Question

Which type of idler is used in belt conveyor for transporting granular materials having an angle of repose of not less than 35\(^\circ\)?

• A. Troughing idlers with 35\(^\circ\) trough
• B. Troughing idlers with 45\(^\circ\) trough
• C. Troughing idlers with 20\(^\circ\) trough
• D. Flat belt idlers

Hint:

For grain and moderately cohesive granular materials (angle of repose \(\ge 35^\circ\)), a 35\(^\circ\) trough angle is widely used to maximize capacity without causing excessive belt stress.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Belt conveyors transport bulk solids using idlers to support the belt.
Troughing idlers shape the flat belt into a trough shape to increase cross-sectional carrying capacity and prevent material spillage.

Step 3: Detailed Explanation:
The trough angle of the idler is chosen based on the flowability and angle of repose of the bulk material.
Materials with an angle of repose greater than or equal to 35\(^\circ\) are moderately flowable to non-flowable.
Standard agricultural conveyor designs use 35\(^\circ\) troughing idlers for bulk materials with an angle of repose not less than 35\(^\circ\) to maintain structural stability and prevent material from sliding down the sides of the belt.

Step 4: Final Answer:
Troughing idlers with a 35\(^\circ\) trough angle are selected for this application.