2.3.2Description of planetary gear system

The equipment uses the following three planetary gear systems:

-Sun gear 24/90 ("B" in the figure given on the previous page) and its planet gears

-Sun gear 65/60 ("K") and its planet gear

-Sun gear 24/28 ("O") and its planet gear

This section describes the planetary gear system of sun gear 24/90 ("B"). It consists of sun gear 24/90, two planet gears 34, arm A, and arm B as shown below.

Planetary Gear System

If the motor rotates, sun gear 24/90 rotates so that the rotational torque is transmitted to the engagement between the sun gear and planet gears 34. Since the arms and planet gears are so designed that the moment of the arms is less than that of the planet gears, the arms turn around the center shaft in the same direction as sun gear 24/90.

If the planet gear(s) becomes engaged with any other gear so that the arm cannot turn furthermore, the rotational torque of sun gear 24/90 is transmitted to that planet gear. Accordingly, the planet gear starts rotation in the opposite direction of sun gear 24/90.

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Brother FAX-931, MFC-970MC, FAX-921 service manual Description of planetary gear system