The invention relates to a transport wagon for receiving cargo, particularly made of agricultural harvest products, such as bales pressed from straw or silage. Such wagons comprise a loading platform, which extends beneath the cargo and is delimited by longitudinal and lateral side parts, wherein the transport chamber is accessible, particularly when the longitudinal side walls are opened. According to the invention, at least one of the longitudinal side walls is provided with a support device, by means of which the longitudinal side wall can be displaced from an open position close to the ground into a closed position, in which it captures at least one upper layer of the stacked cargo and secures it laterally.