Towing Glossary

This is a list of terms that are related to towing and hitches. We have created sections based on the part of your towing configuration that the term relates to.

Also be sure to check our towing tips or call 1-800-BE4-U-TOW if you need further assistance.

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A trailer hitch is a device which attaches directly to a tow vehicle providing the connection between the tow vehicle and the trailer.Hitch installations are most often considered permanent. A fixed tongue hitch includes a flat non-removable drawbar, while a receiver style hitch has a receptacle (typically 1-1/4" or 2") for inserting special ball mounts or bike racks.

Also see: custom hitch, fixed tongue hitch, permanent undercar hitch, receiver style hitch, and round tube hitch.

Hitch System Rating

This is the maximum weight you can tow with your configuration. A hitch system is only as strong as its lowest-rated component.Compare the maximum tow weight ratings of your hitch, ball mount and hitch ball. Your hitch system rating is the lowest weight rating among those components.

For more instructions about finding your hitch system rating, watch the video to the right or read our hitch system rating tutorial.

When determining how much you can tow, it is also important to consider the maximum tow weight of your vehicle. Check your vehicle's manual or contact the manufacturer for this information.

After you have determined the max your vehicle can tow, you must select the proper equipment.The two most important factors in selecting towing equipment are gross trailer weight and tongue weight.

Hitch Types

Bolt-on trailer hitch (permanent undercar trailer hitch)
Diagram of a properly mounted hitch A device which attaches directly to the tow vehicle providing the connection between the tow vehicle and the trailer.A fixed tongue hitch includes the ball platform, while a receiver style hitch has a receptacle (typically 1-1/4" or 2") for inserting special ball mounts or bike racks.
Custom trailer hitch

A hitch that is designed for a particular year, make and model of vehicle. Because these hitches are made for a specific vehicle, the best possible appearance can be achieved.

Also see: hitch, fixed tongue hitch, permanent undercar hitch, receiver style hitch, and round tube hitch.
Fifth wheel hitch
A Class 5 trailer hitch that mounts in the bed of pickup truck which uses a plate in the bed of the truck (similiar to a semi-tractor) and a pin on the trailer.
Fixed tongue hitch

A trailer hitch with an integral ball platform (tongue) that cannot be removed.

Also see: custom hitch, hitch, permanent undercar hitch, receiver style hitch, and round tube hitch.
A Class 5 hitch that mounts a ball in the bed of a pickup truck(either 2-5/16" or 3" in diameter) to engage a coupler on a trailer. Not to be confused with a fifth wheel.
Original equipment manufacturer parts are manufactured by the same people who made your vehicle.
Pintle hitch
A common heavy-duty coupling type which utilizes a pintle hook attached to a tow vehicle to pull a trailer having a lunette eye. Pintle hitches are commonly used on military, construction, industrial and agricultural equipment.
Receiver style hitch

Any hitch with a receptacle (typically 1-1/4" or 2") which accommodates inserts such as drawbars, ball mounts, or bike racks.

Also see: custom hitch, fixed tongue hitch, bolt-on hitch , hitch, and round tube hitch.
Round tube hitch
A new generation of custom hitches designed to produce a more pleasing visual appearance. The use of round tubing lowers the weight of the hitch while maintaining its strength. These hitches are designed to compliment the look of the vehicles for which they are made.
Weight carrying hitch
Any hitch used without a weight-distributing system. Some hitches are designed and clearly marked "weight carrying only". Some hitches are weight carrying with weight distributing ability and will have a dual rating – "weight carrying(WC) 5000/weight distributing(WD) 10,000", for example. To use a hitch at the higher rating(WD), a weight distribution system must be added. 

Hitch Parts

See Hitch Ball.
Ball mount

A removable hitch ball platform that slides into the receiver of a hitch and fastens with a pin and clip. Different ball mounts can be used to raise or lower the height of the ball to allow for level trailer towing. Ball mounts are available online at the U-Haul Store.

Also see: Drawbar
Converts 3-wire tow vehicle electrical systems to 2-wire systems by integrating the stop and turn signal circuits as is common in trailer wiring.

A removable coupling platform that slides into a hitch receiver and fastens with a pin and clip, or the "tongue" portion of a fixed-tongue hitch. The term drawbar is sometimes used to distinguish a non-adjustible (solid shank) ball mount or a coupling configuration different than a hitch ball (such as a pintle hook).

Also see: Ball Mount
Hitch ball
The ball-shaped attachment to a hitch onto which a trailer coupler is attached. Hitch balls are available online at the U-Haul Store.
Hitch bar
See ball mount or drawbar
Any item that slides into a receiver style hitch (i.e. ball mount, bike rack, winch).
Locking pin
A hitch pin that locks with a key to prevent theft of a ball mount or other insert.
Used to fasten any insert (ball mount, bike rack) into a receiver hitch. Available in standard and locking configurations.
Pintle hook
The "jaw" portion of a pintle hitch which attaches to the tow vehicle.
Pintle mount
An insert for a receiver hitch, having a shank with a flat plate to bolt a pintlehookto. These mounts are typically adjustable for vertical height.
The connector used to connect trailer wiring to a tow vehicle.
The receptacle part of a trailer hitch which accommodates inserts such as ball mounts, drawbars or accessory carriers. Common receiver sizes are 1-1/4" and 2".

Hitch Measurements

Class 1 (Class I) trailer hitch
Trailer hitch with capacity of up to 2,000 lbs gross trailer weight and 200 lbs tongue weight.
Class 2 (Class II) trailer hitch
Trailer hitch with weight-carrying rating of up to 3,500 lbs gross trailer weight and 300/350 lbs tongue weight.
Class 3 (Class III) trailer hitch
Trailer hitch with weight carrying rating of up to 5,000 lbs gross trailer weight and 500 lbs tongue weight. Also sometimes used to refer to a hitch with any 2"receiver, regardless of rating.
Class 4 (Class IV) trailer hitch
Trailer hitch with weight carrying rating of up to 10,000 lbs gross trailer weight and 1,000-1,200 lbs tongue weight. Although many times any hitch with a capacity greater than 5,000 lbs gross weight is referred to as a Class 4.
Ball height
Distance from the ground to the center of the hitch ball or hitch ball coupling (trailer) when parked on a flat surface and parallel to the ground. Used to determine the amount of drop or rise needed in the ball mount to make the trailer ride parallel to the ground when being towed. The maximum recommended hitch ball height for U-Haul trailers is 25" from the ground measured to the center of the hitch ball.
Hitch weight
See Tongue Weight
A minimum testing/rating system of trailer hitches established by the Trailer Hitch Manufacturers Association.

Optional Hitch Add-ons

See weight distribution system.
Receiver cover
A temporary receiver end-cap insertable into a 1-1/4" or 2" hitch receiver. Designed to protect from the elements. Also used to mask or enhance the look of the hitch when not in use.
Spring bar
Key component of a weight-distributing hitch system. Spring bars work to distribute trailer tongue loads to the tow vehicle forward axle.
Sway control device
A device similiar to a shock absorber which resists swaying movement of a trailer tongue sometimes caused by passing vehicles and wind.
Weight distribution system
A hitch system built around a receiver hitch, which includes supplemental equipment such as spring bars that work to distribute trailer tongue loads to the trailer axle(s) and the tow vehicle front axle. Use of weight distribution system enhances handling and braking and increases trailer towing capacity beyond what is recommended when a weight-carrying hitch is used.

Tow Vehicle

The tow vehicle (towing vehicle) is the vehicle that pulls a trailer or towed vehicle.


All-wheel drive
Your vehicle has all wheel drive (AWD) if all four wheels receive power from the engine. This includes four wheel drive(4WD) vehicles.
Front-wheel drive
Front-wheel drive (FWD) vehicles have power only going to the front wheels. Most sedans and vans fall into this category.


Curb weight
The empty weight of a vehicle full of fuel and all fluids. Curb weight does not include passengers or payload.Your vehicle's curb weight should be listed in its manual.
Gross vehicle weight (GVW)
The total weight of a vehicle including all of its contents and passengers.
Gross vehicle weight rating (GVWR)
The weight specified by a manufacturer as the recommended maximum weight of a vehicle when fully loaded.


Diagram of a rear tow bumper The parts on a vehicle that protect the front and rear ends in the event of an accident. Some trucks and SUVs have a tow bumper(or step bumper) for attaching a hitch ball for towing.
The main structure of a vehicle, which all other parts attach to.
Hard top
A metal or fiberglass rigid structure that fastens to a vehicle and encloses the occupant compartment.
Roll pan
A fascia panel used in place of a rear bumper (common on lowered trucks). Installation of a roll pan may interfere with placement of a bolt-on hitch.
Transmission cooler
An auxiliary cooler that is available to provide extra cooling for automatic transmission fluid. Lower temperatures equal longer transmission life. Transmission coolers are available online at the U-Haul store.

Trailer or Towing Device

These terms apply to the trailer or anything else being towed including another vehicle


Tandem axle
Two axles (four wheels).


Gross trailer weight (GTW)
The weight of the trailer fully loaded in its actual towing condition. Check out how to determine gross trailer weight & tongue weight capacities.
The transported load, freight, excluding the weight of the trailer or tow vehicle.
Tongue weight

The downward force exerted on the hitch ball by the trailer coupler. In most cases, it is about 10 to 15 percent of the GTW. To tow safely, the tongue weight must be sufficiently positive when the trailer is empty and/or when fully loaded. Check the height of the tow vehicle's bumper before and after loading. If the loaded trailer doesn't drop the height of the bumper by at least another inch, then reposition your load with more weight in the front of the trailer. Check out how to determine GTW& TW capacities.

Also see: weight distribution system.


handwheel The threaded turnable wheel on top of a U-Haul trailer coupler that tightens or loosens the coupler assembly around the hitch ball.
coupler The forward-most part of a trailer tongue that envelopes and secures to the tow vehicle hitch ball.
Safety chains
The chains that are attached to the trailer tongue with hooks on their free ends. These chains keep the trailer connected to the tow vehicle should the coupler or hitch ball detach from the tow vehicle. Safety chains must be secured every time you tow.
Surge brake system
A surge brake system is entirely self-contained on the trailer and is activated when the tow vehicle decelerates. The momentum of the trailer pushes the surge brake housing forward. This drives the push rod that is connected to the coupler into the master cylinder. Brake fluid is then forced out of the master cylinder into the wheel cylinders or pistons that apply the trailer brakes. The entire activation process is completed in less than one second. Hydraulic surge brake systems can be used by a variety of tow vehicles and can accommodate a variety of trailer loading conditions without requiring any type of adjustment. All U-Haul braked trailers use a surge brake system.
Diagram of a trailer providing the position of the tongue The part of the trailer which extends forward from the trailer box and includes the coupler.
Tow bar
A device attached to the front of a vehicle which allows it to be towed by another vehicle while riding on its own wheels.

Terms that apply to the entire hitch system

Brake controller
Neccessary for the use of electric trailer brakes. Synchronizes trailer braking to the tow vehicle.
Gross combined vehicle weight (GCVW)
Total combined weight of your vehicle and the trailer or towing equipment, including all passengers and payload.
Diagram of a vehicle towing a trailer in a jackknife position An extreme turning manuever that risks damage to the tow vehicle and the trailer when the trailer tongue or body swings into the contact with the tow vehicle. Jackknife accidents usually occur while backing up.
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