What is the important dimension in this brain teasing system?

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Discussion Overview

The discussion revolves around optimizing a hydraulic mechanism designed to maximize vertical lift at a specific point while minimizing the force required. Participants explore various aspects of the system, including pivot points, linkages, and moment arms, while debating the best approach to achieve the desired mechanical advantage.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant seeks advice on which components of the hydraulic mechanism (linkages, pivot points, moment arms) should be adjusted to maximize lift at point C with minimal force at F.
  • Another participant questions the choice of hydraulics over a block and tackle or compound pulley system, asking for clarification on the intended application.
  • A participant discusses the mechanics of levers, suggesting that increasing force at the load end results in decreased displacement, and emphasizes the importance of understanding the relationship between the angles and movements of the components.
  • Concerns are raised about the attachment points of the mass M and link CD, with a suggestion that a different attachment point may yield better results.
  • A participant expresses a specific interest in maximizing the length of Moment Arm 3 and achieving a near 90-degree angle at BDF to enhance lift at the initial movement of the system.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the optimal configuration or approach for the hydraulic mechanism, with multiple competing views and suggestions remaining unresolved.

Contextual Notes

There are uncertainties regarding the definitions of terms used (e.g., moment arm) and the specific mechanics of the proposed system, which may affect the discussion's conclusions.

Who May Find This Useful

Individuals interested in mechanical engineering, hydraulic systems, or those working on similar design challenges may find this discussion relevant.

rsmutt1978
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Though it may seem like it, this certainly isn't a homework question so I hope I don't offend anyone with it's placement. This is a simple drawing of a hydraulic mechanism that me and a friend are building. There is much debate about where we need to improve so we are leaving it up to you, the 'professionals' to settle the argument.

I included all the details in the attached drawing. Let me know what you guys think.

View attachment PHYSICS POST, simple.pdf
For clarification, points A, B, C and D are all PIVOT POINTS!
 
Last edited:
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Upon what do you and your friend disagree?
 
Which items (linkages BD or CD, pivot points B, D, C or A, Moment Arm 1, 2 or 3) need to be adjusted to create the most lift possible at point C with the least amount of force at F? Perhaps the simple/general question is, 'What can we do in this system to maximize vertical lift at C with minimal F and without changing the angle of vector DF.
 
Its still confusing to me. Why not just use a block and tackle/compound pulley? Why are you using hydraulics and what is it for?
 
Because once it is folded in it must push out as well. The movement out is not an issue though. Attached is the detailed drawing of the system. Luckily my day job is in SolidWorks. HA HA.
 

Attachments

You might want to review how a lever works as a force or displacement multiplier. If you want more force at the load end you sacrifice displacement, and vice verse ( more displacement at the load end means less force at the load end ).

A simple lever, or a modified L shaped lever ( to change direction of the force and displacement ) have shear in the members. The way your linkages are set up it appears the members 1,2,3 will be in tension or compression, with minimized shear.

What you will have to do is
as BD rotates around fulcrum B, point D moves along an arc of a circle. Member DC comes along for the ride lifting your load M. If CA was not there ( ie CD would hang vertical ) then the displacement of load M would be merely a simple angle function of movement of BD. Since CA does control some of the movement of load M, at least horizontal and vertical you will need to find the more complicated equation that relates the angle of movement of BD to that of the load M using basic trigonometry.

That is the way I see the solution to your problem.
and you can lengthen or shorten the members and see what that gives you as a result to maxmize displacement, if that is what you are after when you say lift.
 
Your first diagram shows mass M and link CD attached to the same point on link AC. However having looked at your second diagram I suspect it would be better to show mass M attached to a different point.
 
256 & CWatters

I appreciate both of your input. It would probably help if I told you that the mass M is really a frame member that extends out horizontally. Once it starts to lift/rotate up around hinge A it will immediately be moving easier and easier. Because of this, I am only concerned with maximizing "lift" at the moment that it is just starting to move.

It seams to me that getting Moment Arm 3 (sorry if my terms are inaccurate) as long as possible would give me the most lift possible. Also, getting angle BDF to be as close to 90 as possible.
 

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