Towing Glossary

Ball
See Hitch Ball.


Ball height
Measurement 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.


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.
Also see: Drawbar


Bolt-on hitch (permanent undercar 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.


Brake controller
Interface between tow vehicle and electric trailer brakes. Can be inertia activated or based on time delay from activation of vehicle brakes. Typically in the tow vehicle's driving compartment with electrical line running to the trailer wiring connector. Most require the user to adjust brake gain to compensate for varying trailer load. Necessary for the use of electric trailer brakes.


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.


Chassis
The main structure of a vehicle, which all other parts attach to regardless whether it is unibody or frame construction.


Class 1 (Class I) hitch
Trailer hitch with capacity of up to 2,000 lbs. gross trailer weight and 200 lbs. tongue weight.


Class 2 (Class II) 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) 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) 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.


Converter
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.


Coupler
The forward most part of a trailer tongue that envelopes and secures to the tow vehicle hitch ball.


Curb weight
The empty weight of a vehicle full of fuel and all fluids. Curb weight does not include passengers or payload.


Custom 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.


Drawbar
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 ball mount with a solid ball shank or a coupling configuration different than a hitch ball (such as a pintle hook).
Also see: Ball Mount


Equalizer
See weight distribution system.


Fifth wheel hitch
A Class 5 hitch that mounts in the bed of pickup truck which uses a plate in the bed of the truck (similar to a semi-tractor) and a pin on the trailer.


Fixed tongue hitch
A 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.


Gooseneck
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.


Gross combined vehicle weight (GCVW)
Total combined weight of the two coupled vehicles, including all passengers and payload.


Gross trailer weight (GTW)
The total weight of a trailer including all of its contents.


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.


Handwheel
The threaded turnable wheel on top of a trailer coupler that tightens or loosens the coupler assembly around the hitch ball.


Hitch
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, receiver style hitch, and round tube hitch.


Hitch ball
The ball-shaped attachment to a hitch onto which a trailer coupler is attached.


Hitch bar
See ball mount or drawbar


Hitch weight
See Tongue Weight


Insert
Any item that slides into a receiver style hitch (i.e. ball mount, bike rack, winch).


Jackknife
An extreme turning maneuver 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.


Locking pin
A hitch pin that locks with a key to prevent theft of a ball mount or other insert.


Lunette eye
A round metal ring used in place of a ball coupler on a trailer. It attaches to a pintle hook on the towing vehicle.


Pin
Used to fasten any insert (ball mount, bike rack) into a receiver hitch. Available in standard and locking configurations.


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.


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 pintlehook to. These mounts are typically adjustable for vertical height.


Plug
The connector used to connect trailer wiring to a tow vehicle.


Receiver
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".


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.


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.


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.


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.


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.


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 similar to a shock absorber which resists swaying movement of a trailer tongue sometimes caused by passing vehicles and wind.


Tandem axle
Two axles (four wheels).


Tongue
The part of the trailer which extends forward from the trailer box and includes the coupler.

 


Tongue weight
The downward weight applied by the towable equipment on the hitch ball. Generally tongue weight should not be more than 10% of the gross trailer weight.
Also see: weight distribution system.


Tow vehicle (towing vehicle)
The vehicle that pulls a trailer or towed vehicle.


V-5
A minimum testing/rating system of trailer hitches established by the Trailer Hitch Manufacturers Association.


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. 


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.