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Ball-bearing
A ball bearing is a type of rolling-element bearing that uses ball (bearing), balls to maintain the separation between the bearing (mechanical), bearing race (bearing), races. The purpose of a ball bearing is to reduce rotational friction and support radius, radial and axis of rotation, 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 Wheel hub assembly, 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 structural load, 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 o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bearing (mechanical)
A bearing is a machine element that constrains relative motion to only the desired motion, and reduces friction between moving parts. The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or, it may ''prevent'' a motion by controlling the vectors of normal forces that bear on the moving parts. Most bearings facilitate the desired motion by minimizing friction. Bearings are classified broadly according to the type of operation, the motions allowed, or to the directions of the loads (forces) applied to the parts. Rotary bearings hold rotating components such as shafts or axles within mechanical systems, and transfer axial and radial loads from the source of the load to the structure supporting it. The simplest form of bearing, the ''plain bearing'', consists of a shaft rotating in a hole. Lubrication is used to reduce friction. In the ''ball bearing'' and ''roller bearing'', to reduce sliding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spherical Roller Bearing
A spherical roller bearing is a rolling-element bearing that permits rotation with low friction, and permits angular misalignment. Typically these bearings support a rotating shaft in the bore of the inner ring that may be misaligned in respect to the outer ring. The misalignment is possible due to the spherical internal shape of the outer ring and spherical rollers. Despite what their name may imply, spherical roller bearings are not truly spherical in shape. The rolling elements of spherical roller bearings are mainly cylindrical in shape, but have a (barrel like) profile that makes them appear like cylinders that have been slightly over-inflated (i.e. like a barrel). Construction Spherical roller bearings consist of an inner ring with two raceways inclined at an angle to the bearing axis, an outer ring with a common spherical raceway, spherical rollers, cages and, in certain designs, also internal guide rings or center rings. These bearings can also be sealed. History The sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rolling-element Bearing
In mechanical engineering, a rolling-element bearing, also known as a rolling bearing, is a bearing which carries a load by placing rolling elements (such as balls or rollers) between two concentric, grooved rings called races. The relative motion of the races causes the rolling elements to roll with very little rolling resistance and with little sliding. One of the earliest and best-known rolling-element bearings are sets of logs laid on the ground with a large stone block on top. As the stone is pulled, the logs roll along the ground with little sliding friction. As each log comes out the back, it is moved to the front where the block then rolls on to it. It is possible to imitate such a bearing by placing several pens or pencils on a table and placing an item on top of them. See " bearings" for more on the historical development of bearings. A rolling element rotary bearing uses a shaft in a much larger hole, and cylinders called "rollers" tightly fill the space between t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Self-aligning 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. History Although bearings had been developed since ancient times, the first mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Moore (cyclist)
James Moore (14 January 1849 – 17 July 1935) was an English bicycle racer. He is popularly regarded as the winner of the first official cycle race in the world in 1868 at St-Cloud, Paris, although this claim seems to be erroneous. In 1869 he won the world's first road race Paris–Rouen sponsored by ''Le Vélocipède Illustré'' and the Olivier brothers' Michaux Bicycle Company. Moore covered the in 10 hours and 25 minutes. He was one of the first stars of cycle racing, dominating competition for many years. Early life and education Moore was born in Long Brackland, Bury St Edmunds, Suffolk, England on 14 January 1849. Moore's father, also James, was a blacksmith and farrier. His mother was Elizabeth Ann Moore. The couple had two sons and five daughters.Wadley, J.B. (1969), ''International Cycle Sport'' (UK) pp17-19 The sons, Alfred and James, were born in Britain, the daughters in France. The family moved to Paris when James was four years old. The reason for the move i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sven Gustaf Wingqvist
Sven Gustaf Wingqvist (10 December 1876 – 17 April 1953) was a Swedish engineer, inventor and industrialist, and one of the founders of Svenska Kullagerfabriken (SKF), one of the world's leading ball bearing and roller bearing makers. Sven Wingqvist invented the multi-row self-aligning ball bearing in 1907. Chronology *1876: Born December 10 in Kumla Municipality south of Örebro, Sweden. His parents are railway station inspector at Hallsberg S. D. Wingqvist and Anna Lundberg. *1894: Graduated from Rudbecksskolan in Örebro (Örebro Technical Elementary School). *1899: Wingqvist became employed as an operating engineer at Gamlestadens Textile Industry in Göteborg. He worked here for many years to find a solution to the problems with frequent break downs in the ball bearings for the main drive shafts. This was caused by the ground conditions, as the factory was built on clay. The shaft bearing supports moved some fractions of millimeters from time to time, hardly measurable ... [...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 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, coastal nav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Harrison
John Harrison ( – 24 March 1776) was a self-educated English Carpentry, carpenter and clockmaker who invented the marine chronometer, a long-sought-after device for solving the History of longitude, problem of calculating longitude while at sea. Harrison's solution revolutionized navigation and greatly increased the safety of long-distance sea travel. The problem he solved was considered so important following the Scilly naval disaster of 1707 that the Parliament of Great Britain, British Parliament offered financial rewards of up to £20,000 (equivalent to £ in ) under the 1714 Longitude Act. In 1730, Harrison presented his first design, 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. Toward the end of his life, he received recognition and a reward from Parliament. Harri ... [...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 portrayed World War II ace Pappy Boyington in the television series '' Baa Baa Black Sheep'' (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.''The PM Show with Robert Conrad'' crntalk.com; accessed January 11, 2016. Early life Conrad was born Conrad Robert Fa ...[...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 cells divide in organisms, asymmetry in organisms is fairly usual in at least one dimension, with biological symmetry also being common in at least one dimension. Louis Pasteur proposed that biological molecules are asymmetric because the cosmic .e. physicalforces 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 Asymmetry is an important and widespread ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicon Nitride
Silicon nitride is a chemical compound of the elements silicon and nitrogen. 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 silicon nitride phases (with chemical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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