The center roller and {HEAD ~ the first edge roller} are rotatably supported on {TAIL ~ a common axis} 
rotatably supported on
The center roller and { HEAD ~ the first edge roller } are rotatably supported on { TAIL ~ a common axis }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL