Driving elements maintain {HEAD ~ oscillating tangential vibrations} of {TAIL ~ the masses} about the z axis 
of
Driving elements maintain { HEAD ~ oscillating tangential vibrations } of { TAIL ~ the masses } about the z axis
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH