The piston head is fitted into {HEAD ~ a cylinder} which divides {TAIL ~ the cylinder} into two hydraulic or pneumatic cells 
The piston head is fitted into { HEAD ~ a cylinder } which divides { TAIL ~ the cylinder } into two hydraulic or pneumatic cells
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH