抄録
Characteristics of pitching machines using more than three rotating wheels are analyzed by vector analysis. The vector expressions give straightforward the necessary wheel velocities and offset angles of the wheel shafts, being coplanar each other, for an arbitrary ball velocity and its spin velocity. To obtain the ball velocity and offset angle of the wheel shafts the vector analysis is simpler than a schematic method. A three wheels pitching machine without offset angles of the shafts only throw balls with spin axis perpendicular to the thrown direction. The offset angles of the shafts and the wheel velocities of arbitrary selected two wheels define the offset angles and the wheel velocity of other wheels.
