Understanding V-Belt Tension and Forces: Exploring a FBD Diagram

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In summary, the conversation discusses a diagram showing belt tension and the confusion surrounding the representation of forces. The diagram is incomplete and could benefit from clearer labeling and differentiation of forces. The conversation also mentions a resource with a more accurate diagram for reference.
  • #1
etotheipi
I found this diagram,

1590221457366.png


How does the belt tension arise? I would assume it be exerted by belt elements on either side (i.e. unbalanced tension forces due to curvature around the pulley), but that's not clear from this diagram.

Also, just to make sure I'm not going crazy, why have they drawn two forces of ##\frac{1}{2}\mathbf{F}_1## on here? I'm pretty sure they're intended to be vector components of the force ##\mathbf{F}_2## on the walls due to the belt, but if so then it's not really that clear :confused:. Thank you!
 
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  • #2
Hi,
A sideways view would reveal tension along the heart line of the belt, as you expect. Most of it is pulling the belt into the groove.
You're not going crazy (at least not in this matter :smile: ). The two ##{1\over 2}{\bf F}_1## is what the belt exerts on the pulley.
In that respect this is an (incomplete) FBD of the pulley, not of the belt.
 
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  • #3
BvU said:
The two ##{1\over 2}{\bf F}_1## is what the belt exerts on the pulley.
In that respect this is an (incomplete) FBD of the pulley, not of the belt.

Ah okay awesome. `I just wondered since I think it would be clearer to draw the two ##\frac{1}{2}\mathbf{F}_1##'s with dotted lines instead of solid lines, since that diagram is double counting the vertical component of the reaction force.

Thank you!
 
  • #4
There will be a context for this diagram. That may say "this diagram shows how the belt tension is propagated to the pulley", as opposed to the incorrect "this is an FBD of the belt" -- because then reversing the two ##{1\over2}1{\bf F}_1## and ##{\bf F}_2## would be better, but then the diagram becomes cluttered and unclear.
 
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  • #5
BvU said:
There will be a context for this diagram. It's not 100% corerct for sure. Reversing the two ##\frac{1}{2}\mathbf{F}_1## and ##\mathbf{F}_2## would be better, but then the diagram becomes cluttered and unclear.

I would get rid of the ##\frac{1}{2}\mathbf{F}_1## arrows entirely.
 
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  • #6
@BvU I would draw a diagram like this, where the 3 inner forces act on the V belt and the two outer ones act on the groove/pulley:

1590231670715.png

Whilst we could also add components in, I would make sure to distinguish them clearly:

1590231814746.png


My opposition to the presence of the two ##\frac{1}{2}\mathbf{F}_1## arrows is because one might then be inclined to believe erroneously that it is a separate force acting on the V belt, as opposed to a vertical component of an existing force on the diagram.
 
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FAQ: Understanding V-Belt Tension and Forces: Exploring a FBD Diagram

What is a FBD diagram?

A FBD (free body diagram) is a visual representation used in physics and engineering to analyze the forces acting on an object. It consists of a simplified drawing of the object with all external forces acting on it, such as gravity, tension, and friction, shown as arrows.

How is a FBD diagram used to understand V-belt tension and forces?

A FBD diagram can be used to analyze the forces acting on a V-belt system, such as the tension forces exerted by the belt and pulleys. By drawing the forces on the diagram, we can determine the net force and direction of motion of the belt, as well as calculate the tension forces needed for the belt to function properly.

What factors affect V-belt tension?

The tension in a V-belt is affected by several factors, including the size and speed of the pulleys, the angle of the V-belt, and the material and condition of the belt itself. The tension must be carefully calculated to ensure proper functioning of the belt and prevent slipping or excessive wear.

What is the relationship between tension and force in a V-belt system?

In a V-belt system, the tension force is what keeps the belt in contact with the pulleys and allows it to transmit power. The tension force is directly related to the amount of force or torque that can be transmitted by the belt. As the tension increases, so does the force that can be transmitted.

How can understanding V-belt tension and forces benefit engineers and designers?

By understanding V-belt tension and forces, engineers and designers can ensure that their belt systems are properly designed and maintained for optimal performance. This can lead to increased efficiency, reduced wear and tear on equipment, and improved safety in industrial settings.

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