An epicyclic gear train was chosen for this B&D screwdriver for several advantages:

1) the system is smaller in volume and can fit into the narrow cylinder case, thereby minimizes the product's overall size

2) the load applied to the gear train is shared among the multiple planets of the system, thereby increasing torque capability

and 3) the shared load and axis provides increased stability of the system.

Multiple calculations were made to analyze the multistage epicyclic gear train (gearbox). These include the gear ratio of each gear set, the overall gear ratio (product of the gear ratios of each set), and the pitch diameters of each gear (planet, sun, ring, and planetary carrier).