How Drop Hitch Receivers Work

Close-up photo of trailer hitch.
A trailer hitch receiver like this one helps people ferry trailers and other large items, but you need a drop hitch receiver to make sure your vehicle stays upright.
Dan Driedger/

Sure, cars, trucks and SUVs work great for ferrying you and yours from Points A to B. But in a society that's grown fond of acquiring and using lots of stuff -- and schlepping it around with us -- our vehicles alone aren't always fully up to the task.

Thank goodness we have trailers to help haul some of the bigger stuff. They come in handy, for instance, when you and a chum want to take a couple of dirt bikes to test your mettle on a hidden trail. A trailer is an absolute necessity when you want to get a boat from your driveway to the launch down by the local fishing hole. For all their functionality, though, trailers come with a host of logistical questions: What's the best way to hook them up? Can my car, truck, or van handle this towing job? Do I have all the hitch accessories I need? As a responsible driver and trailer owner, you must resolve these questions before you can safely and legally hit the open road with your toys and other stuff in tow.


Fortunately, learning how to properly select and use towing equipment isn't rocket science. This article deals with what to do when the receiver hitch of your vehicle comes up short (or tall) compared to the tow apparatus of the trailer you're using. And yes, we'll define and explain all of the common names for the towing set-up parts that you'll need. The hitch accessory you'll be most concerned with to get your vehicle's towing gear matched in height to the trailer, is the drop hitch receiver.

­Drop hitch receivers have one purpose -- to alter the height of the trailer hitch receiver. If you have one, it would be the square, steel tube that's bolted to the rear underside of your vehicle. A drop hitch receiver allows you to connect a trailer without fear of it unbalancing the vehicle and possibly causing you to lose control.

You may have seen vehicles laden with a trailer and the vehicle's rear sagging like an overloaded mule with the weight. This is a potentially hazardous situation, since that "sag" shifts weight away from the front wheels and weakens your steering efforts. Having the right hitch accessories can reduce or eliminate this problem by leveling the trailer and evenly distributing its weight.

Drop hitch receivers fit into a standard receiver hitch opening and can add 2 inches to more than 10 inches of vertical space with which to evenly connect a trailer. If your vehicle has four wheels, chances are that some manufacturer has made towing equipment that fits it. In the next section, we'll examine how to choose a drop hitch receiver.



Choosing Drop Hitch Receivers

drop hitch receiver

Your first consideration when considering any towing equipment is, "What will it do to my vehicle?" Always check your vehicle's owner manual for towing limitations and tips. Towing more weight than your vehicle was designed to handle can overwork your engine and brakes, and substantially increase the odds of an accident. When it comes to towing, always play it safe!

Makers of new cars and trucks often offer a "towing package" that features beefier brakes and a larger-capacity cooling system for the engine, as well as the necessary towing hardware itself.


In the United States, tow hitch receivers come in categories ranked by the weight of their towing capacity:

  • Class 1 - 1,000 to 2,500 pounds gross trailer weight (combined weight of trailer and contents)
  • Class 2 - 3,500 GTW
  • Class 2.5 - 4,000 GTW
  • Class 3 - 6,000 GTW
  • Class 4 - 8,000 GTW Class 5 - 10,000 GTW

Assuming you've already had the appropriate class of trailer hitch installed on your vehicle, you'll want to figure out how much height separates it from the connecting part of the trailer.

The entire trailer hitch assembly consists of a few simple components. The trailer hitch receiver forms the base: It's a tubular steel frame welded in a configuration that snugly bolts to the underside of the vehicle. It has a square opening (between 1 ¼" to 2 1/2" across, depending on class) to accommodate the drop hitch. The drop hitch consists of additional pieces of rectangular welded steel and it extends the "reach" of the ordinary trailer hitch. It fits into the original trailer hitch on the vehicle and secures with a locking pin. The ball mount mates a short length of square steel tubing to a steel flange. This thick flange provides a platform with a hole drilled through it. The hitch ball fits through that hole. The entire ball mount connects with the trailer hitch receiver quite simply, with a locking pin. The hitch ball then secures to the ball mount by means of a threaded shaft and a nut that locks it into place. Make sure that the size of your ball hitch (ball diameter) matches that of the trailer's coupler. If you have trouble determining the proper specifications for your hitch accessories, you can always bring your vehicle to a reputable dealer or tow kit customizing shop.

Sophisticated electronics have taken over several crucial systems on cars, trucks and SUVs. But towing accessories remain an area where the driveway mechanic can still tinker without being a computer whiz. To learn how to install a drop hitch receiver, go to the next page.


Installing Drop Hitch Receivers

Photo of trailer with hitch exposed.
Believe it or not, attaching a trailer to a vehicle using a drop hitch receiver is quite easy.
Brad Wieland/

Many manufacturers of drop hitch receivers and other towing equipment try to make their products as "bolt-on" as possible. In other words, the products are designed to attach to your vehicle with simple tools, no complicated wiring, and little to no modification to the component itself or your vehicle. If welding is required, it definitely is not a bolt-on mechanism.

­Experienced wrench-turners, however, know that "bolt-on" often means there may be some light to moderate filing, sawing, jimmying and crow barring in order to make a part fit perfectly and flush. Installing drop hitch receivers and other towing equipment can directly affect the safety and performance of your vehicle. It's imperative that you follow the torque specifications for fasteners and use locking washers as directed. You should call in a professional if you're an inexperienced installer or feel uncomfortable performing such work.


That said, the procedure for installing a drop hitch receiver is pretty straightforward. In fact, a drop hitch is even easier to install than a "bolt-on": It merely requires inserting into the car or truck's normal receiver hitch and securing with a locking pin. [Source: Blue Ox]

That said, you can purchase an assortment of hitch accessories that enhance safety and control of a load, including weight distribution hitches, sway control devices and stabilizers. While these may be a bit more complicated to install, they can further ease some of your worries while towing a trailer: Wind gusts, passing trucks and inconsiderate drivers make towing much more demanding than normal driving. Slowing, stopping and turning require greater care and advanced planning when you're towing a trailer. The additional hitch accessories mentioned are designed to give back to you a bit of stability and control. After all, whether you're towing a boat, an RV trailer, ATVs or horses, you're supposed to be having fun!

For more towing tips and resources, please see the links on the next page.


Lots More Information

Related HowStuffWorks Articles
More Great Links:
  • The (Australian) National Caravan and Recreational Vehicle Towing Guide
  • National Highway Transportation Safety Administration: Towing a Trailer, Being Equipped for Safety
  • National Association of Trailer Manufacturers
  • Blue Ox. "Installation Instructions." (10/6/2008)
  • California Department of Motor Vehicles. "Towing Your Trailer Safely."(10/5/2008)
  • "Towing Tips, Specs, and Definitions." (10/6/2008)
  • "Choosing the Correct Ball Mount." (10/4/2008)
  • National Highway Traffic Safety Administration. "Towing a Trailer: Being Equipped for Safety."(10/7/2008)
  • Caravan and Camping Industry Association (Australia). "Towing Your Trailer." (10/7/2008)