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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

(in Russian, sharnirnyi mekhanizm), a mechanism whose elements (links) form only rotating kinematic pairs (linkages).

Figure 1. Spherical four-bar motion: (0) fixed link, (1), (2), and (3) movable links

Depending on the method used to define the required motion of a working link, linkworks are subdivided into positioning, guiding, and transmission mechanisms and mechanisms for interrupted motion. Positioning linkworks are designed to move a working link from one position to another; the number of defined positions is usually two, less often three or four. Such linkworks are used in metallurgical machines (such as tilters, tippers, and mechanisms for plugging tap holes) and in automatic machinery for the food-processing industry (for positioning working members of machines). Guiding linkworks are designed to move along a specified curve a single point of a link that does not form a kinematic pair with the stay. Linkworks that guide along the arc of a circle (circular guiding mechanisms) and straight-line mechanisms, such as the Chebyshev parallel motion, are the most widely used types. Linkworks are also used to shape parabolas and hyperbolas, such as the mechanisms for grinding the mirrors

Figure 2. Linkwork for interrupted motion

of astronomical instruments. Transmission linkworks are designed to convert rotary motions according to a specific law. They act as mechanisms for reproducing a given function. In calculators, transmission linkworks are used to perform such mathematical operations as addition, multiplication, and raising to powers. Through special selection of the lengths of the links, it is possible to obtain an approximate reproduction of diverse functions. For example, when the function y = f (x) is reproduced, the angles of rotation of one rotating link are proportional to the argument x, and the angles of rotation of the other are proportional to the function y.