In the provided diagram, the pinion gear is positioned to the left of the aperture in the starter motor where it engages with the ring gear. The functionality of the peculiar gap in the armature shaft remains unclear. It is presumed that the pinion gear must shift towards the right in order to engage with the motor's ring gear. However, if that is the case, how does the pinion gear mesh with the armature and occupy the gap in the shaft situated just below the ground symbol?