lost in a 4-bar slider design

[corey796]

i was given a new project yesterday to finish the design of a stopping device for a machine. when a arm retracts it will push a lever and raise another arm.
i believe there is some kind of 4-bar mechanics at work but i just can not see how to use the 4-BAR equations i have found online



i have looked on Google and here the problem is i just don't know what points are what to get it to works.

also i cant attach using the paper clip it is grayed out i can email a dwg

thank you for any help

 

[desertfox]

Hi corey796

I tried uploading a file to indicate your 4 bar linkage within your mechanism but it won't work will try again later.
What equations are you talking about relating to the 4 bar linkage, velocity?

 

[ShaggyPE]

Related to what desertfox is mentioning... what equations are you using. When I have designed four-bars (not frequently btw) there is typically 2 or 3 positions that I am trying to achieve. Using a graphical approach the connections to the fixed frame are determined. Not sure if this helps any.

-Dustin
Professional Engineer
Pretty good with SolidWorks

 

[corey796]

I don't have there papers with me at the moment but I will upload something to night

Thanks for the repleys

 

[corey796]

this shows what i have been working with and what i have done i have 2 fixed points and 3 other points.
i dont know out of the 3 other points what would be the end that slides

 

[desertfox]

Hi corey796

None of the ends you have slide, have a look at this link below
it might help:-

http://www.tep.org.uk/PDF/Mech V1.2 (Master)/4 bar link.pdf

 

[zekeman]

"i was given a new project yesterday to finish the design of a stopping device for a machine. when a arm retracts it will push a lever and raise another arm."

Finish what design? Can you better explain in English what you mean.Or show a sketch of what you have. Copying a Google 4 bar mechanism that has nothing to do with your problem doesn't help, only complicates.

You will never get any meaningful help without a better description.

 

[hydtools]

Constructing your analysis linkage to match your example would be helpful to you. Relate it to your actual problem.

Ted

 

[corey796]

Those are models from solidworks zek why would I add
A sketch as for English 4 other people see the problem and offered helpful advice

 

[zekeman]

Corey,

OK, rereading, so I now think you want a tutorial on 4 bar mechanisms and I take it that you will figure out what configuration of that infinity of arrangements will lead you to a solution. Or do you have something in mind and are looking for analytical closure?

However, I must point out that 4 bar mechanisms have NO sliders so maybe you should consider the slider-crank attached to a 4 bar, for example.

BTW, I didn't mean to offend your thinking or writing but it is very frustrating to get problems where we are trying to help, and the poster does not present a clear picture of what he/she is trying to do. Also, we as problem solvers should do a better job of making sure we understand the inquiry instead of speculating what the poster wants.

 

[Cockroach]

I concur with Zekeman, I see "slider-crank" rather than four bar. Perhaps this is the root to your problem, Corey. This is not a true four bar linkage unless there is other hidden components.

Regards,
Cockroach

 

[desertfox]

corey796

We still don't know what equations your struggling with?

Hi Cockroach I can't see a slider crank mechanism, he has two fixed pivots if you look closely at the diagrams, so I see a four bar linkage albeit that it as limited movement.

 

[btrueblood]

I only see 3 bars, and two fixed pivots...

If Cockroach is confused, I'm not going to try and bend my mind too much further. Corey, can you state what problems you have with the specific model you are showing, i.e. what constraints are you trying to satisfy?

 

[MotionGirl]

Btrueblood. 1 bar is always the frame in a 4-bar.

 

[MotionGirl]

Ok, here is how the mechanism posted by the OP works (with artistic license) - a very simple 4-bar mechanism. Now the only question remaining is ... what does the OP need to do again? To me, the design is all but done in the 3D static CAD view...