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

    Engineering Kinematic modelling of a mechanism (General Crank)

    Hi, I was wondering if you could help me with a job at the university that consists of the kinematic modeling of mechanism number 3 in the image attached to this message. I have to set up the constraint equations and then solve the position, velocity and acceleration problem. For now I would...
  2. bmhiggs

    Recharging a Battery With a Hand Crank?

    Could a normal rechargeable battery (meaning the kind you plug into a usb port or electrical outlet) be recharged with a hand crank generator (assuming it was generating a sufficient voltage)? Would there need to be some kind of converter to make it possible, or just connect some +/- leads? I'm...
  3. D

    Resultant pedal force (FRESULTANT) Force tangential to the crank arm

    %% part 1 clear all; close all; clc; torq_crPK = zeros(10,1); ang_tqPK = zeros(10,1); ang_powPK = zeros(10,1); torq_crDS = zeros(10,1); torq_crUS = zeros(10,1); WD = zeros(10,1); WDpos = zeros(10,1); WDneg = zeros(10,1);%% INPUT VARIABLES for i=1:10 % cyclist number % read in the...
  4. H

    I Crank Nicolson method to solve a PDE

    Hello, I wrote a code to solve a non-linear PDE using Canrk nicolson method, but I'm still not able to get a correct final results. can anyone tell me what wrong with it?
  5. I

    Slider Crank Force Analysis: Understanding the Equilibrium Forces and Results

    I am in a mechanical design class that has been focusing on the slider crank mechanism. My professor tends to just provide derived equations without showing the analysis. I feel like I am missing out on some key understanding because of this. Specifically, I am trying to do what should be a...
  6. M

    Equation for the angular position of a slider crank mechanism

    Hi! I would like to know how I could define an equation for α with given the two lengths of the rods and angle theta (θ). I sketched the situation below, the problem arises when the rod Lab has pasts the 180 degrees. Like to hear.
  7. subatomicprincess

    Question about Slider Crank Mechanism problem

    I have attached my attempt. The only thing I keep getting wrong is the direction of V_(D/B). I know it is perpendicular to r_(BD) but, I never know if it is going upwards or downwards. In this case, I thought it was going downwards but when I checked the answer key, it had said it is going...
  8. bugdry

    Slider Crank Mechanism Torque Question

    I hope that it is okay for me to ask this here. It has been a long time since i did mechanism analysis. I have what I hope is a quick question. I calculate the torque required to rotate crank AB and therefore lift up the link BC to be 88lb-in. I assumed that link AB has no weight, no...
  9. R

    Crank Journal Turning w/ Attached Bar: Does it Ever Stop Moving?

    Basic zero clearance friction-less model of a crank journal turning with an attached bar on that journal. Bar moves up and down in Sine fashion, components of journal Velocity vector change accordingly (showing clockwise rotation here), and Velocity of the attached bar only has a Y component (up...
  10. bash1803

    Understanding Algebraic Solutions for Slider Crank Mechanism Calculations

    Hi Guys, I am currently working on an assignment for my uni. I don't want to post the question right away as I want to try to understand as much of the material as possible; but it seems what they have given me is a bit lacking. As such I was wondering if anyone could point me in the right...
  11. R

    Does thrust get cancelled by a rotating crank?

    I have a frame which supports a crank rotating through 360°. The crank lifts a 30 kg weight 540 times a minute ( 540 rpm). As the crank moves 0° to 90° the weight is accelerated to full speed which means it has thrust but then from 90° to 180° it is slowed to a stop then from 180° to 270° it is...
  12. J

    Angular Velocity Problem — a Piston and a Crank

    Homework Statement I have been set this question and I am struggling with parts b and c. I think I am nearly there but can't quite get over the line. Please could someone give me a nudge in the right direction. [/B] 1. (a) For the mechanism shown in FIGURE 1 determine for the angle θ = 45°: (i)...
  13. H

    What makes a connecting rod turn a crank one way?

    This may be the most awkward unexpected question ever concerning the reasoning for which I ask it. I begin with explaining the reason because I think you should know why I ask this question to begin with so you can understand what underlying basic principle of this mechanic I want to...
  14. S

    Torque and power calculation for a crank wheel

    How to calculate torque and power at 'drive wheel' with following inputs and also requirement shown in below picture- a. Gear ratio, 1: 6 b. Attached 10Kg weight for bigger wheel to make as a crank wheel and diameter is 30inch. c. Bigger wheel: Consider 180 degree is freely rotates(due to 10kg...
  15. CameronRose

    Reducing the power required to drive a slider crank

    Hi folks, I'm currently working on the design of a triplex plunger pump. I have conducted an investigation into the loading of the pump at maximum operating pressure using an analytical method (free body diagrams) and using rigid body dynamics to validate. In both analyses the pump has been...
  16. powdernose

    Mechanical Advantage in a crank system

    I am not a student btw, this is seeking extra knowledge regarding a hobby of mine, and it has been too long since I've tried to solve a physics problem. 1. Homework Statement I have the above system in which Lever L (200mm) applies force to a crank D (diameter 33mm), which has a reverse...
  17. P

    How do I calculate the output curve of a crank?

    I am having a difficult time communicating about concepts without the math. And I have some very specific questions. So here we go with one of them. Regarding a crank mechanism, say with a throw of 10 centimeters, how can I calculate what percentage of a given constant force that is applied...
  18. T

    Black Scholes heat equation form) Crank Nicolson

    Dear all: I am studying the finite difference method for black scholes equation(heat equation form), and my Prof. asked me to use the Crank Nicolson and Compact Scheme to do it. But I cannot reach second order for the space, i.e., x . The error only reach 1st order and sometimes not stable, it...
  19. R

    B If the pedal crank arm length of a bicycle increases....

    You have 2 bikes. They only differ in 1 way. The length of the crank arm (where pedal attaches) https://en.wikipedia.org/wiki/Crankset How will these bikes differ when riding? Is one harder to pedal than the other? Why?
  20. M

    Prove mathematically that the lengths of the crank....

    Homework Statement Design an offset slider-crank mechanism which has the following specifications: 1. Stroke length of slider block C = 150 mm 2. Advance-to-return time ratio = 1.2 3. Offset height h = 50 mm Prove mathematically that the lengths of the crank and of the connecting rod are AB =...
  21. ShaiNaveh

    What is the formula for calculating force in a crank and slider mechanism?

    Hi all, I have a question regarding a simple crank and slider mechanism, but I'm not a mathematician. This means that long formulas scare me... (: I've been searching around and haven't found anything I can really understand. I'm trying to get a "ball park" formula to calculate the amount of...
  22. P

    Rotary to linear motion using a crank

    Hello guys, since linear motors are too expensive I decided to buy a rotational motor and use some gears and a crank mechanism to get enough torque and translate rotation into linear motion. I need to meet a certain force on the shaft though. The question is how do I calculate the resulting...
  23. R

    B Finding Horizontal Force in a Crank at 10N

    I'm trying to establish the force in the horizontal direction of a crank when the force that is tangent to the crank is 10N. Zero degrees is on top of a circle. Clearly, when the crank is vertical which corresponds to it being at zero degrees, the force in the horizontal plane is normal to the...
  24. Alistair McCheyne

    Slider Crank Magnitude and Direction of Force on Member AB

    Homework Statement Homework Equations The Attempt at a Solution https://scontent-lhr3-1.xx.fbcdn.net/v/t34.0-12/13140955_10156888508510486_863100825_n.jpg?oh=3f13a038f3dc053c7a10858aa62f6fc0&oe=57318819...
  25. Alistair McCheyne

    Slider Crank Mechanism Magnitude and Direction

    https://scontent-lhr3-1.xx.fbcdn.net/v/t34.0-12/13181084_10156883800920486_1357045350_n.jpg?oh=a39d7777f01c4aa06301c4f3d740de1e&oe=57301DBC Hi I am currently studying design engineering and my lecturer has left just before an exam. I really don't know how to find the magnitude and direction of...
  26. T

    Design a Crank Mechanism: Solutions & Equations

    I want to design a crank mechanism. I found this page on Wikipedia https://en.wikipedia.org/wiki/Piston_motion_equations Relating from this diagram, is x the max stroke of the piston ?, or is it PO-(max stroke of piston) ? And why is l^2 = r^2 + x^2 - 2*r*x*cos(A) Shouldn't it be, l^2 =...
  27. P

    Shaft and Pin Size of Slider Crank Mechanism

    Hi all, I am working on a slider crank mechanism for moving an object of about 100 kg back and forth 30 mm at about 600 rpm. I plan to attach the connecting rod onto a flywheel that act as a crank, or attach to a pulley (in case need to use a transmission system to reduce input speed, increase...
  28. Mingsliced

    Offset Piston - Calculating Max. Angular Velocity

    Homework Statement After happily working my way through the earlier parts of this question, I'm pretty much at the end of my tether with the last two parts. Please find the diagram attached: A) Determine the value of the angle θ (measured from vertical) when the angular velocity of link AB a...
  29. S

    Crank Slider mechanism analysis

    Homework Statement For the mechanism shown, analytically find A) Velocity B) Acceleration. Of All points (B, C, D, E and G) The lengths of all links are given in the photo. It has to be solved using the analytical velocity and acceleration method. I've attempted so far deriving the equations...
  30. thegreengineer

    Slider crank mechanism problem

    Before starting I want to say that this topic is from a subject I'm taking called vector mechanics. The subtopic dealt is called kinematics of rigid bodies. Homework Statement The wheel rotates around an axis. This point of reference of the center of the wheel is labeled as "A". This wheel...
  31. Y

    Instantaneous center of velocity for a inverted slider crank

    Homework Statement [/B] Find the instantaneous centers of the linkage below. Homework Equations # of ICs = n(n-1) / 2 The Attempt at a Solution [/B] From the equation above, there are 4(4-1)/2 = 6 ICs in this linkage. But one thing I don't understand is how there are 4 links when 2 and 3...
  32. L

    What is the rotational velocity of the crank?

    Homework Statement You accidentally knock a full bucket of water off the side of the well. The bucket plunges 13 m to the bottom of the well. Attached to the bucket is a light rope that is wrapped around the crank cylinder. The cylinder has a radius of 0.085 m and inertia of 4.0 kg. The inertia...
  33. J

    Inertial forces of a slider crank

    Homework Statement Hello, I have an exam later in the week and I'm trying to understand how to this problem. Homework Equations Sum of forces. Sum of moments. The Attempt at a Solution I broke the mechanism into 3 pieces, the crank, connecting rod, and slider and then began to analyze...
  34. S

    Offset crank slider mechanism connecting rod analysis

    Homework Statement A) Determine the value of the angle θ (measured from vertical) when the angular velocity of link AB a maximum. B) What is the maximum angular velocity of link AB. Homework EquationsThe Attempt at a Solution This is a part of a bigger question. I've managed to answer all...
  35. H

    Maximizing Velocity and Acceleration in a Slider Crank Mechanism

    Homework Statement a) For the mechanism shown in figure 1 determine for the angle (45°): i) the velocity (VBO) of the piston relative to the fixed point (O). ii) the angular velocity of AB about point A. iii) the acceleration of point B relative to A. *Note: Link AB is horizontal when angle =...
  36. M

    Calculating Mass Moment of Inertia for Slider Crank | Explained

    Hi, I'm sorry my question is almost identical to an unanswered question here, but I was unable to reply to it (because it is old?). I want to have the mass moment of inertia 'I'of the block C, which will be a function of theta. I am ignoring the contribution from the links.Due to the...
  37. M

    Bicycle Crank Power Meters and Round and Non-Round Chainrings

    One of the debates in part of the bicycling community is whether elliptical or non round chain rings cause a crank based power meter to over report power beyond the power meters accuracy rate when velocity is only measured once per revolution. Average and weight average of the velocity per...
  38. A

    Homemade Electric Crank Generator Not Producing Voltage

    This is a homemade generator I've been trying to make using a hand crank, neodymium magnets and two copper coils. It doesn't work. If anyone has any suggestions on how to configure the magnets or something I am doing wrong your comments will be much appreciated. Thanks!
  39. R

    How to calculate the torque of slider crank?

    As shown in this picture, if Fb, l (length of connecting rod), r (radius of crank) and θ is given, how to calculate the torque the slider crank? I know it can be a simple question for Mechanical Engineering majors, but I am an Electrical Engineering major and have very little knowledge in...
  40. Lksllks

    Landis crank shaft grinding machine

    :cry: is there anybody know about the landis crankshaft machine! I got a knotty problem! Please help!
  41. P

    Building a homemade crank generator, but no voltage on voltmeter?

    Hey guys, I built up this design for a hand-powered crank generator with four neodymium magnets, but am having trouble getting a reading through a voltmeter. I want to try and amplify the voltage as well but that will come later. Here is our setup http://imgur.com/a/0aM4W#0 I am not...
  42. C

    Technical Drawing of Crank Mechanism

    Homework Statement Hey, I have to do my homework in Technical Drawing where we have to describe the function and the assembly of any part. I have got a crank mechanism and I just want to know if I name all the parts correctly. I am not quite sure if everything is correct. The Attempt at a...
  43. S

    Help with engine displacement volume, fuel flow rate and crank angle

    Homework Statement An automobile has a 2.5-litre, four-cylinder, homogeneously charged, direct injected, four-stroke diesel engine. The maximum power output of this naturally aspirated engine is 200 HP at 4000 rpm. By turbocharging, the intake pressure is boosted twice as that for the naturally...
  44. K

    Calculating torque required to drive crank and slider

    Hi all The title pretty much says it all... The slider is required to push and pull a load of 70N. Radius between centre of crank axle and connecting rod is 12mm. I have been unable to find a formula to calculate torque required to enable selection of an appropriate motor to drive the...
  45. A

    Finding the maximum acceleration of a crank.

    Title: The title should actually read Finding the acceleration of a piston with respect to a cranks angle Homework Statement I have found a formula for calculating the acceleration of a piston, with respect to a cranks angle, however I've also found a couple of online calculators that give...
  46. M

    Position analysis of slider crank like mechanism using loop equations

    Hi Everyone, This is my first post so bare with me. Firstly, a bit of background about the problem. I am designing a near rear drive train for a formula student car which incorporates a chain tensioning device linking the differential to the rear of the chassis. Essentially I am wanting...
  47. A

    How to disconnect connecting rod and crank

    I have a mechanism wish to disconnect connecting rod and crank when i cycling so that i do nt need to use additional force to turn connecting rod also but connect them once my driving system is set up and piston that connected to rod can rotate my crank how can i set up this mechanism?
  48. C

    Why Does a VR Crank Sensor's Inductance Change with Different Casings?

    I helped my colleagues simulate inductance of vr crank sensor in Maxwell but my simulation result is quite different compared to the test one. Our sensor is quite simple, just a piece of permenant magnet, a piece of flux concentrator made of normal steel, and one copper coil hooked outside of...
  49. N

    Finding the acceleration of a variable crank mechanism.

    I've attempted multiple times, but don't really know which way to go and none of them are getting to the answer. I've got the question (below), got it wrong and been told the correct answer. A variable crank mechanism consists of a slider in a slot which is rotated around an axis at constant...
  50. B

    Static and dynamic analysis of a crank with pedal

    Hi. me and my friend have a problem that we can't really agree upon. we are doing an analysis study on a bike's crank and pedal. the first picture shows how we put the force of 210 N. picture 2 shows how we used "fixed geometry" to lock the part in place. now, this is the static...