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Overconstrained Mechanism
In mechanical engineering, an overconstrained mechanism is a linkage that has more degrees of freedom than is predicted by the mobility formula. The mobility formula evaluates the degree of freedom of a system of rigid bodies that results when constraints are imposed in the form of joints between the links. If the links of the system move in three-dimensional space, then the mobility formula is : M=6(N-1-j)+\sum_^j f_i, where is the number of links in the system, is the number of joints, and is the degree of freedom of the th joint. If the links in the system move planes parallel to a fixed plane, or in concentric spheres about a fixed point, then the mobility formula is : M=3(N-1-j)+\sum_^j f_i. If a system of links and joints has mobility or less, yet still moves, then it is called an ''overconstrained mechanism''. Reason of over-constraint The reason of over-constraint is the unique geometry of linkages in these mechanisms, which the mobility formula does not take i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ellipsograph01
A trammel of Archimedes is a mechanism that generates the shape of an ellipse. () It consists of two shuttles which are confined ("trammeled") to perpendicular channels or rails and a rod which is attached to the shuttles by pivots at fixed positions along the rod. As the shuttles move back and forth, each along its channel, all points on the rod move in elliptical paths. The motion of the rod is termed elliptical motion. The semi-axes ''a'' and ''b'' of the ellipses have lengths equal to the distances from the point on the rod to each of the two pivots. The straight lines described by the pivots are special cases of an ellipse, where the length of one axis is twice the distance between the pivots and that of the other is zero. All points on a circle with a diameter defined by the two pivots reciprocate in such straight lines. This circle corresponds to the smaller circle in a Tusi couple. The point midway between the pivots orbits in a circle around the point where the chann ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sarrus Linkage Anim 360x400
Sarrus is a surname. Notable people with the surname include: * Pierre-Auguste Sarrus (1813–1876), French musician and inventor ** Sarrusophone, a musical instrument * Pierre Frédéric Sarrus Pierre Frédéric Sarrus (; 10 March 1798, Saint-Affrique – 20 November 1861) was a French mathematician. Sarrus was a professor at the University of Strasbourg, France (1826–1856) and a member of the French Academy of Sciences in Paris (18 ... (1798–1861), French mathematician ** Sarrus linkage, a mechanical linkage {{surname ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trammel Of Archimedes
A trammel of Archimedes is a mechanism that generates the shape of an ellipse. () It consists of two shuttles which are confined ("trammeled") to perpendicular channels or rails and a rod which is attached to the shuttles by pivots at fixed positions along the rod. As the shuttles move back and forth, each along its channel, all points on the rod move in elliptical paths. The motion of the rod is termed elliptical motion. The semi-axes ''a'' and ''b'' of the ellipses have lengths equal to the distances from the point on the rod to each of the two pivots. The straight lines described by the pivots are special cases of an ellipse, where the length of one axis is twice the distance between the pivots and that of the other is zero. All points on a circle with a diameter defined by the two pivots reciprocate in such straight lines. This circle corresponds to the smaller circle in a Tusi couple. The point midway between the pivots orbits in a circle around the point where the chan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hoberman Mechanism
A Hoberman mechanism, or Hoberman linkage, is a deployable mechanism that turns linear motion into radial motion. The Hoberman mechanism is made of two angulated ridged bars connected at a central point by a revolute joint, making it move much like a scissor mechanism. Multiple of these linkages can be joined together at the ends of the angulated bars by more revolute joints, expanding radially to make circle shaped mechanisms. The mechanism is a GAE (generalize angulated element) where the coupler curve is a radial straight line. This allows the Hoberman mechanism to act with a single degree of freedom, meaning that it is an over-constrained mechanism because the mobility formula predicts that it would have a smaller degree of freedom than it does, as the mechanism has more degrees of freedom than the mobility formula predicts. The kinematic theory behind the Hoberman mechanism has been used to help further the understanding of mobility and foldability of deployable mechanisms. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crosshead
In mechanical engineering, a crosshead is a mechanical joint used as part of the slider-crank linkages of long reciprocating engines (either internal combustion or steam) and reciprocating compressors to eliminate sideways force on the piston. Also, the crosshead enables the connecting rod to freely move outside the cylinder. Because of the very small bore-to-stroke ratio on such engines, the connecting rod would hit the cylinder walls and block the engine from rotating if the piston was attached directly to the connecting rod like on trunk engines. Therefore, the longitudinal dimension of the crosshead must be matched to the stroke of the engine. Overview On smaller engines, the connecting rod links the piston and the crankshaft directly, but this transmits sideways forces to the piston, since the crankpin (and thus the direction the force is applied) moves from side to side with the rotary motion of the crank. These transverse forces are tolerable in a smaller engine. A large ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Revolute Joint
A revolute joint (also called pin joint or hinge joint) is a one- degree-of-freedom kinematic pair used frequently in mechanisms and machines. The joint constrains the motion of two bodies to pure rotation along a common axis. The joint does not allow translation, or sliding linear motion, a constraint not shown in the diagram. Almost all assemblies of multiple moving bodies include revolute joints in their designs. Revolute joints are used in numerous applications such as door hinges, mechanisms, and other uni-axial rotation devices. A revolute joint is usually made by a pin or knuckle joint, through a rotary bearing. It enforces a cylindrical contact area, which makes it a lower kinematic pair, also called a full joint. However, If there is any clearance between the pin and hole (as there must be for motion), so-called surface contact in the pin joint actually becomes line contact. The contact between the inner and outer cylindrical surfaces is usually assumed to be fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Engineering (magazine)
''Engineering'' is a monthly British magazine founded in 1865. It was initially published by the Office for Publication and Advertisements and reported on developments and news in many disciplines of engineering in Britain and abroad. It is now produced and published by Media Culture PLC and has the strapline "for innovators in technology, manufacturing and management". History The ''Engineering'' magazine was founded in 1866 by the American engineer and locomotive designer Zerah Colburn in London as a weekly rival to '' The Engineer''. It had the subtitle "an illustrated weekly journal". Colburn had used funds provided by Henry Bessemer, the English engineer and inventor known chiefly in connection with the Bessemer process for the manufacture of steel. ''Engineering'' was an instant success and soon overtook ''The Engineer'' as Colburn's writing style and wide engineering knowledge gave readers the information they needed. ''Engineering'' was initially published as an illust ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geoffrey Thomas Bennett
Geoffrey Thomas Bennett (1868–1943) was an English mathematician, professor at the University of Cambridge. Life and work Born in London, he began his secondary studies at the University College School, under Robert Tucker (mathematician), Robert Tucker. After one year at University College of London, Bennett obtained a scholarship at St. John's College, Cambridge, where he graduated in 1890 as Senior Wrangler (University of Cambridge), Senior Wrangler. However, the best grade in the Mathematical Tripos of that year was for Philippa Fawcett, but she was not included in the list for his gender. Upon completion of his studies he was appointed college lecturer of mathematics at Emmanuel College, Cambridge. He held a fellowship at the college from 1893 until his death in 1943. He had also great interest in music and athletics. He was a keen bicyclist and a good pianist. During the First World War he was member of the Anti-Aircraft Experimental Section (AAES) for his versatilit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bennett Four-bar Linkage
Bennett may refer to: People *Bennett (name), including a list of people with the surname and given name Places Canada * Bennett, Alberta *Bennett, British Columbia * Bennett Lake, in the British Columbia and Yukon Territory **Bennett Range **Bennett Lake Volcanic Complex United States *Bennett, Colorado *Bennett, Iowa *Bennett, Missouri *Bennett, North Carolina *Bennett, West Virginia * Bennett, Wisconsin, a town ** Bennett (community), Wisconsin, an unincorporated community *Bennett County, South Dakota * Bennett Mountain, in the Sonoma Mountains, California ** Bennett Valley * Bennett Township (other) Elsewhere *Bennett Island, in the East Siberian Sea * Bennett Islands, Antarctica Education *Bennett College, in Greensboro, North Carolina,U.S. *Bennett College (New York), U.S. * Bennett High School (other) * Bennett Middle School, Salisbury, Maryland, U.S. *Bennett Memorial Diocesan School, Tunbridge Wells, Kent, England * Bennett University, Greater Noida, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sarrus Linkage
The Sarrus linkage, invented in 1853 by Pierre Frédéric Sarrus, is a mechanical linkage to convert a limited circular motion to a linear motion or vice versa without reference guideways. It is a spatial six-bar linkage (6R) with two groups of three parallel adjacent joint-axes. Although Charles-Nicolas Peaucellier was widely recognized for being the first to invent such a straight-line mechanism, the Sarrus linkage had been invented earlier; however, it was largely unnoticed for a time. – Sarrus' mechanism Description The Sarrus linkage consists of four links in two identical groups that are perpendicular to each other, with all links having equal lengths. In the examples shown, the linkage uses two horizontal plates (cyan) ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steam Locomotive
A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material (usually coal, oil or, rarely, wood) to heat water in the locomotive's boiler to the point where it becomes gaseous and its volume increases 1,700 times. Functionally, it is a steam engine on wheels. In most locomotives, the steam is admitted alternately to each end of its cylinders, in which pistons are mechanically connected to the locomotive's main wheels. Fuel and water supplies are usually carried with the locomotive, either on the locomotive itself or in a tender coupled to it. Variations in this general design include electrically-powered boilers, turbines in place of pistons, and using steam generated externally. Steam locomotives were first developed in the United Kingdom during the early 19th century and used for railway transport until the middle of the 20th century. Richard Trevithick ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
