{TAIL ~ The current} is automatically reversed at the point of {HEAD ~ zero motion} of the reciprocating mechanism during each rebound 
{ TAIL ~ The current } is automatically reversed at the point of { HEAD ~ zero motion } of the reciprocating mechanism during each rebound
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH