PURPOSE: To surely fully close sub-throttle valves, by rotatably fitting a cylindrical body to a rotary shaft of the sub-throttle valve, pivotally mounting the cylindrical body to a common lever, further winding a coil spring around the cylindrical body and connecting the cylindrical body to the rotary shaft.

CONSTITUTION: To open and close each sub-throttle valve 23, if a lever 27 is pulled, a disc 42 is rotated, further a cylindrical body 41 is rotated, and rotary motion is transmitted to a rotary shaft 25 through a disc 45, stopped to a spring 43, then the valve is closed. Then even if another sub-throttle valve initially reaches a full closing position, continuous further movement of the lever 27 causes only the disc 42 and cylindrical dody 41 to slidably rotate by an angle θ against the spring 43, and the cylindrical body 41 of each sub-throttle valve slidably rotates for the rotary shaft 25 till the last sub-throttle valve is fully closed, then position shifting of full closing can be absorbed.