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