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

• A. 240
• B. - 240
• C. 375
• D. - 375

Answer 1

The correct option is C 375

Given data:

$T_A=20,T_B=30,T_D=20,T_C=80\text{(inner)}$

$T_C=100\text{(Outer)}$

Arm is fixed, no epicyclic nature. Taking a clockwise direction as positive.

$N_A=+300$

$(A,B)N_B=-\frac{300\times 20}{30}=-200$

$(B,C)N_C=-200\times \frac{20}{80}=-75$

$(C,D)N_D=+75\times \frac{100}{20}=+375$