I am building a machine, and one of it's components is a mechanism that will convert rotational energy to a reciprocating horizontal movement.

I am aware of various mechanisms such as the Scotch Yoke shown below:

enter image description here

Which perform this translation. In fact, I would have used the Scotch yoke since it is mechanically simpler - however, the problem with the Scotch Yoke is that the extent of the lateral motion is constrained to the diameter of the wheel.

What I want is to be able to create a lateral reciprocating movement of extent NxD where N is a positive real number, and D is the diameter of the wheel.

Is there an existing mechanism that generates lateral displacements that are several times larger than the diameter of the rotating circle/wheel?


  • 1
    $\begingroup$ Use a lever with a long and short side. $\endgroup$
    – Solar Mike
    May 2, 2018 at 9:27
  • $\begingroup$ Whats wrong with slider and crank? $\endgroup$
    – joojaa
    May 2, 2018 at 14:07
  • $\begingroup$ What's wrong with a lead screw and nut or rack and pinion? $\endgroup$ May 2, 2018 at 17:13
  • 1
    $\begingroup$ A rack/pinion generates linear motion from rotational, but this is not the same as reciprocating. You’d need to be constantly switching the direction of the motor, which is not always feasible (e.g. if it were driven by a water-wheel or engine) $\endgroup$ May 4, 2018 at 8:46
  • $\begingroup$ Use a pulley system to amplify the lateral move. $\endgroup$
    – Karl H
    Dec 15, 2022 at 22:47

2 Answers 2


You may find Nguyen Duc Thang's '2100 animated mechanisms' useful. There is a .zip containing a useful PDF index of these - you are interested in 'Part 2', pages 57-114 http://wiki.dtonline.org/index.php/2100_Animated_Mechanical_Mechanisms

Two mechanisms I have picked out that you may find useful are: https://www.youtube.com/watch?v=56fJjeeEo38&feature=youtu.be and https://www.youtube.com/watch?v=ITYKygWmD9Q&feature=youtu.be

but without knowing the full design constraints of your problem, I can't comment further.

Slider-Crank Mechanism

  • $\begingroup$ Nice slider and crank that toggles between configuration. $\endgroup$
    – joojaa
    May 2, 2018 at 14:08
  • 1
    $\begingroup$ @JonathanRSwift sorry to sound gushing and all that - but can I just say that I love you and this site? :D This is exactly the sort of mechanism I had in mind, but couldn't quite articulate it. Also, thanks very much for linking to Nguyen Duc Thang's '2100 animated mechanisms'. I had watched a couple of his videos on YouTube, but couldn't remember his name! That's some might fine sperlunking! $\endgroup$ May 2, 2018 at 14:46
  • $\begingroup$ @JonathanRSwift I notice that the speed of the slider is not constant (it appears to slide back faster than when sliding forward). Is it the animation that makes it look like that, or is that the actual behavior of the slider? - if the latter is it possible for the mechanism to be tweaked so that both forward and backward motion is the same speed (this is important as the linear motion of this mechanism will be fed into another mechanism. Cheers $\endgroup$ May 2, 2018 at 14:58
  • $\begingroup$ @HomunculusReticulli - No problem - I appreciate the thanks! It's not the animation, both the videos I linked above have non-equal speeds in each direction. Can you explain a little more about the application so I/others can possibly help with a more appropriate mechanism? Does it need to have the same speed in both directions? take the same amount of time? Does it need to be sinusoidal (as with the Scotch Yoke), or will something else do? $\endgroup$ May 2, 2018 at 17:06

For those viewing this thread four+ years after it was originally posted, Jay Gould has an excellent series of videos on circular to linear motion. He shows many variations on the Scotch Yoke and the subtleties of their differences. The first video link is here https://www.youtube.com/watch?v=QZ2XFTblrC8


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