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Planetary Gearbox
An epicyclic gear train (also known as a planetary gearset) is a gear reduction assembly consisting of two gears mounted so that the center of one gear (the "planet") revolves around the center of the other (the "sun"). A carrier connects the centers of the two gears and rotates, to carry the planet gear(s) around the sun gear. The planet and sun gears mesh so that their pitch circles roll without slip. If the sun gear is held fixed, then a point on the pitch circle of the planet gear traces an epicycloid curve. An epicyclic gear train can be assembled so the planet gear rolls on the inside of the pitch circle of an outer gear ring, or ring gear, sometimes called an ''annulus gear''. Such an assembly of a planet engaging both a sun gear and a ring gear is called a planetary gear train.J. J. Uicker, G. R. Pennock and J. E. Shigley, 2003, ''Theory of Machines and Mechanisms,'' Oxford University Press, New York.B. Paul, 1979, ''Kinematics and Dynamics of Planar Machinery'', Prent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epicyclic Gearing Stationary Ring
An epicyclic gear train (also known as a planetary gearset) is a Reduction drive, gear reduction assembly consisting of two gears mounted so that the center of one gear (the "planet") revolves around the center of the other (the "sun"). A carrier connects the centers of the two gears and rotates, to carry the planet gear(s) around the sun gear. The planet and sun gears mesh so that their pitch circles roll without slip. If the sun gear is held fixed, then a point on the pitch circle of the planet gear traces an epicycloid curve. An epicyclic gear train can be assembled so the planet gear rolls on the inside of the pitch circle of an outer gear ring, or ring gear, sometimes called an ''annulus gear''. Such an assembly of a planet engaging both a sun gear and a ring gear is called a planetary gear train.J. J. Uicker, G. R. Pennock and J. E. Shigley, 2003, ''Theory of Machines and Mechanisms,'' Oxford University Press, New York.B. Paul, 1979, ''Kinematics and Dynamics of Planar Mac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antikythera Mechanism
The Antikythera mechanism ( , ) is an Ancient Greece, Ancient Greek hand-powered orrery (model of the Solar System). It is the oldest known example of an Analog computer, analogue computer. It could be used to predict astronomy, astronomical positions and eclipses decades in advance. It could also be used to track the four-year cycle of athletic games similar to an Olympiad, the cycle of the ancient Olympic Games. The artefact was among wreckage retrieved from Antikythera wreck, a shipwreck off the coast of the Greek island Antikythera in 1901. In 1902, during a visit to the National Archaeological Museum, Athens, National Archaeological Museum in Athens, it was noticed by Greek politician Spyridon Stais as containing a gear, prompting the first study of the fragment by his cousin, Valerios Stais, the museum director. The device, housed in the remains of a wooden-framed case of (uncertain) overall size , was found as one lump, later separated into three main fragments which ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epicyclic Carrier Locked
An epicyclic gear train (also known as a planetary gearset) is a gear reduction assembly consisting of two gears mounted so that the center of one gear (the "planet") revolves around the center of the other (the "sun"). A carrier connects the centers of the two gears and rotates, to carry the planet gear(s) around the sun gear. The planet and sun gears mesh so that their pitch circles roll without slip. If the sun gear is held fixed, then a point on the pitch circle of the planet gear traces an epicycloid curve. An epicyclic gear train can be assembled so the planet gear rolls on the inside of the pitch circle of an outer gear ring, or ring gear, sometimes called an ''annulus gear''. Such an assembly of a planet engaging both a sun gear and a ring gear is called a planetary gear train.J. J. Uicker, G. R. Pennock and J. E. Shigley, 2003, ''Theory of Machines and Mechanisms,'' Oxford University Press, New York.B. Paul, 1979, ''Kinematics and Dynamics of Planar Machinery'', Pren ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gear Ratio
A gear train or gear set is a machine element of a mechanical system formed by mounting two or more gears on a frame such that the teeth of the gears engage. Gear teeth are designed to ensure the Pitch circle diameter (gears), pitch circles of engaging gears roll on each other without slipping, providing a smooth transmission of rotation from one gear to the next. Features of gears and gear trains include: * The gear ratio of the pitch circles of mating gears defines the speed ratio and the mechanical advantage of the gear set. * A epicyclic gearing, planetary gear train provides high gear reduction in a compact package. * It is possible to design gear teeth for gears that are non-circular gear, non-circular, yet still transmit torque smoothly. * The speed ratios of chain drive, chain and belt (mechanical), belt drives are computed in the same way as gear ratios. See bicycle gearing. The transmission of rotation between contacting toothed wheels can be traced back to the Antikyt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Girard Desargues
Girard Desargues (; 21 February 1591September 1661) was a French mathematician and engineer, who is considered one of the founders of projective geometry. Desargues' theorem, the Desargues graph, and the crater Desargues on the Moon are named in his honour. Biography Born in Lyon, Desargues came from a family devoted to service to the French crown. His father was a royal notary, an investigating commissioner of the Seneschal's court in Lyon (1574), the collector of the tithes on ecclesiastical revenues for the city of Lyon (1583) and for the diocese of Lyon. Girard Desargues worked as an architect from 1645. Prior to that, he had worked as a tutor and may have served as an engineer and technical consultant in the entourage of Richelieu. Yet his involvement in the Siege of La Rochelle, though alleged by Ch. Weiss in ''Biographie Universelle'' (1842), has never been testified. As an architect, Desargues planned several private and public buildings in Paris and Lyon. As an e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bookwheel
The bookwheel (also written book wheel and sometimes called a reading wheel) is a type of rotating bookcase that allows one person to read multiple books in one location with ease. The books are rotated vertically similar to the motion of a water wheel, as opposed to rotating on a flat table surface. The design for the bookwheel originally appeared in a 16th-century illustration by Agostino Ramelli at a time when large books posed practical problems for readers. Ramelli's design influenced other engineers and, though now obsolete, inspires modern artists and historians. History and design The bookwheel, in its most commonly seen form, was invented in 1588 by Italian military engineer Agostino Ramelli, presented as one of the 195 designs in ''Le diverse et artificiose machine del Capitano Agostino Ramelli'' (''The various and ingenious machines of Captain Agostino Ramelli'').Brashear, Ronald"Ramelli's Machines: Original drawings of the 16th century machines" Smithsonian Librar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agostino Ramelli
Agostino Ramelli (1531–ca. 1610) was an Italian engineer best known for writing and illustrating the book of engineering designs ''Le diverse et artificiose machine del Capitano Agostino Ramelli'', which contains, among others, his design for the bookwheel. Ramelli was born in Ponte Tresa or Mesanzena, today in Switzerland. During the Siege of La Rochelle (1572–1573), he successfully engineered a mine under a bastion and breached the fortification,"One Good Turn: A Natural History of the Screwdriver and Screw" Witold Rybczynski p.47 making him popular with his commander, Henri d'Anjou, who later became King Henri III of France. In 1588, Ramelli published ''Le diverse et artificiose machine del Capitano Agostino Ramelli'', or ''The various and ingenious machines of Captain Agostino Ramelli''. The book contains 195 designs, over 100 of which are water-raising machines, such as water pumps or wells.Brashear, RonaldRamelli's Machines Smithsonian Libraries. Other d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Clock
An astronomical clock, horologium, or orloj is a clock with special mechanisms and dials to display astronomical information, such as the relative positions of the Sun, Moon, zodiacal constellations, and sometimes major planets. Definition The term is loosely used to refer to any clock that shows, in addition to the time of day, astronomical information. This could include the location of the Sun and Moon in the sky, the age and Lunar phases, the position of the Sun on the ecliptic and the current zodiac sign, the sidereal time, and other astronomical data such as the Moon's nodes for indicating eclipses), or a rotating star map. The term should not be confused with an ''astronomical regulator'', a high precision but otherwise ordinary pendulum clock used in observatories. Astronomical clocks usually represent the Solar System using the geocentric model. The center of the dial is often marked with a disc or sphere representing the Earth, located at the center of the S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richard Of Wallingford
Richard of Wallingford (1292–1336) was an English mathematician, astronomer, horologist, and cleric who made major contributions to astronomy and horology while serving as abbot of St Albans Abbey in Hertfordshire. Biography Richard was born, the son of a blacksmith, at Wallingford, Oxfordshire, Wallingford in Berkshire (now Oxfordshire) in England, in 1292. When he was orphaned he was taken to William de Kirkeby the Prior (ecclesiastical), Prior of Wallingford Priory and dedicated to the Holy Trinity. Wallingford was a dependant priory to St Albans Abbey. Richard subsequently spent six years studying at Oxford University before becoming a monk at St Albans. He later studied for nine more years at Oxford. In 1327 he became abbot of St Albans. Richard is best known for the astronomical clock he designed, while he was abbot, which is described in the ''Tractatus Horologii Astronomici'' (1327). The clock was completed about 20 years after Richard's death by William of Walsham ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apsidal Precession
In celestial mechanics, apsidal precession (or apsidal advance) is the precession (gradual rotation) of the line connecting the apsis, apsides (line of apsides) of an orbiting body, astronomical body's orbit. The apsides are the orbital points farthest (apoapsis) and closest (periapsis) from its primary (astronomy), primary body. The apsidal precession is the first time derivative of the argument of periapsis, one of the six main orbital elements of an orbit. Apsidal precession is considered positive when the orbit's axis rotates in the same direction as the orbital motion. An apsidal period is the time interval required for an orbit to precess through 360°, which takes the Earth about 112,000 years and the Moon about 8.85 years. History The ancient Greek astronomer Hipparchus noted the apsidal precession of the Moon's orbit (as the revolution of the Moon's apogee with a period of approximately 8.85 years); it is corrected for in the Antikythera Mechanism (circa 80 BC ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbit Of The Moon
The Moon orbits Earth in the retrograde and prograde motion, prograde direction and completes one orbital period, revolution relative to the March Equinox, Vernal Equinox and the fixed stars in about 27.3 days (a tropical month and sidereal month), and one revolution relative to the Sun in about 29.5 days (a synodic month). On average, the lunar distance, distance to the Moon is about from Earth's centre, which corresponds to about 60 Earth radii or 1.28 light-seconds. Earth and the Moon orbit about their barycentre (common centre of mass), which lies about from Earth's centre (about 73% of its radius), forming a satellite system called the Earth–Moon system. With a mean orbital speed around the barycentre of , the Moon covers a distance of approximately its diameter, or about half a degree on the celestial sphere, each hour. The Moon differs from most Regular moon, regular satellites of other planets in that its orbital plane (astronomy), orbital plane is closer to the ec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epitrochoid
In geometry, an epitrochoid ( or ) is a roulette traced by a point attached to a circle of radius rolling around the outside of a fixed circle of radius , where the point is at a distance from the center of the exterior circle. The parametric equations for an epitrochoid are: :\begin & x (\theta) = (R + r)\cos\theta - d\cos\left(\theta\right) \\ & y (\theta) = (R + r)\sin\theta - d\sin\left(\theta\right) \end The parameter is geometrically the polar angle of the center of the exterior circle. (However, is not the polar angle of the point (x(\theta),y(\theta)) on the epitrochoid.) Special cases include the limaçon with and the epicycloid with . The classic Spirograph toy traces out epitrochoid and hypotrochoid curves. The paths of planets in the once popular geocentric system of deferents and epicycles are epitrochoids with d>r, for both the outer planets and the inner planets. The orbit of the Moon, when centered around the Sun, approximates an epitrochoid. The com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
