Preferably, {TAIL ~ the compressor} includes a delivery control mechanism responsive to pressure in the suction passageway to vary the effective cross sectional area of {HEAD ~ the suction passageway} 
Preferably , { TAIL ~ the compressor } includes a delivery control mechanism responsive to pressure in the suction passageway to vary the effective cross sectional area of { HEAD ~ the suction passageway }
OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL 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