To surely prevent rocking of an overturning prevention piece even when an external force is applied to the overturning prevention piece in a developed state.
A link mechanism 20 is provided that rocks the overturning prevention piece 13 downwardly overhanging when a deck is elevated and stored in a storing position when the deck is lowered, and that interlocks with the elevation/lowering of the deck. Protrusions 27 and recessed parts 28 engaging with each other at the developed position are provided to first and second links 21, 22 composing the link mechanism 20, and a given play is set to the connection part of the first and the second links 21, 22, thus, when an external force is applied to the overturning prevention piece 13, the protrusions 27 and recessed parts 28 are engaged with each other for rocking in any direction, while, when the first link is rocked by the lowering of a pressing rod 11b, the operation of the second link 22 is delayed till the protrusion 27 is released from the recessed part 28, to prevent the protrusion 27 and the recessed part 28 from disturbing storing of the overturning prevention piece 13.
KAWASAKI TAKESHI
IGARASHI NORIHIDE
