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