wherein said front face portions and said rear face portions form inclined curved face portions on both peripherial ends of said front and rear face portions to form {HEAD ~ hydrodynamic bearing face portions} for {TAIL ~ multidirectional movements} of said piston shoes, 
for
wherein said front face portions and said rear face portions form inclined curved face portions on both peripherial ends of said front and rear face portions to form { HEAD ~ hydrodynamic bearing face portions } for { TAIL ~ multidirectional movements } of said piston shoes ,
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH