An epicyclic gear train consists of sun wheel S, a fixed internal gear E and three identical planet wheels P carried on a star-shaped planet carrier C, as shown in Fig. 15.20. The planets rotate at 1/5th of the speed of sun wheel. The minimum number of teeth on any wheel is 18. The driving torque on the sun wheel is 120 Nm. Find (a) number of teeth on different wheels of the train and (b) torque neces- sary to keep the internal gear stationary. E S Fig.15.20 Epicyclic gear train