Crank Mechanism

[memoi567]

Hi,

Do these equations work if my crank mechanism is offset? As far as I can tell the displacement equation will stay the same, but I'm not sure about the rest.

https://www.engineersedge.com/mechanics_machines/piston_slider_crank_mechanism_14925.htm

Regards

 

[rb1957]

offset ? … out-of-plane ?? then there'll be some additional loads

another day in paradise, or is paradise one day closer ?

 

[rb1957]

since you've got a bunch of different parameters (compared with the first link) …
what does "the displacement equation will stay the same" mean ?

the block will translate long the surface, but different to the "inline" crank,
the forces are "all" different ...

another day in paradise, or is paradise one day closer ?

 

[memoi567]

My picture was deleted for some reason, but that picture was just an image I took off google the parameters in it were not the ones I was using. I was just using that image as an example since you didn't know what an offset crank mechanism is. However, you are correct in that there is an additional parameter which is the offset distance between the origin and the slider.

As for what I meant by "the displacement equation will stay the same":

In an offset model the displacement can be calculated the same way. The cos(theta of link 1) + the cos(fi of link 2) still equals to the displacement of the slider. Adding a vertical parameter will not change the horizontal parameter.

I am not calculating forces, but your last comment makes me think if the forces are different than the accelerations are different. Thus, I can conclude that I should derive new equations for my model(the offset crank mechanism)

 

[cowski]

The horizontal linear stroke will reduce as the vertical offset increases.

 

[rb1957]

is this school work ? (that's why posts were deleted)

posting "random" pictures off the internet does not convey your problem, or your understanding of it, clearly.

your expression "cos(theta of link 1) + the cos(fi of link 2) still equals to the displacement of the slider" is probably correct,
but "Adding a vertical parameter will not change the horizontal parameter" isn't. The reason is that phi and theta have a different relationship with the offset.

Adding the offset change the motion of the slider.

another day in paradise, or is paradise one day closer ?

 

[memoi567]

"The reason is that phi and theta have a different relationship with the offset"

This is what I suspected, and wanted to confirm. Thanks, for your help.

As for the "random" picture I disagree. I thought it conveyed the two different models very well and if you don't think it conveyed my understanding at the very least it conveyed my misunderstanding which is also valuable.

Regardless, Thanks for the help