flatbed

[flat-bed]

noun

Also called flatbed trailer, flatbed truck. a truck or trailer having an open body in the form of a platform without sides or stakes.Compare stake truck.
flatbed scanner.

Origin of flatbed

1870–75, for an earlier sense; flat¹ + bed

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

In Donetsk it is presumed to have been off-loaded from the flatbed and started to move in a convoy on its own.
MH17 Missile Can't Hide From These Internet Sleuths
Eliot Higgins
August 2, 2014
Flatbed trucks have been spotted carrying tanks toward Gaza.
War in Gaza Poses Risks for All Sides
Dan Ephron
November 16, 2012

The two horses pulling the wagon, a flatbed with railed sides, halted at the creek.
Shaman
Robert Shea