Abstract: A platform, for use in a sheet stacking device in which the platform descends as a stack being formed on it grows higher, is so constructed that its length can be varied according to the length of sheets to be stacked. The platform is made in two or more sections (10, 11, 12) each hinged (15, 17) to the next, and all sections are supported horizontally to receive long sheets, less than all the sections being horizontal and the remaining sections hanging vertically when shorter sheets are being stacked. Wheels (13, 16, 18) may be provided on the platform so that it may easily be moved out of the stacking device when loaded, all the sections being restored to a horizontal position for such movement.