In {HEAD ~ an alternative example}, {TAIL ~ the drivetrain assembly} remains stationary but a collar 74 surrounding the bit is made to translate axially and actuate a switch 
In { HEAD ~ an alternative example } , { TAIL ~ the drivetrain assembly } remains stationary but a collar 74 surrounding the bit is made to translate axially and actuate a switch
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH 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