A coupler is the metal piece that physically connects your trailer to the tow vehicle. Once the coupler is permanently bolted or welded to your trailer's frame rail(s) at the front (this is the "tongue" area), it then fits over the round ball on the trailer hitch attached to your vehicle. Levers of various designs on the coupler clamp around the round ball tightly enough to prevent it from disconnecting, but they also allow just the right amount of play for proper pivoting around turns and over road undulations.
Couplers are subject to a large amount of wear-and-tear. They are called into action every single time you connect and disconnect your trailer from the tow vehicle. They move and bounce around on top of the trailer ball as you're driving. If you leave your trailer outside, they are exposed to the elements. Eventually, the release mechanism becomes sticky, or the fit on the trailer ball becomes loose, or corrosion begins to take hold. Instead of replacing your entire trailer, which is expensive, the coupler is replaceable separately. It's a cost-effective and convenient way to ensure that your trailer-to-hitch connection remains as secure as possible.
Trailer tongue shape determines the type of coupler you'll need. Specifically, trailer tongues are known as "A-frame" when two frame rails join together at a 50 degree angle at the front (industry standard), "straight" when one single frame rail serves as an attachment point, or "gooseneck" when a trailer uses a round vertical post bolted underneath the front of the trailer. The coupler must also match the size trailer ball you're using. If they don't match, you might be better off replacing the coupler if it's old.
In the scope of this article, we'll concentrate on these main types of couplers and related parts - guiding you through the products we offer on the Trailer Couplers section of our website.
Adjustable Couplers:
Unlike most couplers which are designed to bolt or weld directly onto your trailer, adjustable couplers are designed to bolt to a separate vertical metal bracket. On this bracket piece, a series of holes positioned at different heights provides the "adjustment" needed because the coupler can be attached high or low as needs dictate. This allows a huge amount of flexibility when you've got more than one trailer, or when load weight changes a trailer's ride height.
The Curt Adjustable Coupler (with Collar Style Lock) offers a hinged jaw opening design that can handle 7,000 lb. to 15,000 lb. For towing heavier loads, a heavy-duty version in Product Options can handle 15,000 lb. These coupler plates come with two bolts that allow them to be mounted at a number of height positions. With any of them, you'll need either a Curt 3-position or 5-position eye channel bracket which are sold separately.
Pro Series offers their Adjustable Coupler in 8,000 and 14,000 lb. versions (see choices within the Product Options drop-down). Additionally, Bulldog offers an Adjustable Coupler with collar sleeve in multiple weight ratings up to 15,000 lb. Since Pro Series and Bulldog are Cequent brands, both of these adjustable couplers are designed to fit the Bulldog Trailer Coupler Adjustable Accessory mounting bracket which is sold separately in 4- or 5-position sizes.
Couplers For A-Frame Trailers
A-frame couplers are designed to fit over the very front end of the trailer where frame rails join together. Since industry standards specify a 50 degree angle, there's no special consideration needed when purchasing any A-frame coupler - except for personal preference when it comes to choosing a trigger latch or sliding collar release mechanisms. Popular uses for A-frame design tongues are landscape trailers, utility trailers, and car haulers from 5,000 to 15,000 lb. A-frame couplers are usually intended to be welded onto the trailer frame rather than bolted in place.
Space between the frame rails at the front of an A-frame trailer allows fitment of specially-designed jacks to raise and lower trailer height via a crank handle. All of the A-frame couplers we offer are built with a round hole for the jack post with three bolt holes surrounding it. Hole positions conform to universal industry standards, so they'll fit any jack you already own as well as trailer jacks we sell.
If you prefer A-frame couplers with sliding collars and hinged jaws for releasing and locking, we've got the Curt Collar Style Sleeve-Lock A-Frame Coupler (2&5/16th inch trailer balls) rated for 12,500 lb. trailers, and we offer the Bulldog A-Frame Coupler with versions that can tow up to 15,000 lb. On this style of coupler, the collar piece slides back, then the hinged jaw over the front of the ball opens wide like an alligator's mouth. After it's placed over the tow hitch ball, the jaw can be shut with hand pressure or by sliding the collar forward into its locked position.
We have the Pro Series A-Frame Coupler for 2" Hitch Balls rated for either 5,000 lb. or 8,000 lb. trailers. If you need more capacity, consider the Fulton A-Frame Coupler: the 2" hitch ball model is rated for 5,000 lb., available in black primer or zinc; the 2 5/16" ball model is available in capacities from 10,000 lb. to 14,000 lb., and in a variety of finishes. Both of these are equipped with trigger handles for attachment and release, and they feature traditional round holes for trailer jacks. Should you have a trailer jack that requires a mounting hole that's open on one side, take a look at the Fulton F2 A-Frame Coupler rated for 10,000 lb.
Couplers For Straight Tongue Trailers
Trailers with a single frame rail in the front are known as "straight tongue" trailers, and they are typically found on smaller, light-duty applications up to 6,000 lb. or so. We’ve got a number of straight tongue couplers. For starters, the Fulton Straight Tongue Coupler has a trigger style latch and is available in primed or zinc finish. In the Product Options field, select hitch ball size, either 1 7/8" or 2", then choose the size you need for the tongue mount. The coupler for the 1 7/8" ball is rated at a 2,000 lb. GTW (gross trailer weight). The 2" ball coupler gives you a choice among 3,500, 5,000, or 6,000 lb. TW (tongue weight).
If you prefer a straight tongue coupler with sliding collar release, the Bulldog Straight Coupler has both a sliding lock collar and a trigger style pull handle. Ball sizes are either 2" or 2 5/16", with coupler capacity up to 12,500 lb. In the Product Options field, Bulldog offers you a choice of sleeve lock, collar lock, safety pin, and trigger handles.
Couplers And Parts For Gooseneck Style Trailers
"Gooseneck" trailer couplers are designed to be used in the bed of pickup trucks. These couplers bolt onto the vertical post attached underneath the front of a trailer, then they secure to a flat, horizontal plate and trailer ball mounted in the pickup bed. Gooseneck coupler posts (or "tubes") can be round or square in shape, and we offer both styles.
If you're looking for a square gooseneck coupler, take a look at the Bulldog Square Gooseneck Coupler for 3" Ball. You'll also find individual coupler accessories in this same style such as adjustable height welded tubes, square outer tubes, and miscellaneous hardware that includes pinch bolts, set bolts, and locking pins. For round coupler tubes, Pro Series offers the Round Gooseneck Coupler with either dual set bolts, or single set bolts with 4 holes for height adjustment.
And if you're looking for a replacement gooseneck adapter box for a Lippert Component trailer frame system, we've even got the Reese 2 5/16" Gooseneck RV Coupler Goose Box. The "goose box" mounts to the trailer and serves as a structural reinforcement and a connection for the gooseneck coupler pole. Reese has built it to meet or exceed OE specifications when it comes to strength and longevity, and it's been shown to enhance ride comfort with dual shock absorbers, rubber bumpers, and built-in air bladders.
Coupler Handles
If your coupler has pre-existing holes on the side (Fulton and Bully single tongue trailer couplers are two examples), we offer grab handles designed to bolt on to the side of the couplers. Once attached, the handle makes it easy to lift and turn a smaller, lightweight trailer which is stationary. Choose the C.E. Smith Trailer Coupler Lift Handle, or the Fulton Coupler Handle.
Coupler Locks
For security, we’ve got a wide variety of coupler locks that are shaped and sized to keep any style of coupler secured in place. Curt makes several different styles of coupler locks, including an adjustable stainless steel model, an aluminum lip coupler lock, and a solid brass pin lock. The Tow Ready Coupler Lock is a unique design, with the lock consisting of a "ball" which is locked into place in the coupler itself.
Other Accessories And Repair Parts
We’ve got a number of repair kits that allow easy replacement of moving parts that can wear out (see choices within the Product Options menu). For example, the Bulldog BX1 Repair Kit comes with a handle, locking cam, grooved pin, and related hardware for gooseneck couplers.
If you've got a longer trailer but limited space to keep it, the Fulton Trailer Beam Fold-Away Weld-On Hinge Kit lets you cut part of your straight trailer tongue off. Once it's cut off, the hinge kit attaches between the severed piece and the trailer frame. The hinge allows the severed tongue piece to be folded out of the way when the trailer isn't being used. When it's time to tow, that section is folded back and locked in place straight ahead.
Play it safe! Inspect your trailer coupler on a regular basis. Review the replacement choices in our Trailer Couplers section which will show you what is available for sizes, weight ratings, finishes, and other variables. Be sure to also look in the Product Options drop-down menus. A new, affordable trailer coupler will give you the security and peace of mind you want when you're trailering.