What Are Trailer Couplers For:

A trailer coupler is the connection point mounted on the trailer which connects and secures the trailer to the vehicle. There are many variations, but all couplers work by clamping around the hitch ball, there are different ways to attach them, some have a hand wheel to tighten the clamp to the ball, others use a lever or a toggle to lock the coupler.

When the lever is flipped to the locked position, the clamp is pulled up against the underside of the hitch ball. The fit should be snug but not too tight (binding) and if left too loose there is a danger of the coupler detaching from the hitch ball.

Selecting A Coupler:

Trailer hitch couplers are rated by weight class, there are 5 classes, see chart below. It is important to match the trailer coupler and hitch ball to the proper loaded weight of the trailer. Once you have determined the tongue weight and gross trailer weight and have found out the towing capacity of your vehicle, then it is time to choose a hitch coupler, there are many different types:

Hitch Class Max TW (WC) Max GTW (WC) Max TW (WD) Max GTW (WD)
I up to 200 lbs. up to 2,000 lbs. N/A N/A
II up to 300 lbs. up to 3,500 lbs. N/A N/A
III up to 600 lbs. up to 6,000 lbs. up to 1,000 lbs. up to 10,000 lbs.
IV up to 1,000 lbs. up to 10,000 lbs. up to 1,400 lbs. up to 14,000 lbs.
V up to 1,200 lbs. up to 12,000 lbs. up to 1,700 lbs. up to 17,000 lbs.


Straight Tongue/Channel Style – coupler has a square tubular mounting sleeve or tongue that can be bolted or mounted to a trailer. Designed for trailers with a straight channel tongue or bar.

straight tongue trailer coupler

Round Tongue – the coupler slides into round shank tongues and welds on, they have a spring-loaded collar that ensures a snug fit.

round tongue trailer coupler

A-frame – attaches to A-shaped trailer tongues, they are solid stamped steel couplers that are used for heavier loads.

a-frame trailer coupler

Flat Mount Couplers – instead of a channel the mounting face is flat and can be bolted or welded. These are used as an alternative to tow rings or pintle hooks, it mounts on the end of the trailer tongue and is used for heavy trailers.

flat mount trailer coupler

Gooseneck – long tubular shaft coupler that is used with a gooseneck hitch, which is commonly used on heavy trailers such as a horse trailer.

gooseneck trailer coupler

Adjustable Couplers – Adjustable trailer couplers offer the user the flexibility of using different sizes or classes of couplers; the ability to adjust them up or down to match tow vehicle height; or swap them out with other options like a clevis or a pintle ring.  The channel (4-hole, 6-hole, 8 holes etc.) welds directly to the frame, and your choice of coupler bolts into the channel.

trailer coupler

Channel or A-frame couplers are most common with class I, II, and III trailers, channel couplers slip over a square steel tube or tongue while A-frames mount on an angled A-frame tongue. An A-frame coupler have a wider base, so they can bear more weight.

a-frame trailer coupler

After you have chosen the correct coupler you require, then comes installation. You could do it yourself if you have a firm grasp on how to install it, but in some cases where welding is necessary, you may have no other choice than to have it installed professionally. If you purchase a Channel or and A-frame coupler, you may be able to install it with hand tools.

trailer coupler pic

Whatever you choose, the trailer coupler must match the tongue on your trailer. Most of the time the coupler has pre-drilled holes for inserting mounting bolts, before bolting the coupler to the tongue, ensure that everything fits properly. A properly fitting coupler will butt up against the tongue and allow for maximum overlap, essentially your installed coupler will become an extension of the tongue, for this reason you may choose to weld the two components together, however, bolting the two should provide enough strength.

Be safe and always ensure that your equipment is the correct size and installed correctly!

proper fitting trailer coupler
Published On: February 25th, 2020 / Categories: Tips /
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