Tray - load and unload, up and down the up-down material for typical agency: institutions include servo motor, screw module, slippery course sliding block, a similar gantry structure promote pallet rack up and down, while the tray pallet rack stacked on top and bottom, the agency for the whole module, call to the machine as the material, can also be used as the material stack, as the most classic and institution.The machine should be designed to use the model.if you like,you can paypal for you to get this models or if you have any questions also you can email to me.