A front power piston 7 and a rear power piston 8 are connected to the outer periphery of the valve body 6 at {HEAD ~ locations} which are disposed within the front chamber 4 and {TAIL ~ the rear chamber} 5, respectively, and a front diaphragm 11 and a rear diaphragm 12 are applied to the back surfaces of the power pistons 7, 8, respectively 
A front power piston 7 and a rear power piston 8 are connected to the outer periphery of the valve body 6 at { HEAD ~ locations } which are disposed within the front chamber 4 and { TAIL ~ the rear chamber } 5 , respectively , and a front diaphragm 11 and a rear diaphragm 12 are applied to the back surfaces of the power pistons 7 , 8 , respectively
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