A planetary gear system includes a ring gear supported by a housing, the ring gear having teeth on an inner sidewall of the ring gear, and a plurality of helical gears, each of the plurality of helical gears including a first cylindrical segment having teeth that are configured to mate with teeth of an input drive shaft, the teeth of the first cylindrical segment having helical teeth disposed at a first angle, and a second cylindrical segment extending from the first cylindrical segment, the second cylindrical segment having teeth configured to mate with teeth of the ring gear, the teeth of the second cylindrical segment having helical teeth disposed at a second angle. Advantageously, a linear axial force produced by each of the plurality of helical gears is substantially zero, which creates a thrust balancing within the planetary gear system.