S.S. Hersey View 2

As the hand-driven gear is rotated clockwise a small bevel gear rotates the two larger bevel gears facing each other in opposite directions; however, a modified two-toothed gear on the paring arm is meshed with only one of them. After the paring arm has traveled 180-degrees an incline on the small bevel gear pushes the two-toothed gear across its axle so that it can mesh with the gear traveling in the opposite direction. The result is a parer that automatically switches gears!