Abstract: A conveyor system for automatically orienting a majority of tobacco leaves received thereby in a lengthwise direction so that their stems are substantilly parallel to a final direction of conveyance. Tobacco leaves to be oriented are delivered by means of a high speed belt to a pneumatic processing apparatus in the form of a rotary screen assembly. The rotary screen assembly includes a broad perforated or open meshed screen which is driven in a downward and preferably vertical direction at its front side. The rotary screen is mounted adjacent and operatively coupled to a device for generating an air current through the screen such that the air holds articles to be oriented on the front side of the screen while being conveyed thereby. A take-off conveyor is mounted vertically below the rotary screen for receiving articles therefrom.