Q-1 In Compound gear trains one must first identify gears that have a moving axis of rotation. These gears are the planet gears. Next, we must identify the links that are connected to the planet by a revolute joint. This link is the arm of the planet considered. Then for each arm found, the planetary gear relation must be written. Consider the gear train given below. Link-1 is the fixed link. Link-3 does not have a fixed axis of rotation. Therefore it is a planet. Link-2 is connected to link-3 by a revolute joint. Therefore link-2 is the arm-a which carries gears A and B on link-3.
Link-3 carries two gears, one with NA = 40-T and the other with NB = 42-T. Link-4 carries two gears, one with NC = 38-T and the other with ND = 12-T. Link-5 carries both a sun gear-E with NE = 36-T and a ring gear-F with NF = 120-T. Link-6 carries gear-G with NG =54-T.