Brother International FAX-1010 Service Manual - Page 18

2.3.2 Description of planetary gear system The equipment uses the following three planetary gear systems: - Sun gear 20/90 ("B" in the figure given on the previous page) and its planet gears - Sun gear 36/27 ("N") and its planet gear - Sun gear 39/24 ("R") and its planet gear This section describes the planetary gear system of the sun gear 20/90 ("B"). It consists of the sun gear 20/90, two planet gears 20, arm A, and arm B, as shown below. Planet gear 20B Arm B 0 Sun gear 20/90 ---------. Planet gear 20A Arm A Motor gear Planetary Gear System If the motor rotates, the sun gear 20/90 rotates so that the rotational torque is transmitted to the engagement between the sun gear and the planet gears 20. 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 the sun gear 20/90. If the planet gear(s) becomes engaged with any other gear so that the arm cannot turn furthermore, the rotational torque of the sun gear 20/90 is transmitted to that planet gear. Accordingly, the planet gear starts rotation in the opposite direction of the sun gear 20/90.