the extension member is pivotably attached about {HEAD ~ the rotary shaft} between the first position and {TAIL ~ the second position}, 
between
the extension member is pivotably attached about { HEAD ~ the rotary shaft } between the first position and { TAIL ~ the second position } ,
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH