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