# Design of Heavy-Duty Pulleys for Belt Conveyors
## 1. Introduction
Heavy-duty pulleys are critical components in belt conveyor systems, ensuring efficient power transmission, belt tracking, and load support. Proper design ensures durability, reliability, and minimal maintenance.
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## 2. Key Design Considerations
(A) Load & Duty Requirements
– Belt Tension (kN/m) – Determines pulley shaft and shell strength.
– Conveyor Speed (m/s) – Affects pulley diameter selection.
– Material Bulk Density (kg/m³) – Influences pulley load capacity.
– Environmental Conditions – Corrosion, abrasion, or high temperatures require special materials/coatings.
(B) Pulley Types
1. Drive Pulley – Transmits power from motor to belt.
2. Bend Pulley – Changes belt direction.
3. Snub Pulley – Increases wrap angle on drive pulley.
4. Take-Up Pulley – Adjusts belt tension.
5. Tail & Head Pulleys – Located at conveyor ends.
(C) Materials & Construction
– Shell: Typically made from steel (carbon steel, stainless steel).
– Lagging: Rubber or ceramic coating to improve traction and reduce wear.
– Shaft: High-strength alloy steel with proper fatigue resistance.
– End Discs & Hubs: Reinforced for load distribution.
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## 3. Design Calculations
(A) Pulley Diameter Selection
\[
D = \frac{C \cdot T_{\text{max}}}{\sigma_b}
\]
Where:
– \( D \) = Minimum pulley diameter (mm)
– \( C \) = Empirical factor (based on belt type)
– \( T_{\text{max}} \) = Maximum b tension (N/mm)
– \( \sigma_b \) = Allowable bending stress of the belt
(B) Shaft Design
\[
d = \left( \frac{16 \cdot T}{\pi \cdot \tau} \right)^{1/3}
\]
Where:
– \( d \) = Shaft diameter (mm)
– \( T \) = Torque (N·mm)
– \( \tau \) = Allowable shear stress (MPa)
(C) Bearing Selection
Based on radial and axial loads:
\[
L_{10} = \left( \frac{C}{P} \right)^3
\