{HEAD ~ A central portion} between {TAIL ~ the housing portions} 40a has a communication hole 12a for vertically movably containing a cam 12 and a stopper groove 40b 
between
{ HEAD ~ A central portion } between { TAIL ~ the housing portions } 40a has a communication hole 12a for vertically movably containing a cam 12 and a stopper groove 40b
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH