At the equilibrium position, {TAIL ~ the vent} and vent {HEAD ~ follower} are in direct relation to one another 
At the equilibrium position , { TAIL ~ the vent } and vent { HEAD ~ follower } are in direct relation to one another
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH