Positive Return Mechanism with Curved Triangle
- Title:
- Positive Return Mechanism with Curved Triangle
- Title (German):
- Gleichseitiges Bogendreieck in grader Schleife mit Polbahn
- Collection:
- Reuleaux Kinematic Mechanisms Collection
- Set:
- L. Positive Return Constant Breadth Cams
- Designer:
- Reuleaux, F. (Franz), 1829-1905
- Manufacturer:
- Gustav Voigt Werkstatt
- Date:
- 1882
- Country:
- Germany
- Voigt Catalog Model:
- L1
- File Name:
- L01.jpg
- Work Type:
- Mechanical model
- Materials/Techniques:
- cast iron and brass on wood pedestal
- Subject:
- constant width, constant breadth, Reuleaux triangle
Kinematics of Machinery - Measurement:
- 199 x 88 (millimeters, width x depth)
273 x 118 x 202 (millimeters, width x depth x height) - Description:
- In this mechanism, rotary motion of a crank (in the back) turns the equilateral curved triangle. The curved triangle is a figure of constant width and its motion causes the slider to oscillate back and forth through contact with two parallel guides. At either the left or right extremes of this motion there is a period of finite dwell or rest of the slider. Such a mechanism is called in modern texts on mechanisms a positive return cam—i.e. the curved triangle is the cam and it acts to move the slider in both directions. The pure version of the curved triangle in parallel guides is also represented in the Reuleaux-Voigt models B-2, B-3, B-4. The curved triangle cam was used in early 19th century steam engines to activate a control value as in a Woolf engine. It was noted in a number of early kinematics books such as Willis (1841,1870). One reference cites Euler as one who studied its geometric properties. In modern mathematical texts the constant width curved triangle has been called the Reuleaux triangle—not because he invented it—but because Reuleaux was the first to generalize the curved triangle to other curves of constant width. This model also contains the centrodes of the cam-slider engraved on a glass slide. In a beautiful demonstration of the idea that all planar motions can be represented by pure rolling, Reuleaux’s model shows that the motion is equivalent to rolling of a duangle on a curved triangle (i.e. the centrodes). [Francis Moon 2001-00-00]
The 220 models in Cornell University’s Reuleaux Collection were built in the late 19th century to demonstrate the elements of machine motion, as theorized by the German engineer Franz Reuleaux. The University acquired the models in 1882 for use in teaching and research. The Reuleaux models are classified according to the alphanumeric schema employed in the catalog of the manufacturer, Gustav Voigt. The letter in a model's ID (e.g., B14 or S35) refers to a class of mechanism; the number is a specific instance of the class. This classification scheme is a simplified version of the taxonomy of machine elements elaborated in Reuleaux's work. - Repository:
- Sibley School of Mechanical and Aerospace Engineering, Cornell University
- Format:
- Image
- Rights:
- Photography credit: Jon Reis (www.jonreis.com). Jon Reis Photography grants Cornell University Libraries and the Cornell College of Engineering the rights to display copyrighted images of the Reuleux collection of kinetic machines 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, including but not limited to, editorial, commercial, advertising, web use and display by third parties not affiliated with Cornell University are reserved by the photographer. The written permission of any copyright and other rights holders is required for distribution, reproduction, or other use that extends beyond what is authorized by fair use and other statutory exemptions. Responsibility for making an independent legal assessment of an item and securing any necessary permissions ultimately rests with persons desiring to use the item. For questions about this item or other items please contact the Physical Sciences Librarians at pslref@cornell.edu.