|
Ball Bearing
A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this by using at least two races to contain the balls and transmit the loads through the balls. In most applications, one race is stationary and the other is attached to the rotating assembly (e.g., a hub or shaft). As one of the bearing races rotates it causes the balls to rotate as well. Because the balls are rolling, they have a much lower coefficient of friction than if two flat surfaces were sliding against each other. Ball bearings tend to have lower load capacity for their size than other kinds of rolling-element bearings due to the smaller contact area between the balls and races. However, they can tolerate some misalignment of the inner and outer races. Common ball bearing designs include ''angular contact, axial, deep-groove,'' an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paris–Rouen (cycle Race)
Paris–Rouen was the first cycle race covering a distance between two cities. It was held between the cities of Paris and Rouen on 7 November 1869. The winner of the inaugural race was an Englishman living in Paris, James Moore, who rode the 123 kilometres dividing both cities in 10 hours and 40 minutes, including time spent walking his bicycle up the steeper hills. The event was organized by the fortnightly cycling magazine Le Vélocipède Illustré and the Olivier brothers, owners of a bicycle manufacturer company called ''The Michaux Company''. They were delighted with the success of short races held in Parc de Saint Cloud, Paris and on 7 November they promoted a race between Paris and Rouen, covering a distance of 123 kilometres. The first prize was one thousand gold francs and a bicycle. The rules of the race said that the riders were not ''to be pulled by a dog or use sails''.Woodland, L. (2005), ''This Island Race'', Mousehold Press, p. 5 A total of 120 riders, inclu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Longitude (book)
''Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time'' is a 1995 best-selling book by Dava Sobel about John Harrison, an 18th-century clockmaker who created the first clock ( chronometer) sufficiently accurate to be used to determine longitude at sea—an important development in navigation. The book was made into a television series entitled ''Longitude''. In 1998, ''The Illustrated Longitude'' was published, supplementing the earlier text with 180 images of characters, events, instruments, maps and publications. Problem of longitude Determining longitude on land was fairly easy compared to the task at sea. A stable surface to work from, known coordinates to refer to, a sheltered environment for the unstable chronometers of the day, and the ability to repeat determinations over time made for great accuracy. For calculating longitude at sea however, early ocean navigators had to rely on dead reckoning, or if in sight of land, coasta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Harrison
John Harrison ( – 24 March 1776) was an English carpenter and clockmaker who invented the marine chronometer, a long-sought-after device for solving the History of longitude, problem of how to calculate longitude while at sea. Harrison's solution revolutionized navigation and greatly increased the safety of long-distance sea travel. The problem he solved had been considered so important following the Scilly naval disaster of 1707 that the Parliament of Great Britain, British Parliament was offering financial rewards of up to £20,000 (equivalent to £ in ) under the 1714 Longitude Act, though Harrison never received the full reward due to political rivalries. He presented his first design in 1730, and worked over many years on improved designs, making several advances in time-keeping technology, finally turning to what were called sea watches. Harrison gained support from the Board of Longitude, Longitude Board in building and testing his designs. Towards the end of his life, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wire Race Bearing
A wire race bearing is a rolling-element bearing, where the balls or rollers run on race (bearing), races resembling loops of wire. Roller bearings may use just two races, but ball bearings typically use three or four races. Wire race bearings can be large yet lightweight and with small profile and good precision. Wire races have little intrinsic structure and must be adequately supported by the bearing housing. Balls, rollers or even cross rollers are used as rolling elements. Due to the design wire race bearings are commonly called '4-point-contact' bearings.Decker/Kabus, Maschinenelemente, Funktion, Gestaltung und Berechnung, Page 422, Hanser, 15th Issue 2000, The first wire race bearing was invented in 1934 by Erich Franke, co-founder of Franke & Heydrich KG in Aalen, Germany (nowadays Franke GmbH). As a young design engineer of Carl Zeiss AG, Carl-Zeiss-Werke in Jena, Franke intended to design a very space-saving bearing for an optical device. The aim of his thoughts was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert Conrad (inventor)
Robert Conrad (born Conrad Robert Falk; March 1, 1935 – February 8, 2020) was an American film and television actor, singer, and stuntman. He is best known for his role in the 1965–1969 television series ''The Wild Wild West'', playing the sophisticated Secret Service agent James T. West. He also portrayed private investigator Tom Lopaka in ''Hawaiian Eye'' (1959–1963) and World War II ace Pappy Boyington in ''Baa Baa Black Sheep'' (1976–1978; later syndicated as ''Black Sheep Squadron''). In addition to acting, he was a singer and recorded several pop/rock songs in the late 1950s and early 1960s as Bob Conrad. He hosted a weekly two-hour national radio show (''The PM Show with Robert Conrad'') on CRN Digital Talk Radio beginning in 2008. Early life Conrad was born Conrad Robert Falk in Chicago. His father, Leonard Henry Falk, was 17 years old at the time of Conrad's birth and was of German descent. His mother, Alice Jacqueline Hartman (daughter of Conrad and H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ball Bearing Self Aligning
A ball is a round object (usually spherical, but sometimes ovoid) with several uses. It is used in ball games, where the play of the game follows the state of the ball as it is hit, kicked or thrown by players. Balls can also be used for simpler activities, such as catch or juggling. Balls made from hard-wearing materials are used in engineering applications to provide very low friction bearings, known as ball bearings. Black-powder weapons use stone and metal balls as projectiles. Although many types of balls are today made from rubber, this form was unknown outside the Americas until after the voyages of Columbus. The Spanish were the first Europeans to see the bouncing rubber balls (although solid and not inflated) which were employed most notably in the Mesoamerican ballgame. Balls used in various sports in other parts of the world prior to Columbus were made from other materials such as animal bladders or skins, stuffed with various materials. As balls are one of the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Run-out
Run-out or runout is an inaccuracy of rotating mechanical systems, specifically that the tool or shaft does not rotate exactly in line with the main axis. For example; when drilling, run-out will result in a larger hole than the drill's nominal diameter due to the drill being rotated eccentrically (off axis instead of in line). In the case of bearings, run-out will cause vibration of the machine and increased loads on the bearings. Run-out is dynamic and cannot be compensated. If a rotating component, such as a drill chuck, does not hold the drill centrally, then as it rotates the rotating drill will turn about a secondary axis. Absolute alignment is impossible; a degree of error will always be present. Types Run-out has two main forms: * ''Radial run-out'' is caused by the tool being translated off the machine axis, still parallel. Radial run-out will measure the same all along the machine axis. * '' Axial run-out'' is caused by the tool or component being at an a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asymmetry
Asymmetry is the absence of, or a violation of, symmetry (the property of an object being invariant to a transformation, such as reflection). Symmetry is an important property of both physical and abstract systems and it may be displayed in precise terms or in more aesthetic terms. The absence of or violation of symmetry that are either expected or desired can have important consequences for a system. In organisms Due to how cell (biology), cells divide in organisms, asymmetry in organisms is fairly usual in at least one dimension, with Symmetry in biology, biological symmetry also being common in at least one dimension. Louis Pasteur proposed that biological molecules are asymmetric because the cosmic [i.e. physical] forces that preside over their formation are themselves asymmetric. While at his time, and even now, the symmetry of physical processes are highlighted, it is known that there are fundamental physical asymmetries, starting with time. Asymmetry in biology Asy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicon Nitride
Silicon nitride is a chemical compound of the elements silicon and nitrogen. (''Trisilicon tetranitride'') is the most thermodynamically stable and commercially important of the silicon nitrides, and the term ″''Silicon nitride''″ commonly refers to this specific composition. It is a white, high-melting-point solid that is relatively chemically inert, being attacked by dilute HF and hot . It is very hard (8.5 on the mohs scale). It has a high thermal stability with strong optical nonlinearities for all-optical applications. Production Silicon nitride is prepared by heating powdered silicon between 1300 °C and 1400 °C in a nitrogen atmosphere: :3 Si + 2 → The silicon sample weight increases progressively due to the chemical combination of silicon and nitrogen. Without an iron catalyst, the reaction is complete after several hours (~7), when no further weight increase due to nitrogen absorption (per gram of silicon) is detected. In addition to , several other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ceramic
A ceramic is any of the various hard, brittle, heat-resistant, and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain, and brick. The earliest ceramics made by humans were fired clay bricks used for building house walls and other structures. Other pottery objects such as pots, vessels, vases and figurines were made from clay, either by itself or mixed with other materials like silica, hardened by sintering in fire. Later, ceramics were glazed and fired to create smooth, colored surfaces, decreasing porosity through the use of glassy, amorphous ceramic coatings on top of the crystalline ceramic substrates. Ceramics now include domestic, industrial, and building products, as well as a wide range of materials developed for use in advanced ceramic engineering, such as semiconductors. The word '' ceramic'' comes from the Ancient Greek word (), meaning ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
