Mechanism Definition and 533 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. C

    Mechanism that only rotates when driven from one side

    I have a geared DC motor taken from a hand drill. When I manually turn the internal motor, the drill bit rotates. This can be done in both directions. However If I try and turn the drill bit it does not rotate. What is the mechanism called that achieves this? My friend says it is a sprag...
  2. S

    Explaining Universe Expansion Through Gravity & 3D Geometry

    Hi, This is my first post and I've joined simply to see what anyone may make of the following idea. Given the relatively recent depictions of the universes 3d structure as something akin to nodes with filaments connecting them. It seemed that the expansion of the universe could be explained by...
  3. P

    Arm blade mechanism for Cosplay

    Hello everyone! I'm making a costume of a game character and I think I need some guidance regarding the mechanical aspect. I asked this question on a cosplay site, but they suggested I might get more help here. So I'm going to cosplay this character on an anime convention: As you may have...
  4. N

    Charge of the W bosons in the Higgs Mechanism

    I am confused about how the gauge boson W+ and W- get their charge under spontaneous symmetry breaking in the Higgs mechanism. Here's what I have so far: The covariant derivative for a SU(2)⊗U(1) is DμΦ = (∂μ + igWμiσi/2 + ig'Bμ)Φ where g and g' are coupling constants. SU(2) is associated...
  5. Y

    Angular Velocity and Acceleration for Elevator Mechanism

    Homework Statement In a charming 19th-century hotel, an old-style elevator is connected to a counterweight by a cable that passes over a rotating disk 3.50m in diameter (the figure (Figure 1) ). The elevator is raised and lowered by turning the disk, and the cable does not slip on the rim of...
  6. M

    Synthesis of a four bar linkage with a ternary couplar

    Hi there! Currently i am trying to design a four bar linkage for a bicycle rear shock. You can find this linkage at here http://ffden-2.phys.uaf.edu/211_fall2010.web.dir/Michael_Stanfill/VirtualPivot.html This linkage is called virtual pivot point. Critical part of this design is to achieve a...
  7. Vinay080

    Unraveling the Mystery: How Do We Sense Heat?

    Does the kinetic energy of molecules make us feel a substance to be hot? I want to know the mechanism through which we feel something to be hot. How the molecules come in contact to our skin molecules and interact with them to send message to our brain through neurons? How the brain atoms...
  8. AryaUnderfoot

    Water Flow & Pressure: The Impact of Water Control Mechanisms on Overflow Time"

    Water is poured into two containers separately at two different rate. Will the rate of increase of water flow affects the pressure building up? Can the pressure affects the time taken for the water to overflow the container? ( One of the container is designed to avoid overflow, hence the rate...
  9. T

    Parameters for a four bar mechanism

    Homework Statement I am given a four bar mechanism and the mathematical representation of a point on the coupler I am looking for ways to determine the lengths of the linkages from this information? Homework EquationsThe Attempt at a Solution I really have no idea
  10. A

    4 in lift mechanism using a continuous servo?

    Hi, I need to design a lift mechanism that is powered by a small continuous servo. It needs to lift a plate up at least 4 inches, and be totally powered by this servo...
  11. R

    Is there any mechanism for learning p block reactions?

    Do we have to rote memorize it or is there mechanism so that we can learn it easily? There are some ion exchange reactions which are simple like NaCl + H2O-------> NaOH+ HCl. but for example what about this? P4 + NaOH + H2O----> ?
  12. C

    Mechanism for Phosgene Formation

    The overall reaction for the formation of phosgene from Cl2 and CO is: Cl2 + CO --> Cl2CO The mechanism is: Cl2 + M <--> 2Cl' + M Cl' + CO <--> ClCO' ClCO' + Cl2 --> Cl2CO + Cl' For this mechanism, the sum of the elementary reactions is: 2Cl2 + CO --> Cl2CO + 2Cl' However, doesn't the sum...
  13. H

    How can I create a simple latch mechanism using a roller chain for my project?

    I'm looking for a simple latch design. My project will have two roller chain sprockets positioned one above the other with about a two foot gap. A motor will turn one of the sprockets and the other is just an idler sprocket. A #40 roller chain will run around the two sprockets. Mounted just...
  14. P

    What is the Mechanism of Trinitration of Phenol?

    What is the mechanism of trinitration of phenol ? Is it one by one substitution of nitro groups ? For which wouldn't the nitro groups stop the reaction as they are deactivating groups Or is it the simulataneous activation of ortho and para positions of phenol and the nitro groups add on...
  15. Thom Stoops

    Need Help Designing Mechanism for Automatic Spring Return

    I'm trying to design an entirely mechanical system for returning an extension spring to its extended state, without the assistance of electronics, pneumatics, hydraulics or any other form of auxiliary power. It's for a soft exosuit concept that simply enhances the speed and ease of walking or...
  16. Safinaz

    Seesaw Mechanism: A Quantum Field Theory Study

    Hi all, I think it's just an Eigenvalue preoblem. I'm studying Seesaw mechanism from http://www.quantumfieldtheory.info/TheSeesawMechanism I don't get how he substituted in equ. 21 for N Eigenvalue from equ. 20, that ## \frac{m_D}{m^R} ## is a factor of ## \nu_R ## not ## \nu_l^c ## ? Any help ..
  17. S

    Oleum Fuming: Investigating the Physical Mechanism

    I'd like to know the physical mechanism of oleum "fuming" on its surface. Dissolved SO3 reacts very exothermically with some air humidity. Why does the mist occur instead of dissolving created H2SO4 in the solution?
  18. gfd43tg

    Proposing a reaction rate mechanism

    Homework Statement The rate law for the reaction is found from experiment to be Suggest a mechanism consistent with the rate law. Homework EquationsThe Attempt at a Solution Here is the webpage with the solution http://www.umich.edu/~elements/07chap/frames.htm Here is the solution Rate...
  19. jmay4096

    Need Help Understanding Mechanical Advantage of Chain Mechanism

    Hi guys and girls this my first post! Hope i got it in the right place. I need help understanding the mechanical advantage of this mechanism. The top sprocket is the input power the bottom sprocket is an idler the attachment on the chain is the output. Help!
  20. Q

    What is the correct mechanism for saponification?

    Homework Statement Problem: I am told that the first mechanism is operative in saponification. The Attempt at a Solution However, this strikes me as wrong because the first mechanism involves the formation of dianion. Using hydroxide ion to abstract a proton and make that particular...
  21. L

    How Does d-d Transition Occur with No Free Higher Energy d-Orbitals Available?

    how does d-d transition take place when there are no free higher energy level d-orbital's left(as the only two higher energy d orbitals form coordinate bond with CN-?
  22. C

    Coriolis Acceleration of a Mechanism

    Homework Statement Rod AB rotates with the angular velocity and acceleration CCW as shown. Points A and D are pin connected. The collar C is pin connected to the link CD and slides over the link AB. At the instant shown the link CD is vertical and the link AB has an angular velocity of 2 rad/s...
  23. Z

    Kinematics of pantograph device

    I need to obtain the forward and inverse kinematics of a pantograph device. It is easy when only the one side of the pantograph is considered; So, it becomes a 2DOF planar elbow mechanism, which is easy to solve. However, there is symmetry on pantograph, so I kinda need to combine two planar...
  24. L

    Need mechanism for connect from handle to controlled object (please see pic)

    Please see the above picture, I need a mechanism to connect handle to a controlled object below. While the handle moves from a to b (~10cm) the object needs to move from c to d (about 25 - 30 cm) and when handle moves back from b to a, the object needs to moves back from d to c. They are both...
  25. M

    Explaining the mechanism of a reaction and drawing its Energy diagram

    Homework Statement This was a lab. I started with Maleic Acid. We performed a temporary corbonication to see whether or not the single bond would rotate to create fumeric acid, maleic acid or both. The question that I have to answer that I cannot answer is: Explain the mechanism of the...
  26. J

    What is the best method for designing a trigger system for a ball launcher?

    Hi, I'm working on a project, the project is to create a ball launcher. the ball being a squash ball. 3 balls must be loaded once only but be able to be fired individually. the energy used to fire these balls is 3 1m long bungee chords. this cannot be changed. there are 3 main parts to it.1...
  27. enorbet

    Mechanism for Real "Zombies" in the Animal World

    Greetings I don't know if this is the right place to post this because I'm not certain how it is classified or if it can come under many headings. So please move this if it is better suited elsewhere. I watched a video on pbs.org a few years ago and since I am just now writing here about...
  28. T

    Does the Higgs Mechanism Influence Gravity in the Same Way for All Particles?

    I understand that Higgs mechanism “gives” mass to particles in QM sense. My first question is, why it also gives mass in GR sense, bending space-time? Of course, I don’t expect an answer now as it is definitely a TOE/Quantum gravity territory. However, let me rephrase my question in a narrower...
  29. B

    How Can a Sensor Accurately Control Inflation to 2 PSI?

    Hello all, I am trying to design a system with a sensor that can detect when an inflatable is inflated to 2 PSI. I am trying to inflate something small, around 6 liters. I currently have a system that uses a solenoid, the compressed air, and a mechanical timed relay that tells the system when...
  30. gauss44

    Why doesn't this reaction use an E2 mechanism?

    tert-butyl bromide + MeOK in MeOH -----> I would think that MeOK would dissociate in solution making it MeO- which would be strong enough to yank a proton off tert-butyl bromide and initiate an E2 reaction. Where am I going wrong? PS - I am a tutor who hasn't done organic chemistry for a...
  31. spacecadet11

    Exploring the Mechanism of the Higgs Boson and Its Potential Control

    Hello. Since the Higgs Boson is responsible for giving sub-atomic particles mass..or any particles there mass..is there a present understanding of the mechanism by which the field actually does this? And if there is...is there any artificial way of controlling it? My thinking is that if you...
  32. agnishom

    Does the Higgs mechanism explain the equivalence of gravitiational and

    I am not well versed in the idea of Higgs mechanism. However, I was wondering if it does explain the problem of equivalence of gravitational and inertial mass. Also, what is the modern accepted definition of mass?
  33. jmex

    Airfoil Mechanism: Exploring Lift & Drag Forces, Angle of Lift & VAWT

    Hello, I read about airfoil mechanism that there happens to be pressure difference created above and below the airfoil which result in lift force. My questions are: 1. What actually happens in the speed of air. I mean how can one side of the air travels with greater speed when they have the...
  34. S

    Retraction Mechanism for threaded nut

    Hi, I have been trying to find all the retraction mechanisms possible to bring the nut back on the threaded shaft when it comes forward. Constraint is geometry. Between the back of nut and the face of the threaded shaft, space is max. 6 mm. also, the nut moves only 2 mm forward on shaft...
  35. T

    Mechanism of Intake Pumping Losses

    I'm a mechanic and I'm debating the exact mechanism of the so called "pumping losses" or "pumping work" of conventionally throttled 4 stroke spark ignition engines. We know that EGR is employed to reduce intake pumping losses and actually increases engine efficiency for slightly better fuel...
  36. B

    Crystal Radios - Understanding The Tuning Mechanism

    Hello, I bought an electronics kit for my 12 year old brother (and perhaps a little for myself too...) for building a crystal radio. I would like to understand what's going on when I tune the radio, so that I can explain it to him. It's a simple setup, where changing the position of a...
  37. R

    Does steam deaeration involve Henry's Law?

    On many boiler feed-water systems there are deaerators which essentially sparge steam through the water. Why does steam deaerate water? Is this simply a temperature effect on gas solubility? Or something else?
  38. J

    Why was confirming Higgs mechanism worth it?

    I'm just looking for a layman's explanation of why the efforts to confirm Higgs was truly necessary and worth the expense. The counter-argument is that theoretical physics seem to be going along just fine assuming something like the Higgs mechanism existed without validating it. Also, nothing...
  39. Dotini

    Solar Wind Modulates Lightning - Mechanism Unknown

    http://iopscience.iop.org/1748-9326/9/5/055004/article http://www.bbc.com/news/science-environment-27406358# Activity on the Sun is sparking lightning strikes here on Earth, a study suggests. The finding was surprising, said Dr Scott, because it had been thought that an increase in the...
  40. B

    Neutron Stabilization mechanism?

    If a neutron is unstable outside the nucleus, then what makes it stable within the nucleus? Does the binding of particles together somehow make them stable? Neutrons decay via the weak force, but are bound in the nucleus by the strong force. Does the strong force inhibit the weak force...
  41. Kkangliu

    How could Einstein's theory contradict to the quantum mechanism?

    We all know that Einstein's theory apply to the big universe, and quantum mechanism apply to the nanoscopic scale, and both theory work perfectly in it's realm, but how could two theory contradict each other?
  42. S

    Mechanism of benzene nucleophilicity activation

    I have some questions how various substituents are transfering benzene conjugated (π) electrons (i.e. activating/deactivating). As usual, no chemist provides an explanation. 1)As I see, the first important thing when forming a carbocation during electrophilic aromatic substitution is to find...
  43. M

    Missing technique used to find acceleration of a 4-bar mechanism?

    Hi there! There is a technique that is being used by my lecturer for mechanisms course at uni and i could not understand how this technique is manipulated.I wish i would know this methods name but no chance!. This technique is being used to find normal acceleration of link in 4-bar...
  44. A

    The 'mechanism' of length contraction

    Let's suppose that we have a rod which is 2 meters long in its rest frame. Its rest length can be defined as a set of points which do not occupy the same place, measured in a frame which is at rest with the rod as a whole. Now if we travel relative to the rod, it gets length contracted, I...
  45. P

    Analytical kinematics of a 6-bar mechanism

    Homework Statement This is a mechanism I'm working with for my undergrad project (its Modelled in Msc ADAMS) https://www.flickr.com/photos/35430110@N04/13902494524/ https://www.flickr.com/photos/35430110@N04/13902494524/ And to give you an idea of how it operates; position 1...
  46. P

    The Higgs field (mechanism) is the cause of fictitious forces?

    Newton second law of motion states that acceleration is produced when a force acts on a mass. The Higgs field (mechanism) is the cause of fictitious forces?
  47. ChrisVer

    Initiating mechanism of supernovae

    I think that our current knowledge on the initiating mechanism of supernovae is that they happen due to neutrinos interacting with the inner layers of a star and then accelerating them away from the core. I am having some trouble in understanding that idea. Of course this could be plausible if...
  48. H

    Launching Mechanism: Design & Build for 400 Gram Projectiles

    Hello folks, I have very little robotic experience, so would like to start my knowledge accumulation here at PhysicsForums. I am trying to design and build a launching mechanism to launch a 400 gram projectile. I was hoping to get a bit of guidance in what devices I should be looking into...
  49. D

    Energy production mechanism using capillary action

    We know that water rises in a glass capillary owing to the surface tension phenomenon. If we make an arrangement as shown in the attachment, (read Water instead of mercury in the attachment, I got confused there) & do the following procedure. The valve at the bottom is open, & the one at the top...
  50. M

    Determining the loops in a mechanism

    how can we determine the loops in this mechanism.
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