Towing Glossary

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.


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

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 alone 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® brackets bolt onto the trailer frame. The spring arms rest on the L-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. Used to generate weight distribution, and contribute to the Integrated Sway Control (see Linear Friction).


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.

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

CLASS I - LIGHT-DUTY - 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