Jamming a Pulley: Assessing Stress on Shaft & Hole

In summary, jamming the pulley by sticking a broom into one of the holes will result in normal stresses at the hole and torsional stress on the shaft. The magnitudes of these stresses will depend on factors such as the radius of the shaft, distance of the holes from the center of the pulley, and length of the shaft. The biggest torsional stress will be applied to the object with the largest moment of inertia, which is determined by factors such as mass distribution, total mass, geometry, and dimensions. Additionally, the normal stress at the specific hole will be larger when it is closer to the center of the pulley due to the smaller radius at that point.
  • #1
goonking
434
3
A pulley-and-shaft is connected to a motor which applies torque to spin the pulley as shown below:
image392.jpg

Now imagine someone jams machine by sticking a broom into one of the holes of the pulley.
I would imagine there would be normal stresses at the hole (location of jam) and torsional stress on the shaft (from the motor attempting to continue turning), but magnitudes of these stresses would depend on factors like radius of the shaft, distance of holes from the center of the pulley, length of shaft, etc.

Are my assumptions reasonable?
 

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  • #2
In order to jam the pulley, you need to apply a torsional stress on the pulley. In this case, you apply normal stress on the holes (which is torsional on the pulley) and torsional on the shaft, I agree.

I suppose the moment of inertia (of pulley and shaft) is the key in this case. The biggest torsional stress will be applied in the object with the biggest moment of inertia.
The moment of inertia depends on distribution of mass, the total mass, the geometry and the dimensions of the object.

The normal stress that is applied on the specific hole (in which you stick the broom) depends on the distance from the center of the pulley. When you apply this stress near the center, it must be bigger, because radius is smaller there.
 

1. What is the purpose of jamming a pulley?

The purpose of jamming a pulley is to securely attach it to a shaft or hole, preventing it from slipping or rotating independently. This allows for efficient transfer of power and movement between the pulley and the shaft.

2. How do you assess stress on a shaft and hole when jamming a pulley?

To assess stress on a shaft and hole, you will need to consider the magnitude and direction of the forces acting on the pulley, as well as the material properties of the shaft and hole. This can be done through calculations and simulations, or by conducting physical tests.

3. What are the potential consequences of improper pulley jamming?

If a pulley is not properly jammed, it can lead to slipping, misalignment, and potential damage to the pulley, shaft, or surrounding components. This can result in decreased efficiency, increased wear and tear, and even equipment failure.

4. How can you prevent stress on a shaft and hole when jamming a pulley?

To prevent stress on a shaft and hole, it is important to choose a pulley with appropriate dimensions and material properties for the intended application. Additionally, using proper installation techniques, such as ensuring a secure fit and proper lubrication, can help reduce stress and prevent damage.

5. Are there any best practices for jamming a pulley?

Yes, there are several best practices to keep in mind when jamming a pulley. These include selecting a pulley with the correct size and material, ensuring a secure fit, avoiding overloading the pulley, and regularly inspecting and maintaining the pulley and surrounding components. It is also important to follow manufacturer instructions and guidelines for proper installation and use.

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