Model: N01 Ratchet and Pawl Mechanism
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Model Metadata
Ratchet Mechanisms
Title (English):
Ratchet and Pawl Mechanism
Title (German):
Zahngesperre mit zwei šusseren und einer inneren Sperrung
Franz Reuleaux
Date Created:
Gustav Voigt Werkstatt
Base: Width x Depth [198,89]mm; Overall: W x D x Height [221,124,236]mm
cast iron and brass on wood pedestal
For educational use only. All rights reserved by the contributor(s) and publisher(s).
General public
The ratchet and pawl mechanism allows motion in one direction but locks it in the other direction. In this sense it acts in the same way as a diode in an electrical circuit or a check value in a water pipe. The ratchet and pawl was often used with a winch or windlass, a horizontal drum with a rope or cable attached, which allowed the rope to be wound onto the cylinder but prevented the cylinder from unwinding the rope. Reuleaux was fascinated with ratchet mechanisms and designed several different models to illustrate the different motions and uses of the ratchet. In his machine design book The Constructor (1893), he defined the ratchet in the similar way as Leonardo da Vinci; "The object of the ratchet is to check the action of certain portions of a machine and so modify an otherwise continuous motion into some intermittent form." (Page 150). The use of control valves in steam engines and internal combustion engines in the 19th century to regulate speed represented the beginnings of automatic control of machines. Reuleaux recognized the importance of control but did not have the mathematical concepts to describe it. He saw instead the special digital nature of ratchet mechanisms, on or off, as having special significance in machine regulation and created several models to express the role of ratchets in machine control devices. This model can be printed out using a rapid prototyping machine. The stereolithography file (STL) to print Model N-1 can be downloaded from KMODDL.
Descr Author:
Francis Moon
Descr Date:
Image Metadata
N01. Ratchet and Pawl Mechanism
Jon Reis/ Jon Reis Photography grants Cornell University Libraries, and the Cornell College of Engineering the rights to display copyrighted images of the Reuleaux Collection of Kinematic Mechanisms on the Cornell University and National Science Digital Library web sites and for unlimited use in Cornell University Library publications for education purposes only. Rights for all other uses such as editorial, advertising, web use and display by third parties not affiliated with Cornell University are reserved by the photographer.
Date Created:
2005-01-19 11:02:16
Size (w x h):
256 x 384

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