Axial forces acting on the check are balanced during movement between the sealing and open positions so that {HEAD ~ direct control} over the check position may be accomplished through {TAIL ~ the use} of a low force actuator 
Axial forces acting on the check are balanced during movement between the sealing and open positions so that { HEAD ~ direct control } over the check position may be accomplished through { TAIL ~ the use } of a low force actuator
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH