Towing Glossary


Affixed to the trailer tongue, the coupler is the round, hollowed portion that fits over the hitch ball.

Gross Trailer Weight (GTW)

The weight of the trailer plus all the cargo in it. This is measured by putting a fully loaded trailer on a scale. Should never exceed gross trailer weight rating.

Gross Trailer Weight Rating (GTWR)

Maximum allowable weight of the trailer and its cargo. Defined by trailer manufacturer.

Hitch Ball

The steel ball bolted through the hitch head. (Not included in hitch purchase) Make sure your hitch ball is rated high enough for your towing requirements.

Hitch Receiver

Located under tow vehicle bumper, the hitch receiver permits the insertion of the hitch shank. Usually bolts to the tow vehicle frame. Look on receiver and/or owners manual for rating. For safe towing, never exceed rating.

Trailer Tongue Weight

The downward force exerted on the hitch ball by the trailer coupler. In most cases, it should not be less than 10 percent of the trailer load or more than 15 percent. Measured by placing uncoupled tongue jack foot along on a scale.

Weight Distributing Hitch

A weight-distributing system includes a shank attached to the tow vehicle receiver, plus a hitch head, spring arm assembly (sometimes called sping bar assembly), and brackets that connect to the trailer frame.


Inserts into the tow vehicle receiver and connects to the hitch head.

Sway Control Bracket

Equal-i-zer® and E2™ brackets bolt on to the trailer frame. The spring arms rest on the bracket creating steel on steel friction sway control.

Spring Arms

Set of solid steel square bars included in the hitch assembly that connect to the hitch head and the brackets.


Rectangular steel tubes on the Equal-i-zer® hitch head where the spring arms are inserted.

Linear Friction

Steel on steel positive friction created at the connection point of the spring arm on the L-bracket. Provides integrated sway control.

Rotational Friction

Downward pressure from the trailer tongue and upward pressure from the spring arms, created at the connection where head sockets rotate inside hitch head. Provides integrated sway control.

4-Point Sway Control™

Consists of the two points of rotational friction and two points of linear friction; works to combat trailer sway, such as fish tailing. Found exclusively in The Original Equal-i-zer® Sway Control Hitch.

2-Point Sway Control™

Utilizes the two points of linear friction from the sway control brackets to prevent trailer sway. Found on the E2™ hitch.

Weight Distribution

Helps distribute weight over the axels of the tow vehicle and trailer. Keeps tow vehicle and trailer from sagging at the center (coupler).

Trailer Classes -

   2,000-lb. gross trailer weight (trailer and cargo combined)
   Folding camping trailers and trailers for small boats, motorcycles and snowmobiles

   2,001-3,500-lb. gross trailer weight
   Single-axle, small- to medium-length (up to 18 ft.) trailers

   3,501-5,000-lb. gross trailer weight
   Dual-axle or large single-axle travel trailers
   Weight distribution and sway control should be considered

   Over 5,001-10,000-lb. gross trailer weight
   Largest travel and fifth-wheel trailers made for recreation
   Weight distribution and sway control is recommended

   Over 10,000-lb. gross trailer weight

*Disclaimer - All hitch definitions are based on Equal-i-zer® and E2™ hitches.

*Some terms and definitions referenced from the Ford and Dodge web sites.


How did Equal-i-zer do? FANTASTIC!! The difference in the ride, control, sway and driveability was phenomenal! I was very nervous driver before, but thanks to the Equal-i-zer I can just sit back and relax, like you are supposed to on a vacation. Thank you!!

~ Dorman L. (Pennsylvania)