Variable diameter drum

Claim 1

A variable diameter drum comprising: a rotating shaft; a plurality of separate cylinder segments circumferentially arranged around the shaft and each having an outer arc surface and outwardly beveled upper and lower surfaces such that lines extended parallel to said upper and lower surfaces would meet above said outer arc surface, the outer arc surfaces of said cylinder segments forming a substantially continuous cylindrical surface when said cylinder segments are joined together; means for holding said cylinder segments, but allowing said cylinder segments to translate in their radial directions, said holding means including a lower ring secured to the shaft and an upper ring mounted for axial motion on the shaft and biased toward the lower ring, said cylinder segments being interposed between the lower and upper rings, said lower ring having an inwardly bevelled upper surface mating with said outwardly bevelled lower surfaces of said cylinder segments, and said upper ring having an inwardly bevelled lower surface mating with said outwardly bevelled upper surfaces of said cylinder segments; and means for adjusting the position of said cylinder segments in their radial directions.