A planetary gear reduction system 5, wherein {HEAD ~ said casing} includes a first member and a second member abutting opposing ones of said axial ends of {TAIL ~ said internal gear} 
A planetary gear reduction system 5 , wherein { HEAD ~ said casing } includes a first member and a second member abutting opposing ones of said axial ends of { TAIL ~ said internal gear }
OTH OTH OTH 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 TAIL