Rotary brush

A brush assembly adapted to be rotated about an axis, the assembly comprising:

• a brush having
• a flexible, annular and generally cylindrical collar generally centered on the axis and having a predetermined and generally uniform radial thickness, a predetermined inside diameter, and a predetermined axial length, and
• a plurality of arrays of radially projecting bristles angularly equispaced about the collar and defining a plurality of axially throughgoing and angularly equispaced bristle-free zones;
• a holder drum having
• a core generally coaxially surrounded by the collar, having a generally cylindrical outer surface centered on the axis and having a predetermined outside diameter substantially smaller than the inside diameter of the collar,
• inner and outer end flanges axially flanking the core and spaced axially apart by a predetermined axial distance greater than the axial length of the collar, whereby the collar is received with axial play between the flanges, and
• respective retaining tongues extending axially between the flanges in the bristlefree zones of the brush radially outside the collar, the tongues having inner surfaces spaced radially outward from the cylindrical outer surface of the core by a radial spacing substantially greater than the radial thickness of the collar, whereby the collar is received with radial play between the outer surface of the core and the inner surfaces of the tongues and is adapted to bulge radially outward between the tongues when the assembly is rotated at high speed, the holder drum being formed by a pair of identical parts each forming a respective one of the flanges, half of the core, and half of each of the tongues;
• and
• means for releasably securing the parts axially together.