means responsive to the reciprocable means for generating pulses in {HEAD ~ response} to {TAIL ~ increments} of movement of the reciprocable means 
to
means responsive to the reciprocable means for generating pulses in { HEAD ~ response } to { TAIL ~ increments } of movement of the reciprocable means
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH