This valve assures that the extension shaft 60 of pneumatic cylinder 20 has been completely extended while the extension shafts 35 and 35 of both pneumatic cylinders 19, and 19 on the outside surfaces of cam plates 37 have been completely retracted before drive element 14 begins {HEAD ~ its travel} downward toward {TAIL ~ the frontmost staple} 
This valve assures that the extension shaft 60 of pneumatic cylinder 20 has been completely extended while the extension shafts 35 and 35 of both pneumatic cylinders 19 , and 19 on the outside surfaces of cam plates 37 have been completely retracted before drive element 14 begins { HEAD ~ its travel } downward toward { TAIL ~ the frontmost staple }
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