The machine includes a rotatable drum having {HEAD ~ a spaced pair} of {TAIL ~ cylindrically contoured surfaces} 
of
The machine includes a rotatable drum having { HEAD ~ a spaced pair } of { TAIL ~ cylindrically contoured surfaces }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL