The pneumatic cylinders 19, 19 and 20 are all connected to the same air supply with {HEAD ~ a special valve} governing {TAIL ~ the flow} of air to the drive element 14 
The pneumatic cylinders 19 , 19 and 20 are all connected to the same air supply with { HEAD ~ a special valve } governing { TAIL ~ the flow } of air to the drive element 14
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH