Trailer Terms Glossary

In trailering, there are tons of terms and phrases to learn. GVWR and OEM are mysterious acronyms for newbies, and the conversation can quickly become confusing. Whether you’re new to the world of trailers, or you’re in need of a refresher, you can consult our trailer glossary for basic definitions of common trailer terms.

ATV Trailer – These trailers are used to transport motorcycles, ATVs and other large objects.

Axle – A rod (fixed or rotating) that passes through the center of one or more wheels.

Ball mount – A receiver hitch accessory made of a shank and trailer ball platform.

Bearing protectors – Also known as bearing buddies. They replace the dust cap so that wheel bearings can be easily greased.

Bull-nose – Trailer with rounded front corners to provide additional swing clearance.

Bumper pull – a trailer that attaches to a hitch and ball connected to the tow vehicle’s frame or bumper.

Car hauler trailer – Also known as a car carrier trailer or auto transport trailer. A trailer designed to transport passenger vehicles. They can be open or enclosed, and often include built-in ramps.

Cargo trailer – Also known as an enclosed trailer. A trailer with a roof and walls fully surrounding the trailer’s contents.

Converter – Converts 3-wire tow vehicle electrical systems to 2-wire systems. Integrates the brake and turn signal circuits.

Coupler – The part of the trailer tongue that secures the tow vehicle to the hitch ball.

Cross members – Structural components that support the floor of the trailer.

Dump trailer – A trailer with high, solid walls to carry contents and a lifting mechanism to drop contents in a different location.

Dust cap – Covers the hub center to protect the greased wheel bearings from dirt and dust.

Flatbed trailer – An open deck trailer with no roof of sides. It is often used to transport large, heavy equipment.

Gooseneck – A trailer level with and connected to the bed of a truck.

Gross trailer weight – The total calculated weight of a trailer and its cargo.

GVW – Gross Vehicle Weight. The total weight of a unit including cargo and passengers.

GVWR – Gross Vehicle Weight Rating. The maximum amount of weight your trailer or vehicle can safely carry.

Hitch – A device to attach the tow vehicle to the trailer.

Hitch ball – The hitch attachment where a trailer coupler is connected.

Hitch bar – Also called ball mount or drawbar. A removable hitch ball platform. They can be used to raise or lower the hitch ball height before towing.

Hitch system rating – The maximum amount of weight you can safely haul with your towing configuration.

Hub – The part that connects the wheel and the wheel bearings.

Insert – Any part that slides into a receiver-style hitch.

Leaf springer – A spring made of several layers of flexible metallic strips joined together. They are arc-shaped with a rectangular cross section.

LED – Light-Emitting Diode. An energy efficient type of light bulb providing more light with less heat and electricity.

Locking pin – A pin locking one mechanism to another.

Lug nut – A large, rounded nut that fits over a heavy bolt. Often used to attach the wheel of a vehicle to the axle.

OEM – Original Equipment Manufacturer. This organization sells their products to a business, not directly to a consumer.

Payload capacity – The maximum amount of weight your vehicle can safely carry.

Pintle hook – The hooked part of the pintle hitch which attaches to the tow vehicle.

Pintle mount – An insert for a receiver hitch. It’s what the pintle hook is connected to.

Plug – It’s used to connect the trailer wiring to a tow vehicle.

Rear ramp door – A door on the back of the trailer. It’s hinged on the bottom and lowers to create a trailer ramp.

Receiver – The part of a trailer hitch that holds inserts, like ball mounts.

Safety chains – Chains attached to the trailer tongue with hooks on their free ends to keep the trailer connected to the tow vehicle if the coupler or hitch ball detaches.

Shackle – A flat piece of metal used to connect the leaf spring to the spring hanger.

Single axle trailer – A towing unit featuring a single axle. Two wheels are connected to the axle to allow the trailer to roll forward.

Snowmobile trailer – A trailer made to haul snowmobiles. They can be open, hybrid or enclosed.

Spindle – A rod that serves as the axis for two revolving hubs.

Spring bar – It helps distribute weight to keep your trailer in line with your vehicle. It has adjustable tension control, and can be tightened or loosened for weather conditions.

Spring hanger – A U-shaped piece of metal attaching the leaf spring to the frame.

Stacker trailer – A car trailer that allows cars to be loaded on lower and upper decks. It includes a lift to raise cars to the upper level. It can be found in gooseneck and bumper pull models.

Surge brake system – The self-contained braking system on the trailer that activates when the tow vehicle slows down.

Sway control device – A device to resist the swaying movement of a trailer.

Tandem axle trailer – Also known as a double axle trailer or dual axle trailer. It’s a trailer with two axles, one behind the other.

Tilt deck trailer – A trailer with hydraulic cylinders to ensure easy automatic tilting of the trailer bed.

Tongue – The part of the trailer that extends forward and includes the coupler.

Tongue weight – The force put on the hitch ball by the trailer coupler.

Tow vehicle – The vehicle that pulls the trailer.

Utility trailer – Also known as an equipment trailer or open trailer. A trailer designed to transport personal property, materials or equipment.

V-Nose – A trailer with a V shaped front. The section that attaches to the vehicle hitch.

VIN – Vehicle Identification Number. Unique to each vehicle.

Wheel bearing – A structural part of the trailer that supports the connection of the spindle to the hub. It reduces friction and wear.

Wheel grease – A thick oil used to lubricate the wheel bearings and extended wheel life.