wherein said slide faces and {HEAD ~ piston shoes} have a pair of extensions at opposite ends of said medial portions in the direction of {TAIL ~ the movements} of said piston shoes, 
wherein said slide faces and { HEAD ~ piston shoes } have a pair of extensions at opposite ends of said medial portions in the direction of { TAIL ~ the movements } of said piston shoes ,
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH