Ball height – Measurements from the ground to the center of the hitch ball on the tow vehicle and to the center of the hitch-ball coupling on the trailer when the tongue is level with the ground.
Ball mount – Part of the receiver hitch system that supports the hitch ball.
Brake controller – Electronic device that applies power to the trailer’s electric brakes in proportion to the tow vehicle’s deceleration.
Breakaway switch – Safety device that automatically activates the trailer brakes should the trailer become disconnected from the tow vehicle.
Bunk trailer – Type of boat trailer that uses flat rails to support the boat.
Fifth-wheel hitch – Trailer coupling device mounted over the rear axle in the cargo bed. It’s so named because of the wheel-shaped hitch plate.
Gooseneck – Type of trailer with a long pivoted coupling arm that is attached to a large ball mount in the pickup bed. Gooseneck trailers usually can make tighter turns than a fifth-wheel trailer.
GCWR – Stands for Gross Combined Weight Rating. This is the manufacturer’s maximum allowable total weight of a towing vehicle plus a loaded trailer. The actual gross combined weight of a fully loaded towing vehicle and gross trailer weight must not exceed the GCWR.
Hitch ball – The sphere-shaped attachment point between the coupler on the trailer and the hitch.
Hydraulic surge brake – Type of brake used on boat trailers. It features a self-contained hydraulic system and lever-action coupler that activates the brakes when the tow vehicle decelerates.
Receiver hitch – Hitch design where a receiver subframe is attached to the vehicle frame. The hitch features a square opening that “receives” and secures the ball mount.
Roller trailer – Type of boat trailer that uses self-centering roller assemblies to support the boat.
Safety chains – Set of heavy-duty chains designed to help keep the trailer close to the tow vehicle if there is a hitch failure.
Shank – The removable portion of the hitch system that supports the hitch ball or adjustable ball mount. Also called hitch bar, drawbar, insert or stinger.
Spring bar – Critical part of the weight-distributing hitch system. When adjusted properly, spring bars act like handles of a wheelbarrow and transfer hitch weight to the vehicle and trailer axles.
Sway control – There are two types: mechanical and electronic. Mechanical includes friction or cam-action devices designed for the trailer to dampen yaw or fishtailing. The electronic version is a program in the vehicle’s stability control system that detects trailer yaw and applies pressure on selective brakes to help reduce the trailer sway.
Tongue weight – Weight of the trailer that rests directly on the hitch ball. May also be called hitch weight. Recommended tongue weight is about 10% of the trailer weight for conventional hitches and up to 25% of the trailer weight for fifth-wheel and gooseneck hitches.
Tow rating – Vehicle manufacturer’s maximum allowable trailer weight.
Weight carrying hitch – Type of hitch system where the entire tongue weight of the trailer is supported by the hitch ball and transferred to the rear axle of the tow vehicle.
Weight distributing hitch – Type of hitch system that uses spring bars to spread a portion of the trailer tongue weight to all the axles of the tow vehicle and trailer.