Rhombus Straight-Line Linkage

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This straight-line model contains seven bar type links and one slider link counting the grounded link. Four of these links form a rhombus figure. There are also six revolute joints, three of which are double joints connecting three bodies instead of two bodies. Without the slider link this rhombus linkage would have two degrees of freedom but the slider link removes one producing an exact straight-line motion of the lower pin joint. This linkage is related to a class of mechanisms called inversors (See tutorial in straight-line mechanisms and the Peaucillier-Lipkin linkage , S-35). Mathematicians such as Chebyshev and Sylvester in the 19th century devoted a great deal of study to the class of straight-line mechanisms.