They allow the load / unload of the material from the roller ways. The material is moved in a perpendicular direction respect the movement of the roller ways. For each roller way there is a cross field, formed by a certain number of single modules, called conveyors. The quantity of conveyors per field depends on the length of the material to be moved. These machinery also have the task of acting as buffer for the system; in fact it is possible to store more semi-finished products which will be loaded one at a time on the roller way. The operating principle includes an hydraulically lifter, which raises the bar and depose it in the desired position, moving along the length of the conveyors.