{HEAD ~ A spring} is supported on the counterholder and is intended for prestressing {TAIL ~ a closing part} against a valve seat 
is intended for prestressing
{ HEAD ~ A spring } is supported on the counterholder and is intended for prestressing { TAIL ~ a closing part } against a valve seat
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH