What is Crank: Definition and 84 Discussions

A crank is an arm attached at a right angle to a rotating shaft by which circular motion is imparted to or received from the shaft. When combined with a connecting rod, it can be used to convert circular motion into reciprocating motion, or vice versa. The arm may be a bent portion of the shaft, or a separate arm or disk attached to it. Attached to the end of the crank by a pivot is a rod, usually called a connecting rod (conrod).
The term often refers to a human-powered crank which is used to manually turn an axle, as in a bicycle crankset or a brace and bit drill. In this case a person's arm or leg serves as the connecting rod, applying reciprocating force to the crank. There is usually a bar perpendicular to the other end of the arm, often with a freely rotatable handle or pedal attached.

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  1. M

    Maximum Velocity of a Con-Rod with Off-set Crank.

    How do you calculate the Maximum Anglular Velocity (and angle at which this occurs) of a connecting rod which uses a slider-mechanism with an offset crank? ω = 300 rpm, 10\pi rad s-1 crank shaft, r = 50mm (0 → A) connection rod, l = 200mm (A → B) When crank angle = 45 degrees, the...
  2. P

    Convert crank driven system to an air piston one

    Hi!, nice place you got yourselves here, so I'm a mechanical engineer working as a maintenance supervisor working for a dairy and food corporation specializing in UHT milk and milk derivatives (varietieshttps://www.physicsforums.com/Nexus/editor/menupop.png of yogurt, cheese, butter, ice cream...
  3. B

    Slider crank mechanism. Help needed to find the velocity & angular velocity.

    Homework Statement The instantaneous configuration of a slider crank mechanism has a crank GH 10cm long, the connecting rod HP is 50cm. The crank makes an angle of 60 degree with the inner dead centre position and is rotating at 110 rev/min. Determine the velocity of the piston P and the...
  4. K

    F=ma applied to slider crank piston motion

    I'm struggling to apply F=ma to the motion of a slider crank, more specifically the piston. I want to find out how much force is nessesary to keep the piston in motion. Essentially, in the mechanism there is acceleration and deceleration, does that mean only at some points in the cycle there is...
  5. H

    Calculating Torque of a Crank Mechanism

    Hi, Im currently designing a small machine which uses a simple crank mechanism but my crank mechanism is not a typical one. My application: [/URL] My application uses the crank wheel to drive the block (10kg). Hence, I need to calculate the torque require to drive the crank wheel. So I can...
  6. J

    How to Create a Hand Crank for 24000rpm DC Motor

    I want to create a handcrank to spin a DC motor at 24000 rpm. The DC motor is an 18V hobby motor from radioshack. Is this possible?
  7. J

    If I wanted to create a hand crank to spin this dc motor

    If I wanted to create a hand crank to spin this dc motor... I want to create a handcrank to spin a DC motor at 24000 rpm. The DC motor is an 18V hobby motor from radioshack. Is this possible?
  8. J

    How can I build a hand crank generator to power a universal powermat?

    Alright, so I am building a hand crank generator, and my goal is to replicate the K-tor pocket socket. http://www.k-tor.com/ The goal is to power a universal powermat with the generator. I need to produce 10watts at 120volts, and my group is completely lost. If anyone could provide...
  9. M

    Hand crank generator battery charger circuit

    Hello, I want to use a DC permanent motor as a generator in order to use it to charge a battery. This generator will be rotated by hand. The speed is varying as it rotates by hand. I would like to know what is the circuit that I could use it to charge 12 V chargeable batter? Best wishes,
  10. B

    Crank Slider Mechanism 3d movement question.

    Hi. This maybe common sense to some of you but I am racking my brain to find away to solve this one. I would like to pull a lever on one axis and move a slider on a different axis . So by pulling a lever towards me, I move a slider left and right. Is this possible without ball joints...
  11. F

    Increasing Torque, Force, and Work: Increasing crank Length (L)

    Homework Statement You are pulling water with a constant velocity from a well using a crank of length L. If the length of the crank was doubled, you could ... Homework Equations Work = Torque*angular distance Torque = I*angular acceleration Torque=F*d*sin(angle) It looks like the...
  12. W

    Solving Schrodinger Eq. w/ Crank Nicolson Method

    I have tried discretizing the Schrodinger equation using the crank nicolson method and then have tried to solve the resulting tri-diagonal matrix using the algorithm on Wikipedia. http://en.wikipedia.org/wiki/Tridiagonal_matrix_algorithm However, I am not getting the required result and...
  13. R

    Crank Nicolson Stability

    Hello, I was wondering about teh stability of the Crank Nicolson method as compared to the forward time center space central difference method of solving differential equations. In particular, I was wondering the the stability criteria used for the central difference method, stability =...
  14. D

    How can I design a linear to rotational crank mechanism without using gears?

    I'm looking for a crank that can give me linear movement to rotation (not the other way around). There is a component that I'm aware of called a uni-directional drive that turns rotation movement in either direction into movement in only on direction... stick a rack in the mix and there is...
  15. D

    Space saver compartments with mechanical crank device

    Greetings. I am a woodworker, and i build lockboxes with hidden compartments and complicated homemade magnetic locks. On my current lockbox, i am trying to design a "box of compartments", 16 compartments to be precise. included is a quick top view (looking down) design. there are actually 15...
  16. B

    Slider crank mechanism mass moment of inertia

    I need help solving a mass moment of inertia for a slider crank mechanism. I've done my best to sketch it in the attachment. This will be used for sizing of a motor. Homework Statement Link A has mass Ma and is located Acg distance from its pivot point Z Link B has mass Mb and is located Bcg...
  17. P

    Optimizing Gradient Descent with Crank-Nicholson Scheme for Stable Convergence

    Hi everyone, This is more of a numerical question but I felt this would be the most appropriate forum. I apologise if it is not. I have a gradient descent problem of the following form: \psi_{n+1}=\psi_{n}+\alpha(\nabla\psi_{n}*D^{2}\psi) I am trying this on a 256x256 image grid...
  18. R

    Inertial forces in crank slider mechanism

    I was little confused about taking inertial forces into significance while calculating piston effort in a piston crank slider arrangement. I read an analysis of various forces acting in a piston cylinder arrangement in a book yersterday, and while calculating piston effort(net force on piston...
  19. K

    Designing a Low Speed Crank Mechanism: Counterweight Calculation

    heyy...i'm designing a crank for a mechanism...and i need to counterweight it...is there any formula which tells u how much counterweight to add...its a low speed mechanism and very light...material mostly plastic or wood
  20. D

    Solving Slider Crank Problem: Tips & Advice

    I'm having trouble figuring out this problem. I know how to solve the problem if the angular velocity was known but there seem to be too many unknowns to be able to generate graphs. If anyone can offer advice that would be great.
  21. MTd2

    Space time signature as a quantum number and antigravitaion (nothing crank here)

    http://arxiv.org/abs/0909.3456 Antigravitation Sabine Hossenfelder (Submitted on 18 Sep 2009) We discuss why there are no negative gravitational sources in General Relativity and show that it is possible to extend the classical theory such that repulsive gravitational interaction occurs...
  22. C

    Modeling Mechanisms with Working Model 2D: A Simple Solution for Engineers

    (different guy using the same user name) I am looking for a simple engineering software to model crank and rocker, gear, crank and slider, worm gear, scotch yoke, cam and other generic mechanisms. Most important is crank and rocker. Maybe some hydraulics and pneumatics. Something my...
  23. B

    Proving a 2D slider crank mechanism fits the Gruebler's Equation

    Homework Statement Need to prove that a slider crank mechanism fits the Grueblers eqaution, already done for a four bar mechanism no problem, however having some serious problems with the slider crank. If l is the number of links and j is the number of joints Homework Equations Grueblers...
  24. T

    Optimizing Pedal Crank Forces for Efficient Cycling: A Square Wave Approach

    I am trying to determine the forces exerted on a bicycle pedal crank by the rider so I can analyze the fatigue. I believe that I understand how to conduct the fatigue analysis but I think that the forces on the bike crank are more complicated then I have assumed them to be so far. I know...
  25. M

    Consistency of Crank Nicolson method

    Homework Statement Analyze the consistency of the Crank Nicolson method: u_n+1 = u_n + h/2[f_n + f_n+1] where f_n = f(t_n, u_n) Homework Equations How does this method work if you have to have u_n+1 to calculate f_n+1, and vice versa? Which comes first? The...
  26. C

    Crank That Sigma Boy: A Math Parody

    A parody of Crank that Soulja boy... about math =). There was very little choreographing done, so bear with it. I hope you like it. The lyrics are in the "about this video".
  27. tandoorichicken

    How Can You Design an Effective Hand Crank Generator?

    Hello all, I have to design a hand crank generator to produce power for some downstream application. The amount of power is on the order of that needed for anything between a heavy-duty flashlight to one of those desktop mini-fridges that hold one soda can. Thing is, I'm drawing a blank on...
  28. A

    Constructing a Crank and Slotted Lever Mechanism in 3 Days

    hey i have got to make a scaled model of any mechanism that we see around(or maybe we don't sometimes) in the machine shop in under 3 days as our summer training project. we are provided with all the raw stuff and machines that one usually sees in machining shop. i have decided to make a crank...
  29. L

    If you crank a generator in space

    I am confused about where the electrons come from when electricity is generated. Is it from ambient air? So this means A generator would not work in space?
  30. D

    Torque crank and bucket question

    Homework Statement A bucket filled with water has a mass of 70 kg and is attached to a rope that is wound around a 0.035 m radius cylinder. A crank with a turning radius of 0.35 m is attached to the end of the cylinder. What minimum force directed perpendicularly to the crank handle is...
  31. C

    Solving for Fp: Bucket and Crank Problem with Unknown Forces

    I have a problem of two parts which I don't know what formulas to use. I would be greatful if someone could help me with it: A bucket with the mass M is hanging in a cord with the length of L which in turn goes over a pulley with a diameter of D. The pulley has a crank with the length x. The...
  32. R

    What is a Four Bar Linkage and How is it Used in Machine Mechanisms?

    anybody knows about 4 bar linkage?? there's a crank and slider mechanism and i need help... i would like to know more about the crank slider and what is it made of?? what is that slider made of?? roller?? 2 bars and a square metal?? help! thanks alot...
  33. S

    The most detailed and thorough ether-type crank theory I've seen

    the most detailed and thorough ether-type "crank" theory I've seen although I adore both naive and reasoned scientific [or philisophical] rebellion and creativity- I don't really buy these ether/plasma crackpot-esque cosmology type theories [ I think there is a lot of straw-men and incompatible...
  34. P

    How Do Hand Crank Power Devices Work?

    I've seen them on radios, cell phone charges and flashlights. I haven't seen one in person, but I just want to get an idea of how they work. I'm guessing some massive gearing and a small generator/motor? And what does it use to store the energy? Or is it stored mechanical energy? Thanks Philip
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