CouplerIt latches onto the ball on the tow vehicle. The two can then pivot as they go over bumps.
A-frame tongueSome of the trailer's weight rests on the tow vehicle through it. That part is called tongue weight.
Tongue jackIt raises and lowers the tongue. The coupler can then be set on the ball or lifted off.
Safety chainsThey keep the trailer attached if the coupler comes loose. They hook to the tow vehicle.
Breakaway switchThe cable pulls a pin from it if the trailer comes uncoupled. The trailer's own battery then applies its brakes.
Outside of the box 10
V-noseSeen from above the front comes to a point like a V. From the side it shows as a narrow front panel.
Stone guardIt guards the front of the box against stones and road debris.
Side doorA way in without opening the back. Makers also call it the side entry.
Sidewall ventIt lets air flow through the box.
Roof ventA vent set in the roof to air the box.
Clearance lightsChecked before each tow. So are the tail lights, stop lights and turn signals.
FenderIt covers both wheels on this side. It is not part of the frame and is not made to be stood on.
Tandem axlesEach axle has a weight rating. The load on it should never go over that rating.
Rear corner postsThe frame posts at the two rear corners. One stands on each side of the door opening.
Tail lightsChecked before each tow, with the stop lights and turn signals.
Ramp door 4
Ramp doorHinged along the bottom and lowered to the ground for loading. It is latched shut before towing.
Ramp flapAn extension flap on the end of the ramp door.
Ramp cablesWith the spring they carry part of the ramp door's weight. They do this as it goes down and up.
Torsion springIt counterbalances the ramp door. That makes the door easier to raise and lower.
Inside the box 5
Wall studsThe upright tubes of the wall frame, set at even spacing. Also called wall posts.
Roof bowsThe cross members of the roof frame, spaced along the box.
FloorHeavy items are loaded on the floor, over the axles.
E-trackStraps and cargo bars clip into it to hold the load.
D-ringsTie-down points for straps. Each is a ring on a plate fixed to the floor.
How this list was compiled: Part names checked on 2026-09-30, a name kept only when two independent makers use it. (1) Haulmark (American Cargo Group): Owner's Manual, 11-2025, https://haulmark.com/images/pdfs/specifications/Haulmark_Owners_Manual_11-2025.pdf (coupler, safety chains, breakaway switch, jack and tongue jack, tongue A-frame, drop ramp door, spring and cable counterbalance, torsion spring assembly, wall posts, roof bows, corner posts, fenders, floors, vents, stone guard, E-track, tandem axle) and its Transport V-Nose cargo trailer page, https://haulmark.com/trailers/cargo-trailers/transport/transport-v-nose (V-nose, stoneguard, flow-thru sidewall vents, side door, rear ramp door with spring assist, ramp extension, D-rings, fenders, clearance lights, tail lights, tube vertical posts, roof vent, E-track on sidewall). (2) LOOK Trailers (Novae): Owner's Manual, 2020, https://looktrailers.com/wp-content/uploads/2025/03/LOOK_Owners_Manual-2020.pdf (coupler, safety chains, breakaway switch, tongue jack, A-frame or tongue, drop-ramp door with torsion spring and cable, fenders, roof vents, clearance lights, taillights, axles, floor) and its cargo trailer pages, https://looktrailers.com/series/st-dlx-cargo-trailer/ , https://looktrailers.com/series/lxt-cargo-contractor-trailer/ and https://looktrailers.com/series/vision-aluminum-cargo-trailer/ (V-nose, stoneguard, side entry, rear ramp door, extension flap, sidewall vents, wall studs, roof bows, rear corner posts, flooring, D-rings, wall E-track). Wikipedia, Trailer (vehicle), was read for the coupler and the jack. The Haulmark glossary of trailer terms, https://haulmark.com/haulmark-resources/trailer-terms , gave tongue weight and the axle rating. Licence: own work
The drawing: Drawn for this site on 2026-09-30 from plain geometry; no maker's trailer, nothing traced. Licence: own work
How it works
An enclosed cargo trailer is a box on a frame: a tongue and coupler in front, one or two axles under it, and a rear door, here a ramp. The second view looks inside.
Read the full guide
Side first, then look in from behind
The side view names what you check before towing: the coupler on the ball, the safety chains, the breakaway switch cable, the tongue jack wound up, and the lights. The rear view has the ramp door down. The left wall is drawn without its lining, so the wall studs show, and the roof bows cross the ceiling above them.
Heavy items go on the floor, over the axles.
This page names the parts; it does not sell them.
Questions and answers
What are the parts of an enclosed cargo trailer?
Outside: the coupler, tongue, tongue jack, safety chains, fenders, axles, side door, vents and lights. At the back: the ramp door with its cables and torsion spring. Inside: wall studs, roof bows, the floor, and tie-downs such as D-rings and E-track.
What is the front of a cargo trailer called?
The frame reaching forward is the tongue, or A-frame, and the coupler sits on its tip. The front wall of the box is the nose; one that comes to a point is a V-nose.
What does a breakaway switch do on a trailer?
If the trailer comes uncoupled, a cable fixed to the tow vehicle pulls a pin out of the switch. The trailer's own battery then applies the trailer brakes.
What is E-track in a cargo trailer?
A rail fixed along the wall of the box. Straps and cargo bars fasten to it to hold the load in place. Makers list it as an option, alongside D-rings, which are tie-down rings in the floor.