Question
An epicyclic gear train is shown in the figure below. The number of teeth on the gears A, B and D are 20, 30 and 20, respectively. Gear C has 80 teeth on the inner surface and 100 teeth on the outer surface. If the carrier arm AB is fixed and the sun gear A rotates at 300 rpm in the clockwise direction, then the rpm of D in the clockwise direction is
Options :
240
-240
375
-375
Answer :
375
Solution :
T, = 20, TB, = 30, TD = 20, Tc, = 80 (Inner), 7, = 100 (Outer)
Arm is fixed, no epicyclic nature. Taking clockwise direction as positive.
NA = +300
(A, B) NB = -300*20/30 = -200
(B, C) NC = -200*30/80 = -75
(C, D) ND = 75*100/20 = 375
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