whereby said piston shoes form {HEAD ~ multidirectional hydrodynamic bearing shoes} for forewards and rearwards directed movements of said piston shoes by said curved face portions with said bearing face radii by the extension of said curved face portions equally symmetrical in both peripheral directions away from said middle between the front and rear ends of {TAIL ~ said respective face portion} 
whereby said piston shoes form { HEAD ~ multidirectional hydrodynamic bearing shoes } for forewards and rearwards directed movements of said piston shoes by said curved face portions with said bearing face radii by the extension of said curved face portions equally symmetrical in both peripheral directions away from said middle between the front and rear ends of { TAIL ~ said respective face portion }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL