Scotch yoke
The Scotch yoke (also known as slotted link mechanism
Applications
This setup is most commonly used in control
Although not a common metalworking machine nowadays, crude shapers can use Scotch yokes. Almost all those use a Whitworth linkage, which gives a slow speed forward cutting stroke and a faster return.
It has been used in various internal combustion engines, such as the Bourke engine, SyTech engine, and many hot air engines and steam engines.
The term scotch yoke continues to be used when the slot in the yoke is shorter than the diameter of the circle made by the
What is essentially a Scotch yoke is used in the Tide-Predicting Machine No. 2 to generate a sinusoidal motion (sine functions).
Internal combustion engine uses
Under ideal engineering conditions, force is applied directly in the line of travel of the assembly. The sinusoidal motion, cosinusoidal velocity, and sinusoidal acceleration (assuming constant angular velocity) result in smoother operation. The higher percentage of time spent at
The Scotch yoke is not used in most internal combustion engines because of the rapid wear of the slot in the yoke caused by sliding friction and high contact pressures[
Modifications
An improved Scotch yoke, with a means of absorbing sideways thrust, was patented in 1978 by William L. Carlson, Jr., U.S. patent 4,075,898.[8]
References
- ^ "ME 700 Mechanisms | EdLabQuip".
- ^ General Construction, Baldwin Gasoline Industrial Locomotives Baldwin Locomotive Works Record, No. 74, 1913; pages 7-9. The use of the scotch yoke is explained page 8.
- ^ Norman W. Storer, Electric Locomotive, U.S. patent 991,038, granted May 2, 1911. The use of the scotch yoke is discussed on page 2 of the text.
- ^ a b c "Science Links Japan | Effect of Piston Speed around Top Dead Centre on Thermal Efficiency". Sciencelinks.jp. 2009-03-18. Archived from the original on 2012-01-27. Retrieved 2011-12-06.
- ^ Bourke Engine Documentary, Published 1968, p50, "Appraising Engine Efficiency" para2
- ^ Bourke Engine Documentary, Published 1968, p51, "Important Factors in Engine Design"
- ^ "Effect of the Ratio Between Connecting-rod Length and Crank Radius on Thermal Efficiency". Science Links Japan. Archived from the original on 2008-01-28. Retrieved 2008-07-08.
- ^ "Patent US4075898 - Scotch yoke - Google Patents". Retrieved 2013-01-21.
External links
- Brock Institute for Advanced Studies: Scotch Yoke
- "Comparing Simple Crank/Slider and Scotch Yoke Mechanisms" by Fred Klingener, The Wolfram Demonstrations Project; Active demo.