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