At that time {HEAD ~ the other cylinder} 1 and the first flow channel 2 and second flow channel 3 which are connected to {TAIL ~ the other cylinder} 1 are omitted 
are connected to
At that time { HEAD ~ the other cylinder } 1 and the first flow channel 2 and second flow channel 3 which are connected to { TAIL ~ the other cylinder } 1 are omitted
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH