line duct 101 q that is connected to the inlet 101 j and then turns back at a sharp angle to enter into the arc shaped flow path ls 1 to rise at a perpendicular at the end of this arc shaped flow path ls 1 referencing fig9 to be sent to the pilot relay 4 as air of the supply air pressure ps 1 in this case the air flows along the arc shaped flow path ls 1 that is the air flows along a smooth flow path with little curvature so there is little variation in cross sectional area reducing the flow path resistance in the present invention in the part of the flow path ls 1 wherein it bends back at a sharp angle that is at the part wherein the straight line duct 101 q and the flow path ls 1 are joined an air reservoir 101 r with a depth of 30 mm is provided this air reservoir 101 r serves as a resonator making it possible to reduce the flow path resistance through the effects of this chamber furthermore the air of the supply air pressure ps from the inlet 101 j rises at a perpendicular from this air reservoir resonator 101 r to be sent to the pilot relay 4 as air.