According to one embodiment of the invention, the pockets are defined by upstanding walls in the movable element adjacent the surface exposed to {HEAD ~ gases} of {TAIL ~ combustion} 
of
According to one embodiment of the invention , the pockets are defined by upstanding walls in the movable element adjacent the surface exposed to { HEAD ~ gases } of { TAIL ~ combustion }
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 REL TAIL TAIL TAIL TAIL TAIL