Pulley Diameter knowing only force and motor specifications

In summary: But you have the force on the lever arm of one of the pulleys, and you have the ratio of their diameters.
  • #1
mr_xyz
2
0
TL;DR Summary
Determine the size of pulleys in a belt drive system where only known factors force in the bigger pulley and motor specifications used to drive the smaller pulley.
Hello,

How to determine the pulley diameters? The only know factors are listed below.
The smaller pulley is attached to a motor that drives the belt drive system. The bigger pulley is driven and has a lifting force of 45N.

Known factors:
How to determine either the smaller or bigger pulley diameter?
 

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  • #2
mr_xyz said:
Summary: Determine the size of pulleys in a belt drive system where only known factors force in the bigger pulley and motor specifications used to drive the smaller pulley.

Hello,

How to determine the pulley diameters? The only know factors are listed below.
The smaller pulley is attached to a motor that drives the belt drive system. The bigger pulley is driven and has a lifting force of 45N.

Known factors:
How to determine either the smaller or bigger pulley diameter?
Welcome to the PF. :smile:

Are you familiar with how to calculate torque, given the force and the length of the lever arm? Could you show us your initial torque calculations for this problem? Thanks.
 
  • #3
berkeman said:
Welcome to the PF. :smile:

Are you familiar with how to calculate torque, given the force and the length of the lever arm? Could you show us your initial torque calculations for this problem? Thanks.

Hi, thank you for your reply :smile:

Yes I am, I know that τ = F * a
My problem is that I don't have the radius of the bigger pulley, which I assume would be the lever arm. So I'm a bit stuck with finding the torque for the big pulley.
 
  • #4
mr_xyz said:
Yes I am, I know that τ = F * a
My problem is that I don't have the radius of the bigger pulley, which I assume would be the lever arm. So I'm a bit stuck with finding the torque for the big pulley.
But you have the force on the lever arm of one of the pulleys, and you have the ratio of their diameters. Other than MOI issues, the absolute size of the pulleys would seem to matter less than the ratio for this problem, no?
 

1. What is the relationship between pulley diameter and force?

The pulley diameter and force have an inverse relationship. This means that as the pulley diameter increases, the force required to move the load decreases. Similarly, as the pulley diameter decreases, the force required to move the load increases.

2. How do motor specifications affect the choice of pulley diameter?

The motor specifications, such as its torque and speed, play a crucial role in determining the appropriate pulley diameter. The pulley diameter should be chosen in such a way that it matches the motor's torque and speed capabilities to ensure efficient and smooth operation.

3. Can the force and motor specifications be used to calculate the ideal pulley diameter?

Yes, the force and motor specifications can be used to calculate the ideal pulley diameter using the formula: pulley diameter = (force * distance) / (motor torque * 2 * pi). This formula takes into account the force required to move the load and the motor's torque and speed.

4. What happens if the pulley diameter is too small or too large?

If the pulley diameter is too small, it will require a higher force to move the load, which can put strain on the motor and decrease its efficiency. On the other hand, if the pulley diameter is too large, the load may not move at all as the force provided by the motor may not be enough to overcome the load's weight.

5. Are there any other factors to consider when choosing the pulley diameter?

Yes, in addition to the force and motor specifications, other factors such as the type of load, the speed and direction of rotation, and the space constraints should also be considered when choosing the pulley diameter. It is important to select a pulley diameter that can effectively handle the load and operate efficiently in the given space and conditions.

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