Crank

Thu, 30 Sep 2010

The crank is used to convert rotary motion to reciprocating or oscillating motion. With careful timing it can also be used to convert motion the other way… from reciprocating to rotary.

The throw of the reciprocating motion is determined by the offset of the crank

USEFUL LINK:
Make your own working crank mechanism. Download and make this model and find out about cranks first hand. More info…

Comments (34)

  • Anonymous October 11, 2010 at 5:37 pm

    what ?

    im doing this in tech in school its really hard

    • robives October 11, 2010 at 7:05 pm

      Questions?

      Anything you want to know? I might be able to help. 

      Rob

      • Anonymous November 2, 2010 at 6:47 pm

        hi rob, do you know what type

        hi rob, do you know what type of movement this mechanism moves in please???? x

        • robives November 2, 2010 at 8:27 pm

          I’m presuming you are talking

          I'm presuming you are talking about the photo sent on by DCJ ? I'm not sure but it looks like it might be a crank slider. Wire crank in the box, wire push rod from the crank, up through a hole in the box top connected to the dancer. Is that right DCJ?

          • DCJ February 4, 2011 at 2:54 am

            Yes, the mechanism is a

            Yes, the mechanism is a crank, the wire pass thru a restricted hole that makes the legs move in a circular movement. The motion of the legs is quick in its lateral movement giving the 'shuffler / jerking' effect to the dance.

            On an aside note, the school subscription sounds like a great idea.

    • Anonymous October 19, 2010 at 7:33 pm

      Aha, so are we. It’s so

      Aha, so are we. It's so hard!

      I don't understand most of it 😛

  • DCJ October 21, 2010 at 3:03 am

    Hello Rob
    I am a Technology

    Hello Rob

    I am a Technology teacher in New Zealand who teaches a Automata unit to yr 9 students (13-14 yrs old). I have found your resources to be fantastic in helping the students to understand mechanisms. The photo is a Automaton by one of my students, it is a 'Shuffler' ('shuffle' is a type of dance) and it uses a crank and lever mechanism.


    • robives October 21, 2010 at 1:06 pm

      Fantastic! Thanks for sending

      Fantastic! Thanks for sending in the picture, that shuffler looks great.

  • Anonymous November 3, 2010 at 12:01 pm

    Hey just wanted to say

    Hey just wanted to say thankyou very much for this extremely usefull Website, im using it to help me gain a good understanding of that different type of mechanisms that i could feature in the product that im designing. this site has really helped me with my tech coursework, keep up the good work !!

    • robives November 3, 2010 at 7:01 pm

      Thanks! Glad to be of service

      Thanks! Glad to be of service 🙂

      • Anonymous November 6, 2010 at 12:16 pm

        hi rob im making a golf ball

        hi rob im making a golf ball dispenser and i was wondering if u knew wat type of mechanism i could use so that one ball comes out at a time?

  • Anonymous November 26, 2010 at 5:05 pm

    Hi there! I would just like

    Hi there! I would just like to ask, is crank a suitable mechanism on a model that has a train track with a train going from left to right and vice versa?

    • robives November 26, 2010 at 11:00 pm

      You could use a crank to make

      You could use a crank to make a train go back and forth but the motion would be limited to the length of throw of the crank.  A pulley or belt drive might be a better solution

  • yasminh February 7, 2011 at 8:22 am

    Hi Rob,
    I need to design a

    Hi Rob,

    I need to design a mechanism that convert reciprocating motion to rotary motion. I have several ideas for

    the other way, but this conversion is a little difficult.

    It says above, that With careful timing the crank can be used to convert that kind of motion.

    What does it mean? How can I do that? if the motion is coming from the left, the wheel is not doing a

    complete round.

    thanks!

    • robives February 7, 2011 at 4:26 pm

      @yasminh This is basically

      @yasminh This is basically what a piston does. You are correct that the motion is not powered all the way round. Push the piston and the wheel will rotate half way round, the piston then relies on the momentum of the rotating wheel to keep it moving back to the start position.

      • Anonymous May 17, 2011 at 10:08 am

        Hey robives, your website is

        Hey robives, your website is great, it is so simple and cuts out all the bull.

        Have you considered making an electronics site ?

  • Anonymous May 22, 2011 at 4:39 pm

    What kind of mechanism would

    What kind of mechanism would I need for a flying pig?

    • robives May 23, 2011 at 5:54 am

      The Flying Pig uses a crank

      The Flying Pig uses a crank slider mechanism.

      • Anonymous June 23, 2011 at 2:20 am

        rotary motion transfered to

        rotary motion transfered to reciprocating motion as I understand it.

        • Anonymous October 19, 2011 at 7:26 pm

          i don’t get this

          i don't get this

          • Anonymous November 23, 2011 at 2:26 am

            Gah! I thought I already

            Gah! I thought I already found what I was looking for in the quick return mechanism but this crank animation is very similar. In the animation above where the movement is converted to swinging an arc, is the left-right to right-left movement swinging at the same rate? or is one slower than the other?

      • Anonymous June 10, 2012 at 2:13 pm

        Rob could you tell me some

        Rob could you tell me some examples, in which a crank is used in.

        Bicycle pedal, petrol and steam engines, mechanical hacksaw, windscreen wipers… – RI

  • Anonymous November 23, 2011 at 2:31 am

    Between this and the quick

    Between this and the quick return mechanism…(using the animation above) is the left-right to right-left motion moving at the same rate?

  • Anonymous January 18, 2012 at 7:06 pm

    heya im stuck on drawing a

    heya im stuck on drawing a diagram for my flying horse im using the crank any clues?

    You might be better with a crank slider – RI

  • LM January 21, 2012 at 5:54 pm

    Rob, I am doing a school

    Rob, I am doing a school project on mechanisms, but I can't think or find any examples of a product (object/item) which uses this mechanism. Can you help me?

    LM

    P.S. This website is so cool and has been a great help!

    How about a mechanical hacksaw or windscreen wiper blades?- RI

    • LM January 22, 2012 at 3:42 pm

      Thank you so much! 
      LM

      Thank you so much! 

      LM

      • Anonymous May 29, 2012 at 7:04 pm

        Is there a crank on a bike

        Is there a crank on a bike and where is it and what is its function 

        Thanks 🙂

        The crank on the bike is the pedal. It is used to convert downward force from the leg into rotary motion in the wheels – RI

  • Anonymous September 27, 2012 at 11:50 am

    Hi Rob i just want to say

    Hi Rob i just want to say that you are a amazing person with great taste in mechanisms and clothing.

    P.S i like your glasses

    P.S.S what are cranks used in 

    yours sincerly joseph

  • Anonymous November 3, 2012 at 12:41 pm

    thank you for this great

    thank you for this great site. i am 12 years old and doing automata in D.T. and this perfect for me, and i highly recommend this site to any one doing automata.

  • Anonymous January 27, 2013 at 2:30 pm

    Hi Rob I need to convert

    Hi Rob I need to convert circular motion to vertical straight up and down movement, how do I do this?

    Try using a crank mechanism like the video clip at the top of the page, turn it through 90 degrees and the piston would move up and down rather than side to side. – RI

  • Anonymous October 6, 2013 at 2:57 pm

    Hello,
    I want to use this

    Hello,

    I want to use this pattern to move a sculpture ( that weights about 300gr) and has a 40 cm rod, how big does the connecting rod needs to be ? How can I calculate this?

     

    Thank you

    Kleoni

    What range of movement do you want? – RI

  • Anonymous October 19, 2013 at 6:05 pm

    what is the throw and

    what is the throw and offset

    The throw is the total distance moved back and forth, the offset is half that. – RI

  • kieron2k June 24, 2014 at 1:00 pm

    Why dont people create an

    Why dont people create an account it saves robbie having to approve requests every two minutes go on give it a go and sign up

     

    Thanks A Bunch

    Kezza

    • Anonymous November 12, 2014 at 5:17 am

      I am trying to convert the

      I am trying to convert the oscillating movement of the crank to rotary movement, and it seems impossible. Any suggestions?

      Yes, you’ll need a flywheel. A heavy wheel that will keep turning when the crank is at the extremes of its movement. – RI

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