The edge of the partial ball is characterized by having {HEAD ~ a v notch} to obtain {TAIL ~ desired valve characteristics} as well as to provide shearing actions at the sharp edges of the valve as it closes 
to obtain
The edge of the partial ball is characterized by having { HEAD ~ a v notch } to obtain { TAIL ~ desired valve characteristics } as well as to provide shearing actions at the sharp edges of the valve as it closes
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH