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Pin Pull out force

by yea_right40
Tags: force, pull
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yea_right40
#1
Mar22-10, 06:56 AM
P: 2
Hello,

I need help calculating the (Initial and sustained) Force required to pull a round pin that is under load. I have attached a dim diagram showing the system. Please assume no friction since I haven't selected the materials. Also if you could help me calculate the Sheer force (again, I haven't selected the material) I would really appreciate it. Thanks.
Attached Thumbnails
RELEASE PIN FORCE DIAGRAM.jpg  
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Studiot
#2
Mar22-10, 07:25 AM
P: 5,462
This looks like a schoolwork question.

As it stands you diagram is incomplete. Since you are neglecting friction I suppose this is a shear failure question (note the spelling of shear).

Can you add the appropriate (missing) forces to your diagram?

Also remember that your pull out force is at right angles to the loading so neither has any component in the direction of the other.
yea_right40
#3
Mar22-10, 09:05 AM
P: 2
Hi Studiot,

Thanks for your quick response to my post. See my reply below:

>This looks like a schoolwork question.

Interesting observation. Unfortunaly it is not. This is the release system of a safety latching system I have designed. I haven't had a physics class since 1981 so I am a bit rusty.

>As it stands you diagram is incomplete. Since you are neglecting friction I suppose this is a shear failure question (note the spelling of shear).

Sorry, as I stated in my original post I haven't picked the materials so I can't calculate friction. I am looking for the formula to calculate the initial / sustained force necessary to release the pin (this is so I can select the correct strength solonoid). You are right the second part of my request was to help me with the shear calculation -this will also help me to consider which material I can select. Oh my, you did catch my typo! I won't make that mistake again. Thanks for pointing that out.

>Can you add the appropriate (missing) forces to your diagram?

I am assuming you are looking for friction. I covered that above. If you could assist me in deriving the formula I would appreciate it. If there are other forces that you believe I need please let me know.

>Also remember that your pull out force is at right angles to the loading so neither has any component in the direction of the other.

So friction is the only component to consider?

Thanks.

Studiot
#4
Mar22-10, 10:43 AM
P: 5,462
Pin Pull out force

From what I can see of your drawing, you have a cylindrical bolt being pulled to the left through a journal by a pullout force F that you want to calculate.

You have also shown what looks like a pin set into the bolt on the other side of the journal from F, although this is not shown as such in the section (elevation?) to the right.
Presumably this pin bears against the back of the journal and prevent the bolt withdrawing, so what you need is the force to break (shear) it across.

Without such a pin there is nothing to hold the bolt in place, in the absence of friction.

Can you confirm that I am reading your arrangement correctly?

There is further comment worth making: applying nearly 2 tons of force as shown will certainly tend to rotate the bolt so that it jams in the journal, rather than slides.


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