# The chain drive is used to reduce the speed from 180 rpm to 90 rpm, the driving sprocket has 20 teeth and pitch circle diameter of 500 mm. The centre to centre distance between the sprockets of chain drive is 550 mm. Determine total number of links.

The chain drive is used to reduce the speed from 180 rpm to 90 rpm, the driving sprocket has 20 teeth and pitch circle diameter of 500 mm. The centre to centre distance between the sprockets of chain drive is 550 mm. Determine total number of links.

(a) 65

(b) 100

(c) 45

(d) 115

The question was asked in an internship interview.

My query is from Mechanical Power Transmission in division Mechanical Power Transmission of Farm Machinery

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Correct option is (c) 45

The explanation is: $\frac{N1}{N2} = \frac{T2}{T1}$

T2=$\frac{180*20}{90}$ = 40 teeth

Pitch = $\frac{πD}{T} = \frac{π*0.5}{20}$ = 0.078m

L = 2*0.55+$\frac{0.078}{2}$(20+40)+$\frac{[(0.078)^2 (20-40)^2]}{4*π^2*0.55}$

L = 3.55 m

Number of links Ln = $\frac{L}{P}=\frac{3.55}{0.078}$ = 45.

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