Question

The required speed of stirrer of process vessel is 60 R.P.M. The RPM of electric motor is 1450. The reduction of speed is in two stages, i.e., first by V belt pulley drive and then by reduction gear of ratio 15 : 1. The diameter of pulley maintained on motor shaft is 200mm. What will be the diameter of pulley mounted on gear box shaft?

Instrumentation question! answer only if you know!​

Answer 1

$\fbox{\texttt{\green{Answer:}}}$

Diameter of pulley mounted on gear shaft = 322.2 mm

$\fbox{\texttt{\pink{Given:}}}$

• R.P.M of wheel D = 60 R.P.M
• R.P.M of electric motor = 1450
• D and C are gear wheels of teeth ratio = 15 : 1
• Diameter of pulley on motor shaft(A) = 200 mm

$\fbox{\texttt{\orange{To\:find:}}}$

Diameter of pulley mounted on gear box shaft(B).

$\fbox{\texttt{\red{How\:to\:Find:}}}$

B is the pulley mounted on gear box shaft and we have to find out diameter of B as required in the problem(refer to the attached image).

We know, R.P.M. of D = 60 R.P.M.

R.P.M. of C = 15 × 60 = 900 R.P.M.

∵ Smaller pulley revolves many times than the larger pulley. We can guess this by inspection itself.

$\hrulefill$

Now, R.P.M. of C and R.P.M. of B is same.

∵ They both are mounted on the same shaft.

∴ R.P.M. of B = 900 R.P.M.

It is given 200 mm diameter pulley revolves at 1450 R.P.M.

∴ 1450 R.P.M. wheel diameter = 200 mm

∴ 900 R.P.M. wheel diameter =

$\bold{\dfrac{1450}{900}\times{}200=\dfrac{2900}{9}=322.2\:mm}$

∴ Diameter of pulley mounted on gear shaft(B) = 322.2 mm.

(nice question)