An axle useable in a disc or star separator screen for waste includes a rotation shaft defining a longitudinal axis, a plurality of discs or stars integrally coupled with the rotation shaft, and a plurality of anti-clogging sleeves mounted idle on the rotation shaft, each of the anti-clogging sleeves being interposed between a respective pair of consecutive discs or stars. Each anti-clogging sleeve has a first rotating element and a second rotating element arranged adjacent to each other, at least one of which is a tubular body. The rotating elements are mounted idle on the rotation shaft so as to rotate independently with respect to each other.