help with pin slot joint

[eamartin52]

I am working on a steam engine model, and need some help with the eccentric and valve mechanism.

The eccentric is rigid jointed to a crankshaft (yellow). The eccentric strap (blue) is joined to the eccentric with revolute joint. The linkage (in green), is connected to the brackets (black) via revolute joint. I then applied a pin slot joint between the horizontal lever, (it has a ball on the end), and socket (red). The eccentric rotates and moves up and down like it should, but the revolute on the green linkage doesn't work. I f I suppress tie pin slot joint, the eccentric doesn't work, but the linkage revolves properly. The question is how do I cause the eccentric move up and down, and engage the linkage causing rocking back and forth?

[jhackney1972]

You need to attach your model.  Open it in Fusion 360, select the File menu, then Export to your hard drive.  Attach the F3D or F3Z file to the Attachments section on your next post.

[davebYYPCU]

Yep that will bind as you have it.

Green arm moves away in an arc from the fixed plane the blue rod lives on.

I suggest you use the joints as depicted,

Red has PinSlot for the blue pin, and the swivel on green arm, that rotates on an axle through the black.

Might help....

[eamartin52]

Thank you John for the reply. I didn't know you were on here.

BTW I have watched all your videos, and have enjoyed them immensely. I especially liked the rolling wheel video.

Anyway, here is a pared down version of the file in question. This is actually the last part to this project.

[eamartin52]

I'm going to try that. Your solution makes sense due to the sliding action of the lever moving away from the eccentric.

[jhackney1972 · Accepted solution]

I think the motion between the eccentric strap and the body 1 component is too complex for a Pin-Slot joint.  It would seemed to me that a Ball Joint would be a better choice so I tried it. Unfortunately this joint also will not allow for motion in Fusion 360.  I am adding my model with these modifications to show my idea and changes.  I will continue to think about it.

 

[jhackney1972 · Accepted solution]

Since I believe that there are two many motions for a simple Pin-Slot Joint and the Ball Joint would not work, I added an Intermediate Component.  This component is jointed to the Body 1 component with a Revolve joint and is joined to the Eccentric Strap with a Cylindrical Joint.  This gives the three motions, plus the connection, needed to drive this mechanism.  The component is then hidden in the assembly.  You Body 1 component may need to be a bit longer to keep it in the housing.  My solution is attached.

[eamartin52 · Accepted solution]

wow, that's awesome. You use a dummy component, just like your rolling wheel.

That's thinking outside the box.

[eamartin52 · Accepted solution]

wow, that's awesome. You use a dummy component, just like your rolling wheel.

That's thinking outside the box.

Thanks

Eric Martin