Abstract: An internal loading cylindrical air filter apparatus having a circular tubular knit pile fabric filter element extending unsupported between end plates to provide an essentially full length unobstructed filter area, and having a rotating internal suction cleaning nozzle therefor. The tubular filter element is supported at its entry end by a detachable angle ring having a cylindrical ring flange extending through an opening in the entry end plate of the apparatus to permit endwise assembly and disassembly of the fabric filter element into the apparatus. Annular or helical strands may extend in circumferential engagement with the filter element for restraining it from ballooning out of effective cleaning distance with respect to the rotating suction nozzle under heavy filtering conditions, and a crank may be provided for adjusting the extending length of a helically extending restraining strand for controlling the degree of restaint imposed on the filter element.