When the solenoid is excited, the piston is driven for movement to switch {HEAD ~ a flow path} within {TAIL ~ the housing} 
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When the solenoid is excited , the piston is driven for movement to switch { HEAD ~ a flow path } within { TAIL ~ the housing }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL