{TAIL ~ A force} modifying {HEAD ~ member rotatable} about a fixed axis is provided and includes first and second outwardly facing surfaces of predetermined lengths which curve about the axis 
{ TAIL ~ A force } modifying { HEAD ~ member rotatable } about a fixed axis is provided and includes first and second outwardly facing surfaces of predetermined lengths which curve about the axis
TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH