Key Parameters for Belt Pulley Selection

When selecting a belt pulley, four key parameters need to be considered:

1. Belt Type (e.g., A, B, C)
   The belt type is chosen based on the torque requirement. In other words, it depends on the amount of power or load that needs to be transmitted. Different belt types offer varying strengths and widths, which are suitable for different load capacities and applications. The selection of the belt type is primarily based on the required torque.
2. Number of Belts
   The number of belts required is also determined by the amount of torque that needs to be transmitted. For higher power applications or heavy loads, multiple belts are often used to improve reliability and reduce the wear on individual belts.
3. Bore Size (Inner Diameter)
   The bore size refers to the diameter of the hole in the pulley that fits onto the shaft. The bore size must match the diameter of the shaft on which the pulley is mounted to ensure a secure fit.
4. Outer Diameter
   The outer diameter of the pulley is chosen based on the desired operational speed. It is calculated in relation to the required output speed, considering the speed ratio between the driving and driven pulleys.

Example: Belt Pulley Selection for a Cutting Machine

Let’s take an example of a cutting machine:

• Motor Power: 2.2 kW, 2-pole motor, rated speed of 2800 rpm.
• Pulley Type: 2A (2A type pulleys are commonly used for medium-power applications).
• Pulley Outer Diameter: 90 mm.
• Transmission Ratio: 1:1 (The driving motor and the cutting machine’s driven pulley operate at the same speed).

In this case, the motor’s rated speed is 2800 rpm, and the cutting machine’s input speed is also 2800 rpm, with a 1:1 transmission ratio. Based on these parameters, the pulley selection would be as follows:

• Belt Type: 2A (suitable for medium power transmission).
• Bore Size: The bore size is chosen based on the motor shaft diameter, which is typically 28 mm in this example.
• Outer Diameter: Based on the required speed and the transmission ratio of 1:1, the outer diameter of both the driven and driving pulleys will be 90 mm.

Thus, the complete pulley model for this application would be: 2A2890.

This model indicates:

• The belt type is 2A;
• The inner bore size is 28 mm;
• The outer diameter is 90 mm.

This pulley setup is suitable for the motor and load combination of the cutting machine, ensuring the proper transmission of torque and speed.