The cylinders define {TAIL ~ working chambers} in which a working medium can either be compressed by the pistons or can exert {HEAD ~ pressure} on the pistons 
The cylinders define { TAIL ~ working chambers } in which a working medium can either be compressed by the pistons or can exert { HEAD ~ pressure } on the pistons
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH