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