A gear train locking device having a locking device is provided. The gear train locking device includes a locking shaft 126 having an outside diameter 128 and a shaft axis. The locking shaft rotates about the shaft axis. Rotation of the locking shaft selectively moves the locking shaft between an engaged position and a disengaged position. The engaged position places the outside diameter of the locking shaft into engagement with at least one gear 110 to provide physical interference between the locking shaft and the gear to change the rotational motion of at least one of the gears. Another embodiment includes a locking shaft that cooperates with a plurality of gears.
