One of the further chambers contains a first electro magnetic control valve fed by a D.C. voltage, and operable to control an orifice through which {HEAD ~ the first chamber} communicates with {TAIL ~ atmosphere} 
communicates with
One of the further chambers contains a first electro magnetic control valve fed by a D.C. voltage , and operable to control an orifice through which { HEAD ~ the first chamber } communicates with { TAIL ~ atmosphere }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL