US Patent 7135109 Filter screen assembly

A fine filter screen assembly includes a frame assembly and a rotatable shaft supported in the frame. A drive is configured to controllably rotate the shaft and at least one drive drum is positioned on the shaft for rotation therewith. The drive drum has an external surface that is substantially defined by a high friction surface and a fine filter grid is supported in the frame assembly and positioned about and in contact with the drive drum such that rotation of the shaft causes rotation of the fine filter grid.