hitches, but they are beyond the scope of this article.

A weight-distributing trailer hitch is made of spring bars that connect to the ball mount and the trailer frame. This is done so that the trailer hitch and trailer axle’s weights are distributed properly amongst themselves and with each other. When correctly used, a weight-distributing trailer hitch keeps the towing vehicle and the pulled trailer level once the full weight of the trailer has been placed on the ball mount. Because a weight-distributing trailer hitch can be somewhat unstable (especially when turning corners), sway control devices are often used.

Alternatively, a weight-carrying trailer hitch bears all of its weight on the ball mount (or the ball itself if a ball mount is not used). If the weight of the trailer hitch is sizeable, the rear of the tow vehicle will initially face downward, but as the towing vehicle is weighted down, the front of the towing vehicle will rise. Because this may result in diminished front-brake efficiency and generally poor towing vehicle handling, weight-carrying trailer hitches are rated for lightweight towing only. Like weight-distributing trailer hitches, sway-control devices can be used with weight-carrying trailer hitches, depending upon what exactly is being towed.

Trailer hitch Classifications

Conventional trailer hitches are manufacturer-rated according to the highest weight they are able to pull. The highest weight calculation includes having the trailer’s freshwater tank full, the propane tank and/or cylinders full, and all necessary items loaded. The trailer hitch ratings are as follows:

·        Class I Trailer hitches: up to two thousand pounds.

·        Class II Trailer hitches: up to three thousand, five hundred pounds.

·        Class III Trailer hitches: can be either weight-carrying or weight-distributing and are rated for up to five thousand pounds.

·        Class IV Trailer hitches: includes both weight-distributing and fifth-wheel trailer hitches and are rated for trailers between five thousand and ten thousand pounds.

·        Beyond Class IV Trailer hitches: greater than ten thousand pounds.

Conventional Trailer hitch Hardware

A conventional trailer hitch platform is attached under the bottom of the towing vehicle. The very back of the platform is where the receiver is housed. The receiver is where a section of reinforced square tubing is placed into the shank of the ball mount.

1.    Ball Mounts

Lightweight trailer hitch loads use ball mount shanks made of square steel tubing, whereas heavy trailer hitch loads require a solid shank. In both cases, the shank has a hole punched through it that lines up with holes on opposite sides of the receiver. When the hole in the shank is lined up with the holes in the receiver, a hitch pin is inserted and held in place by a clip or lock. The  ball mount attaches to the end of the shank. Some ball mounts adjust to accommodate different coupler heights and permit fine tuning of the trailer hitch, which in turn improves towing performance. Once the ball mount has been adjusted and set up, it should never require changing or retuning unless it is used with a different towing trailer or towing vehicle.

2.    The Ball

Balls are installed on the ball mount. Balls are available in sizes ranging from 1 7/8 inches to 2 5/16 inches, and have a variety of risers that raise the ball above the ball mount for proper positioning. Balls are rated for loads ranging from two thousand to ten thousand pounds. Make sure that the ball used is rated equal to or greater than the gross vehicle weight rating (GVWR) of the trailer.

3.    Spring Bars

Spring bars are used with weight-distributing trailer hitches to spread the trailer hitch weight among the trailer and tow vehicle axles. Spring bars are rated in various weight capacities because the proper ones must be used to allow the load-distributing system to work. Generally speaking, use a spring bar that is rated up to two hundred and fifty pounds more than the actual trailer’s trailer hitch weight to be safe.

4.    Safety Chains

Safety chains and hooks (or other attaching devices) are only used safely with trailer hitches when they are rated higher than the GVWR of the trailer. The chains are installed properly if they run from the A-frame to a series of loops fastened securely to the trailer hitch receiver, are loose enough to allow sharp cornering but tight enough to prevent dragging.

When attached correctly, trailer hitch safety chains cross under the coupler so that if the trailer were disengage, the A-frame would still be propped up above the round in the framework of the crossed chains.