# Drawing velocity polygon for a press mechanism

• Engineering
• Archives_3
In summary, the problem is that the velocity vector of joint B should be represented as perpendicular to the radius of that gear and pointing to the right.
Archives_3
Homework Statement
Draw a velocity polygon and identify absolute and relative velocity
Relevant Equations
Velocity polygon
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

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

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.

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.

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

Lnewqban

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