In addition, each drive roller has its own drive motor so it can be driven independently in {TAIL ~ either direction} about {HEAD ~ the common axis} 
In addition , each drive roller has its own drive motor so it can be driven independently in { TAIL ~ either direction } about { HEAD ~ the common axis }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD