ABE TUTORIALS

AREA 1 PROBLEM 35: PULLEY SPEED AND DIAMETER CALCULATION

A CENTRIFUGAL BLOWER SHALL BE DRIVEN BY A GAS ENGINE. THE SET UP IS AS FOLLOWS: ENGINE SPEED = 2200 RPM; BLOWER SPEED = 1800 RPM; DIAMETER OF ENGINE PULLEY = 25 CM. WHAT SHOULD THE DIAMETER OF THE BLOWER PULLEY BE?

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a. 28 cm

b. 31 cm

c. 61 cm

d. none

Correct Answer: B

Detailed Solution:

In belt-driven systems, the relationship between the speeds (N) and diameters (D) of two pulleys is inversely proportional.

N1 × D1 = N2 × D2

Step 1: Identify the Given Values

• Engine Speed (N1) = 2200 rpm
• Engine Pulley Diameter (D1) = 25 cm
• Blower Speed (N2) = 1800 rpm
• Blower Pulley Diameter (D2) = Unknown

Step 2: Solve for D2

D2 = (N1 × D1) / N2
D2 = (2200 × 25) / 1800
D2 = 55000 / 1800
D2 = 30.55... cm

Result: b. 31 cm (Rounded to the nearest whole number)