The first state of the pump corresponds to {HEAD ~ a first rotational direction} of {TAIL ~ the pump}, and the second state of the pump corresponds to a second rotational direction of the pump 
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The first state of the pump corresponds to { HEAD ~ a first rotational direction } of { TAIL ~ the pump } , and the second state of the pump corresponds to a second rotational direction of the pump
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH