Question

In a reverted gear train gear, A has 16 teeth and drive B having 64 teeth. Gear C having 20 teeth which is compounded with B drives the gear D which is co-axial with A. If the speed of D is 120 rpm what is the speed of A. All the gears have equal module.

• A. 10 rpm
• B. 144 rpm
• C. 1440 rpm
• D. None

Answer 1

The correct option is A 10 rpm


Given:
$z_A=16$
$z_B=64$
$z_C=20$

$m_A=m_B=m_C=m_D$

$\therefore z_A+z_B=z_C+z_D$

$z_D=60$

And, $\frac{N_D}{N_A}=\frac{z_C.z_A}{z_D.z_D}$

$\frac{120}{N_A}=\frac{20\times 16}{60\times 64}$

$N_A=10rpm$