Belt Conveyor Pulleys: What are they and its importance

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Introduction

Pulleys serve as essential rotary components within belt conveyors, facilitating movement transfer, directing changes in the belt's path, or stretching the belt as required. These crucial elements consist of four main structural components: the shaft, hub, disc, and cylinder. As illustrated in Figure 1, each of these components plays a fundamental role in the overall functionality of a drum pulley.

Moreover, pulleys are equipped with expansion rings for coupling the shaft to the hub, as well as housings and bearings that enable smooth rotation. Proper selection of the bearing is paramount, as its specifications dictate the choice of housing since each type of bearing necessitates a tailored housing. The selection process hinges on the bearing's fatigue life and support load limits, ensuring reliable performance.

Pulley Types

The operational role of pulleys within a belt conveyor varies based on their positioning, influencing belt direction and contour. Here are several common classifications:

• Return: Positioned opposite the discharge terminal, facilitating the belt's return and potentially acting in tensioning;
• Stretcher (take-up pulley): Maintains optimal belt tension under various operating conditions;
• Drive: Transmits torque and may be located at the discharge, center, or return regions of the conveyor;
• Deviation: Aids in redirecting the belt's trajectory;
• Snub: Increases the belt's embracing angle with the drive drum pulley.

Project and Applications

When designing this equipment, key factors include the width and tensions of the belt, as well as the construction type. Figure 2 illustrates how discs can either be manufactured integrally with the cylinder through welding or constructed by welding to the hub and cylinder separately. Pulley sizing should account for welding types and the associated stress dynamics.

Typically manufactured from steel, the primary function of these pulleys is to drive the belt effectively, hence the criticality of using the drive pulley that connects to the drive unit composed of motors and reducers. For high-belt tension operations, diverse drive configurations, including setups involving multiple pulleys or a dual-drive on a single pulley, may be implemented.

Figure 3 provides an overview of a dual-drive pulley alongside a belt conveyor's braking system.

Given the various applications of pulleys in conveying diverse loads, their design and sizing must correspond to the load capacity specifications of each conveyor. Manufacturing adheres to applicable technical standards to ensure reliability and quality.

The lagging is another crucial aspect when it comes to pulleys, serving to protect them from wear and enhance traction capabilities. When determining the appropriate pulley for your belt conveyor, several factors ought to be evaluated, including equipment cost, installation environment, maintenance convenience, as well as operational parameters such as tension, wrap angle, start-stop cycles, and belt speed. Figure 4 showcases various lagging models tailored for specific applications.

Market Advantages

As market requirements evolve, new opportunities arise for innovation in the design and application of pulleys in environments demanding increased capacity, efficiency, or safety. This ongoing development leads to advanced technologies, with novel lagging options, dimensions, and geometries tailored to specific needs.

A significant benefit of utilizing pulleys is their ability to transport materials over long distances, thereby substantially reducing costs. This reduction is accomplished by minimizing the number of trucks required for material transportation, leading to lower overall operational demands. Furthermore, the reduced direct interaction of employees with the material transport process enhances safety standards. The implementation of belt conveyors also contributes to better control of particulate matter emissions. Various measures that can be incorporated include:

1. Enclosing conveyor belts to mitigate dust dispersion during material transfers;
2. Applying dust suppressants that encapsulate materials, curbing dust emissions;
3. Integrating dedusting systems that filter the air before releasing particles into the atmosphere;

Compatibility between pulleys and conveyors is vital for ensuring seamless integration and avoiding any rework. It is imperative to ensure the pulleys are well-suited to the belts to prevent future modifications or adjustments.

Conclusion

Pulleys face significant cyclic stresses and heavy loads due to belt tensions. The welding processes used in their construction can also lead to weaknesses and crack formation in susceptible areas. Therefore, it is crucial that pulley designs emphasize high reliability through correct manufacturing and adherence to relevant standards, mitigating potential fatigue-related failures and enhancing lifecycle and productivity.

The significance of pulleys in belt conveyor systems is clear, necessitating careful maintenance and management to evade downtime and maintain high operational efficiency and safety levels. Since the drum assembly is comprised of various components, issues with individual elements like bearings or expansion rings can disrupt the entire system's function. Regular inspections and structural evaluations are essential to ensure high reliability of the equipment, enhancing productivity and predictability during maintenance activities.

Kot Engenharia boasts extensive experience in pulley and belt conveyor services, covering finite element analysis, failure diagnostics, along with project improvements. For inspection and structural solution needs, our specialized workforce is ready to support your business. Contact our team today!

References

1. THE FUNCTION AND MECHANISM OF CONVEYOR PULLEY DRUMS - Terry J King Pr. Eng.
2. Manual de Transportadores Contínuos Faço, Ed. Faço.
3. Manual CEMA (Conveying Equipment Manufacturers Association), version 93.
4. Conveying Machines, Spivakovisky and Diaachkov, Editorial Mir.
5. Transporte y Elevacion, P. Alexandrov, Ed. Mir.

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