Drawing velocity polygon for a press mechanism

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Discussion Overview

The discussion revolves around the task of drawing a velocity polygon for a press mechanism involving gears. Participants are exploring the concepts of velocity vectors and the implications of treating certain points as swivel hinges within the mechanism.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant, @Archives_3, seeks assistance in drawing a velocity polygon and identifies point A as the contact point between two gears, suggesting it may act as a swivel hinge (O2).
  • Another participant points out a lack of clarity regarding the identification of points A and O2 in the provided diagram.
  • After clarification, @Archives_3 reiterates that A is the contact point and assumes it becomes O2 based on the instructions given.
  • A participant expresses confusion about the concept of a swivel hinge and asserts that the larger gear should rotate clockwise, leading to a specific representation of the velocity vector for joint B.
  • This velocity vector for joint B is described as being perpendicular to the radius of the gear and pointing to the right, which then influences the velocity vectors of other joints (C, D, and E).
  • Another participant suggests that the assumptions about the gears need to be confirmed and questions whether the assignment is intended to be a rough representation without numerical values.
  • @Archives_3 acknowledges the need to consult with a professor regarding the assumptions and confirms that the assignment does not require numerical values.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of the swivel hinge concept and the representation of velocity vectors. The discussion remains unresolved regarding the correct approach to drawing the velocity polygon.

Contextual Notes

There are uncertainties regarding the assumptions about the gears and the specific instructions for the assignment, which may affect the interpretation of the velocity polygon.

Archives_3
Messages
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Homework Statement
Draw a velocity polygon and identify absolute and relative velocity
Relevant Equations
Velocity polygon
IMG-20230509-WA0002.jpg
Hello, I'm new to the forum, I want to ask help on this problem here, above is a press mechanism and I'm tasked to draw a velocity polygon based on this mechanism. The point of contact between the two gears is A and consider it as a swivel hinge (rotating but stay still), so I guess it's O2?

Here's my attempt

IMG-20230509-WA0003.jpg

But I feel like it doesn't quite right, if you can help me solve this problem I would be very grateful thank you.
 
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Welcome, @Archives_3 !

Sorry, I don't see points A or O2 in your diagram.
 
Lnewqban said:
Welcome, @Archives_3 !

Sorry, I don't see points A or O2 in your diagram.
My mistake sorry, A is the point of contact between two gears. Now because the instructions that I've not put it in here says that considers A as a swivel hinge, then I assume then A becomes O2.
WhatsApp Image 2023-05-09 at 10.16.35.jpeg

Here's the picture again, I edited the A and B so to not cause confusion anymore I hope.
 
Thank you.
If those discontinuous lines are the meshing circles of two gears with fixed centers, I don't understand the swivel idea.
The bigger gear should have a clockwise rotation.
In that case, the velocity vector of joint B should be represented as perpendicular to the radius of that gear and pointing to the right.
That vector then determines the velocity vectors of joints C, D and E.
 
Lnewqban said:
Thank you.
If those discontinuous lines are the meshing circles of two gears with fixed centers, I don't understand the swivel idea.
The bigger gear should have a clockwise rotation.
In that case, the velocity vector of joint B should be represented as perpendicular to the radius of that gear and pointing to the right.
That vector then determines the velocity vectors of joints C, D and E.
WhatsApp Image 2023-05-09 at 10.57.00.jpeg

So can I see the problem like this?
 
Yes, but only if I am correct about the gears and other assumptions.
Could you consult with your professor?
Is it a number-less assignment, just to represent those vectors in a rough way?
 
Oh okay I understand, I will consult it when I have a chance,
Yes it's a number-less assignment
Thank you for your help
 
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