Equipment / Trailers
Lowboy in trucking
Plain-English explanation
A lowboy is a specialized flatbed trailer with an extremely low deck height — typically 18-24 inches off the ground — designed to carry tall or very heavy equipment that would exceed standard height restrictions on a regular flatbed. Construction equipment such as excavators, bulldozers, scrapers, and large industrial machinery moves regularly on lowboys. The low deck height is achieved by a structural drop in the trailer frame after the gooseneck that connects to the tractor's fifth wheel. The main deck is much lower than the gooseneck section, which allows tall cargo to ride low enough to stay within the standard 13'6" height clearance limit — or to minimize how far above it a permitted oversize load extends. Most lowboys have detachable goosenecks (RGN — removable gooseneck): the front of the trailer detaches and drops to the ground, allowing equipment to be driven or winched directly onto the trailer under its own power. This eliminates the need for a crane or ramps to load. Lowboy loads frequently require oversize permits because equipment dimensions exceed standard height, width, or weight limits even on a lowboy. Permit routing must be pre-planned, checking bridge clearances, weight restrictions, and state-specific regulations. Escort vehicles ("pilot cars") are often required.
Equipment terms are best read physically: what is on the tractor, what trailer is assigned, how the freight loads, and what the driver can inspect before rolling.
Why it matters in trucking
Lowboys enable the movement of equipment that cannot be broken down or modified — an excavator or bulldozer ships as-is, and the trailer must accommodate it. Carriers who run lowboys deal with a different set of operational requirements than van or flatbed carriers: permits, pilot cars, routing restrictions, and highly varied loading and securement needs.
The right equipment term helps prevent the wrong truck from being sent to pickup, especially for reefer, flatbed, liftgate, power-only, or drop-trailer work.
Example in real use
A contractor needs a 65,000-pound excavator moved 340 miles. The excavator stands 11'2" with the bucket in transport position. On a standard flatbed (4'6" deck), total height is about 15'8" — well over the 13'6" limit. On a lowboy with a 20-inch deck, total height is about 13'2" — within standard limits without an oversize permit. The contractor arranges a lowboy carrier and the move is legal without a height permit, though a weight permit is still needed for the 65,000-pound equipment plus trailer weight.
Where it shows up
Lowboy details show up on heavy equipment moves, tall machinery, permit planning, and jobsites with special loading needs.
What to check first
- Exact dimensions and weight of the equipment.
- Deck height, axle setup, and capacity.
- Permit, escort, route, and travel-time restrictions.
- Loading and unloading method at both ends.
Common mistakes or confusion
- Assuming a lowboy can handle any heavy equipment without checking height, width, and weight against permit requirements — even a lowboy has height and weight limits above which permits, routing restrictions, and escort vehicles apply.
- Not confirming loading and unloading arrangements before dispatching a lowboy — RGN loading requires a clear flat area in front of the trailer for the gooseneck to detach and drop; not every site has that.
- Underestimating transit time for permitted oversize loads — permits may specify allowed travel hours, prohibited days, and required inspection stops that add significant time to the trip.
Related terms
Related guides
Truck Parts and Equipment Terms is the best next place to keep learning this topic.
Sources and last updated
Last updated: 2026-05-09