To efficiently keep an article and to effectively use the same as an aging chamber by raising an article feed palette to selected height or lowering the same therefrom when a hook is closed and bringing the palette to a state capable of being engaged with a set of corresponding step when the hook is opened.

A pair of Z-beams 36 are raised to the same height as a conveyor section to be taken up by a hook. A moving bridge 52 is moved to a green block conveyor 14 to bring the Z-beams 36 into engagement with the underside of a feed palette P. A hoisting mechanism block is raised to be housed, in the moving bridge 52 and moved to be allowed to fall above a selected well 37. During falling, the hook is perfectly closed and the Z-beams 36 pass without being stopped at a step part 34. The hoisting mechanism block stops at a selected accurate position and the hook is opened up to an intermediate position to move the Z-beams 36 to the step 34 and the hook is perfectly opened and the hoisting mechanism block is moved to the uppermost part to be perfectly housed in the moving bridge 5.