- #1
Vertical alignment mechanism on eccentric shaft
Click For Summary
Discussion Overview
The discussion revolves around designing a mechanism to maintain horizontal alignment of a table while an eccentric circle rotates around a larger center circle. The focus includes theoretical and practical aspects of mechanical design, particularly in relation to motion transfer and stability in a vibrating platform application.
Discussion Character
- Technical explanation
- Conceptual clarification
- Debate/contested
Main Points Raised
- One participant inquires about the appropriate mechanism to keep a table horizontal while an eccentric circle rotates.
- Another suggests looking at historical steam engine designs for inspiration on converting linear motion to rotational motion.
- A participant mentions the "scotch yoke" as a potential mechanism to explore.
- Questions arise regarding the necessity of a rectangular prism for the piston’s motion and the implications of removing it.
- Clarifications are requested about the components involved, specifically the "bottom half of the yolk" and its function.
- A participant describes their design involving a flywheel and a smaller shaft with a specified offset, detailing the intended motion of the platform.
- There is a discussion about the role of the yoke in maintaining horizontal alignment and the potential for alternative methods to achieve this stability.
- Suggestions are made to use a rectangular plate with a horizontal slot and vertical rails to guide the mechanism, with an emphasis on precision and the use of ball bearings.
Areas of Agreement / Disagreement
Participants express differing views on the necessity and design of the yoke and other components, indicating that multiple competing approaches exist without a clear consensus on the best solution.
Contextual Notes
Participants mention various mechanical components and their functions, but the discussion lacks clarity on specific design parameters and assumptions regarding the motion and forces involved.
- #2
BvU
Science Advisor
Homework Helper
- 16,219
- 4,934
You could check out some old drawings of how steam engines convert the to-and-fro of the cylinder to a rotating shaft with a flywheel...
(Or how modern combustion engines do the same
)
(Or how modern combustion engines do the same
)- #3
JBA
Science Advisor
Gold Member
- 1,532
- 462
Also do a web search on "scotch yoke"
- #4
wakadarc
- 34
- 0
- #5
JBA
Science Advisor
Gold Member
- 1,532
- 462
I need for to be a bit clearer about your question or what alternative assembly you are thinking about.
If you rotate the assembly vertical with the table on the end of the rod and depend upon the table weight to return the pin to the bottom of the stroke then the bottom half of the yolk could be eliminated.
If you rotate the assembly vertical with the table on the end of the rod and depend upon the table weight to return the pin to the bottom of the stroke then the bottom half of the yolk could be eliminated.
- #6
wakadarc
- 34
- 0
Whats the bottom half of the yolk? Whats the yolk?
Yes the flat table will rest on the end of that piston. My flywheel will be the driver, it will be rotating and that smaller white shaft will rotate about it (1/4" offset.) I am designing a vibrating platform that will move up 0.5" and down 0.5". The weight will be 150kg (table + box load)
Thanks for your response
Yes the flat table will rest on the end of that piston. My flywheel will be the driver, it will be rotating and that smaller white shaft will rotate about it (1/4" offset.) I am designing a vibrating platform that will move up 0.5" and down 0.5". The weight will be 150kg (table + box load)
Thanks for your response
- #7
JBA
Science Advisor
Gold Member
- 1,532
- 462
What you call the rectangular prism in which the pin slides back and forth is generally known as the yoke.
- #8
wakadarc
- 34
- 0
Right, so a slider(the yolk) will be necessary to keep the platform horizontal because without it, the piston can tilt.
Is there any other method to keep the slot the eccentric cam rides into stay horizontal?
Is there any other method to keep the slot the eccentric cam rides into stay horizontal?
- #9
JBA
Science Advisor
Gold Member
- 1,532
- 462
If you mean other than the vertical shaft, then making the yoke a rectangular plate with a horizontal slot for the pin and adding vertical rails to guide the side edges of the plate has also been used. Preferably, rollers that ride inside of slots in the guide rails are added to the top and bottom corners of the plate.
- #10
JBA
Science Advisor
Gold Member
- 1,532
- 462
wakadarc,
I am going to be offline for a while; but I will check back in somewhat later today to see if you have any more questions.
I am going to be offline for a while; but I will check back in somewhat later today to see if you have any more questions.
- #11
wakadarc
- 34
- 0
No problem.
With the animation I posted, ideally I would like to keep that exact motion without having the rectangular prism (yolk). Guide rails requires precision and what not. Yes for the slot the eccentric shaft will ride in, there I will be using ball bearings.
Thanks JBA
With the animation I posted, ideally I would like to keep that exact motion without having the rectangular prism (yolk). Guide rails requires precision and what not. Yes for the slot the eccentric shaft will ride in, there I will be using ball bearings.
Thanks JBA
Similar threads
- · Replies 18 ·
- · Replies 1 ·
- · Replies 4 ·
- · Replies 5 ·
- · Replies 4 ·
- · Replies 1 ·