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