Mechanism Definition and 534 Threads

In engineering, a mechanism is a device that transforms input forces and movement into a desired set of output forces and movement. Mechanisms generally consist of moving components which may include:

Gears and gear trains;
Belts and chain drives;
Cams and followers;
Linkages;
Friction devices, such as brakes or clutches;
Structural components such as a frame, fasteners, bearings, springs, or lubricants;
Various machine elements, such as splines, pins, or keys.The German scientist Franz Reuleaux defines machine as "a combination of resistant bodies so arranged that by their means the mechanical forces of nature can be compelled to do work accompanied by certain determinate motion". In this context, his use of machine is generally interpreted to mean mechanism.
The combination of force and movement defines power, and a mechanism manages power to achieve a desired set of forces and movement.
A mechanism is usually a piece of a larger process, known as a mechanical system or machine. Sometimes an entire machine may be referred to as a mechanism; examples are the steering mechanism in a car, or the winding mechanism of a wristwatch.
However, typically, a set of multiple mechanisms is called a machine.

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  1. S

    Evolutionary mechanism for diversification

    I read an interesting article in the national geographic which stated that a possible mechanism for diversification in evolution might be inside organisms themselves. The article stated that there was an anomoly in the diversity of a selectly breeded chicken population. With the selective...
  2. marcus

    What Are Rosswog's Ideas on the GRB Mechanism?

    Stefan Rosswog has some ideas about what causes GRB (gammaray bursts) He and Daniel Price have a recent article in Science journal about it, and they have some stunning movies of two neutronstars spiraling into merge. I could not find the Science article---the most recent Rosswog---online. It...
  3. F

    A catalyst changes the mechanism of a reaction

    I know that this one can't be a. or c. which is true but, i think its either b. or d., does a catalyst change the mechanism of a chemical reaction ? Which statement is not correct regarding the function of a catalyst? a. A catalyst lowers the activation energy. b. A catalyst changes...
  4. wasteofo2

    The scientific mechanism for accepting one theory over another.

    Are there any sort of essays or generally accepted criteria for accepting one theory over another? I ask, becuase for most any theory, it seems that you can find evidence for it. If you did your research, you could come up with tons of evidence for a totally wrong theory (like all the evidence...
  5. S

    Work Done by Elevator Lifting Mechanism

    A 2000kg elevator rises from rest in the basemtn to the fourth floor, a distance of 25m. As it passes the fourth floor, its speed is 3.0 m/s. There is a constant frictional force of 500N. Calculate the work done by the lifting mechanism. I tried doing v2square = v1square + 2ad and i get 0.18...
  6. H

    I want to know the microscopic mechanism of electric polarition of amorphous

    Who can tell me the microscopic mechanism of electric polarition of amorphous,such as Si3N4 or SiO2.Which dominates the permittivity of amouphors,is it Eletronic polarization,orientational polarization,Atomic ploraization or something others?thank you.
  7. H

    I would like to know the mechanism of LCR bridge

    Who can tell me the theory about the LCR bridge to measure capacitance?
  8. K

    Mechanism of a cylinder rolling down a ramp?

    Hi guys... Can anyone hlp me with the mechanism of a cylinder rolling down a ramp? Here's my understanding about the problem. Can anybody corrected me? If the CM is located at point O (the center of the cylinder), then the torque of for the rotational mechanism is provided by the friction force...
  9. A

    What is the mechanism for demercuration of organomercurial alcohol?

    Can someone point me in the right direction to find a page that gives the actual mechanism for this reaction? My book just says "... demercuration, to remove the mercury. Sodium borohydride replaces the mercuric acetate fragment with hydrogen. Then it gives the reaction 4 organomercurial...
  10. C

    How Does UV Light Initiate Chlorine Atom Splitting in Chlorination?

    Chlorination mechanism... In chlorination, with chlroine gas and methane, why does the UV light cause the chlorine atom to split into free radicals? I know that it "supply the energy", but what actually happens? Thanks. :wink:
  11. N

    Intracellular Mechanism of IGF-1

    IGF-1 has been shown to increase regeneration of nerve cells. I have seen the studies, but am unable to find the actual mechanisms. Does anybody have any information on this or know where I could find it. I have look through my cell and molecular biology book, but can not seem to find it...
  12. chem_tr

    What do you make of this mechanism?

    Hello, I think the one I drew and included in the attachment is valid for Michael-type addition reactions. Do you make a favor to check the mechanism? I think, the steric hindrance of the more-stable carbocation in vinyl group can not participate in this type of mechanism, it is further...
  13. J

    Mechanism for methylbenzoate, help

    Methylbenzoate reacted with excess phenylmagnesium bromide, forms the salt of triphenylmethanol. I need help figuring out this mechanism.
  14. agro

    The Mechanism of DNA Replication

    I once read a 1997 physics book. At the end of the 'static electricity' chapter, it explains the mechanism of DNA replication and protein synthesis (in which static electrical force plays a critical role). However, it says something like 'this model has not been seen in action. It is consistent...
  15. N

    Published proof of gravitational mechanism

    Electronics World, October 2004, Vol. 110, No. 1822: Page 55 summary of gravity as per http://nigelcook0.tripod.com/ The outward motion of matter in the big bang causes an opposite motion of the fabric of the continuum of space, flowing around fundamental particles to fill in the vacated...
  16. V

    Is there a mechanism for reproducing universes?

    Just recently Hawking rejected baby universes; the mechanism was that black holes would spawn a new dimension unseen from our universe. Smolin first proposed this idea, and as far as I can tell in recent discussions between Susskind and Smolin he still believes in it. Susskind had argued...
  17. A

    Exact mechanism of Casimir force

    Do we actually know exactly how the Casimir force is produced, or is this still something to be researched? I know the plates block out some of the vacuum flactuations modes, so the "pressure" outside the plates is more than the "pressure" inside the plates. But how does this "pressure" form? Is...
  18. W

    Mechanism of Most Chemical Reactions

    A Rule of Thumb: "Higher Electronegativity seeks bonding with Lower Electronegativity" Before completing my PhD in organic chemistry, with a minor in inorganic, some 20 yrs ago, I realized that the main mechanism for most organic reactions and most inorganic reactions was one of negative...
  19. D

    Exploring the Mechanism of NETSTAT -A: Last-ack, Fin-wait-1, and Syn-send

    Can you tell me what the mechanism of da command "NETSTAT -A" is ? and in the state column, i have seen Last-ack, Fin-wait-1, syn-send What are they, and how are they created sytematically in actuallity ? Would you please give me examples to prove anything you say too ? Being without any...
  20. T

    Are There Alternatives to the Higgs Mechanism for Explaining Spontaneous Symmetry Breaking?

    Are there any other mechanisms apart from Higgs mechanism that explains the spontaneous symmetry breaking making photon massless and W and Z bosons massive? Do you really believe in the Higgs mechanism?
  21. N

    Gravity mechanism predicts G to within 1.7%

    Proof that gravity constant G = (3/4)(H^2)/[(pi)(density)e^3] The acceleration of matter outwards in the big bang is a force (Newton's 2nd law) requiring a reaction (Newton's 3rd law). The reaction is the inward directed force of gravity carried by the fabric of space. Proof of 1.7%...
  22. B

    Physical mechanism for decoherence?

    i know very little quantum mechanics and would appreciate as qualitative a reply as anyone can muster... what is the physical mechanism for decoherence? decoherence sounds like a solution to quantum 'weirdness' if i understand it correctly...you have to take into account a myriad quantum...
  23. 4

    The Mechanism of Falling Object: no gravity

    The mechanism of falling object is always an interested topic. Almost all physicists think that gravitational force acts on object and makes it have weight and free fall. Here a very simple experiment negates the above parlance. Galileo demonstrates that different mass bodies increased their...
  24. D

    Can the Hubble Expansion Explain the Mechanism of Gravity?

    If you read the editors notes about a book called Pushing Gravity (http://redshift.vif.com/BookBlurbs/PushingGravity.htm ) it tells you of a theory that describes the mechanism of gravity: "The basic idea runs like this. Space is filled with minute particles or waves of some description which...
  25. enigma

    Anyone know of a good 'slot' mechanism tutorial in Pro-E?

    I'm having a heck of a time trying to define limits of motion for planar connection mechanisms. Does anyone know of a good tutorial so I can see how they're supposed to be assembled?
  26. A

    Ground Level Ozone Production: Reaction Mechanism

    Hi, I need help with the following question: What are mechanisms of reactions that lead to the production of ground level ozone the chemical reaction is sunlight + VOCs + NOx -> Smog and Ozone can someone tell me waht the mechanism is or how to develope the mechanism
  27. Vladimir Matveev

    Semiconductor Mechanism for Protein Diffusion

    Hand-to-Hand Model for Tropomyosin Fast Diffusion. Semiconductor Mechanism for Diffusion of Tightly-Binding Proteins: http://actomyosin.narod.ru/h2h-model.htm Would you be so kind as to recommend me some expert who could be interested in view a possible semiconductor mechanism for...
  28. wolram

    What is the mechanism for expansion

    if space is expanding and we take it that it is quantasized into Planckian units of invariant dimensions what is the mechanism for expansion, do these Planck quanta multiply? or have i misunderstood the concept?
  29. S

    What mechanism does it make hair dye product works on hair?

    I want to know what mechanism does it make hair dye product works on hair? Does it work only by coating on the hair surface or any special alteration of the bonding in hair? and beside I want to ask there are products on the market such as "hot rod" which by means of electricity turn into...
  30. T

    Carbonic acid formation mechanism

    Hi. I was reading through my organic chemistry book and they had a little piece on carbonic acid. So CO2 reacts with water and produces carbonic acid, very nice, I read about this before. But now that I've been enlighted with organic chemistry and the idea of mechanisms behind every reaction I...
  31. D

    Reaction Rate of 4HCl + 4NaS2O3 -> Effects on Reaction

    I experimentally determined the reaction rate of the following reaction: 4HCl(aq) + 4NaS2O3(aq) -> 4NaCl(aq) + 3S(s) + 5SO2(aq) + 2H2O(l) and found that the rate was proportional to [NaS2O3]^1 and [HCl]^2 I know that it's probably too tricky to determine the reaction mechanism or rate...
  32. 2

    Why did the red color fade in the reaction between substance x(2+) and y(2+)?

    Year 11 chemistry problem the whole class is stuck on and our regular teacher is away for a month: A strip of substance x(2+) is placed in a red solution of y(2+) (aq). After 3 hours the red colour becomes less intense. There is no change after this. Some x(2+) still remains. a) write a...
  33. wolram

    Antikythera Mechanism: Ancient Device Ahead of its Time

    http://www.giant.net.au/users/rupert/kythera/kythera3.htm The geared wheels within the mechanism were mounted on a bronze plate [third from right on preceding page]. On one side of the plate we can trace all the gear wheels of the assembly and can determine, at least approximately, how many...
  34. M

    What Triggers the Yuck Mechanism?

    The "Yuck" mechanism. What is it that makes one person (me, in this particular instance) detest the very thought of green beans, while another person - of very similar genetic makeup (my sister) - absolutely loves them? What is it that makes me completely sick to my stomach, when I see the...
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