BOGIE AXLE DEVICE BALANCE SYSTEM AND BOGIE AXLE DEVICE

[Problems] To provide a bogie axle device and a balance system which are capable of obtaining a high balance ratio at a low cost. [Problems] To provide an exhaled-air pressure measuring device capable of deciding on exhaled-air pressure levels suitable for usage purposes. [Means for solving the Problems] A balance system 4L includes: a reaction-force separating mechanism 41L in which a driving force is inputted from a driving unit; and a planetary gear mechanism 42L which transmits, to a swing housing, a reaction force for suppressing a swing of the swing housing. The reaction-force separating mechanism 41L separates the inputted driving force, without employing any ring gear, into a driving force to be inputted in a driving-force transmitting mechanism and a reaction force to be inputted in the swing housing. The planetary gear mechanism 42L amplifies the reaction force, inputs it in the swing housing and generates a swing suppressing torque for suppressing a swing of the swing housing.