direction of arrow 66 the flanged surface 74 of the output shaft 50 displaces fluid from gap 72 through the channels 76 into the gap 70 of the input bore 49 the input shafts 48 are forced in a direction of arrow 68 taken together the fluidomechanical coupler 16 is configured to translate an input force into an output response in a direction opposite the input force with the advantageous structure of function of the fluidomechanical coupler 16 developed reference is made to fig6 fig6 illustrates the so called drivetrain 77 of the fuel injector 10 the drivetrain 77 can include the magnetostrictive actuator 28 with or without end caps 42 input shafts 48 output shaft 50 needle stop 56 quill 52 biasing element 78 and needle element 54 the drivetrain 77 is disposed within the various housings of the fuel injector 10 as disclosed herein and as partially illustrated in fig1 and 2 referring to fig1 and 2 the quill 52 biasing element 78 and needle element 74 are not shown but it can be appreciated that the quill 52 is positioned adjacent to the output shaft 50 the quill 52 biasing element 78 and needle element 54 are disposed within the injector housing 18 a nozzle 80 is associated with the fuel injector 10 at the nozzle end 24 the needle element 54 is positioned proximate to the nozzle end 24 and moveable between a closed position and an open position in the closed position the needle element 54 obstructs the nozzle 80 such that.