Page 125 - CITS - Fitter - Trade Theory

FITTER - CITS

2 Pulleys/Sheaves
Pulleys are wheels with grooves around their circumference to hold the belt in place. The driving pulley is connected
to the motor or power source, while the driven pulley is connected to the shaft that receives the power. The size
and speed ratio of the pulleys determine the speed and torque of the driven shaft relative to the driving shaft.
3 Tensioning Mechanism

A tensioning mechanism is used to maintain the proper tension in the belt. This ensures efficient power transfer
and prevents slippage or excessive wear on the belt and pulleys.
4 Bearings

Bearings support the pulleys and allow them to rotate smoothly
Belt drives offer several advantages
- They are relatively simple and economical to design, install, and maintain.
- They can accommodate misalignment between shafts.
- They dampen vibration and reduce noise compared to some other types of power transmission systems.

- They are suitable for applications where the speed ratio needs to be adjusted easily by changing the pulley
sizes.
However, belt drives also have limitations

- They are less efficient than some other types of power transmission systems, such as gear drives or direct
drives.
- Belts can stretch over time, causing a loss of tension and reduced efficiency.

- They may slip under heavy loads or in wet or oily conditions.
- Belts are subject to wear and require periodic inspection and replacement.
Belt drives are commonly used in applications such as automotive engines, industrial machinery, conveyor
systems, and HVAC (heating, ventilation, and air conditioning) systems. They come in various types, including
flat belts, V-belts, timing belts, and ribbed belts, each suited to specific applications based on factors like power
transmission requirements, speed, and environmental conditions.
3 Rope Drives
A rope drive, also known as a cord or wire rope drive, is a type of power transmission system that uses ropes or
cables to transmit mechanical power from one rotating shaft to another. It’s similar in function to belt drives but
uses ropes instead of belts. Rope drives were commonly used in early industrial machinery before the widespread
adoption of belt drives and other transmission systems.
Key components of a rope drive system include
1 Ropes or Cables
The main transmission element of a rope drive system is the rope or cable. These are typically made of
materials like cotton, hemp, or wire, chosen for their strength, flexibility, and resistance to wear.
2 Pulleys/Sheaves
Pulleys or sheaves are used to guide and support the ropes, similar to belt drives. The driving pulley is
connected to the power source, while the driven pulley is connected to the shaft that receives the power. The
size and speed ratio of the pulleys determine the speed and torque of the driven shaft relative to the driving
shaft.
3 Tensioning Mechanism
A tensioning mechanism is used to maintain the proper tension in the ropes. This ensures efficient power
transfer and prevents slippage or excessive wear on the ropes and pulleys.

110

CITS : CG & M - Fitter - Lesson 19