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Cycloid Gear
A cycloidal gear is a toothed gear with a cycloidal profile. Such gears are used in mechanical clocks and watches, rather than the involute gear form used for most other gears. Cycloidal gears have advantages over involute gears in such applications in being able to be produced flat (making them easier to polish, and thereby reduce friction), and having fewer points of contact (both reducing friction and wear). Their gear tooth profile is based on the epicycloid and hypocycloid curves, which are the curves generated by a circle rolling around the outside and inside of another circle, respectively. Characteristics When two toothed gears mesh, an imaginary circle, the ''pitch circle'', can be drawn around the centre of either gear through the point where their teeth make contact. The curves of the teeth outside the pitch circle are known as the ''addenda'', and the curves of the tooth spaces inside the pitch circle are known as the ''dedenda''. An addendum of one gear rests ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horology
Chronometry or horology () is the science studying the measurement of time and timekeeping. Chronometry enables the establishment of standard measurements of time, which have applications in a broad range of social and scientific areas. ''Horology'' usually refers specifically to the study of mechanical timekeeping devices, while ''chronometry'' is broader in scope, also including biological behaviours with respect to time (biochronometry), as well as the dating of geological material (geochronometry). Horology is commonly used specifically with reference to the mechanical instruments created to keep time: clocks, watches, clockwork, sundials, hourglasses, Water clock, clepsydras, timers, time recorders, marine chronometers, and atomic clocks are all examples of Measuring instrument, instruments used to measure time. People interested in horology are called ''horologists''. That term is used both by people who deal professionally with timekeeping apparatuses, as well as enthus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cycloidal Drive
A cycloidal drive or cycloidal speed reducer is a mechanism for reducing the speed of an input shaft by a certain ratio. Cycloidal speed reducers are capable of relatively high ratios in compact sizes with very low backlash. The input shaft drives an eccentric bearing that in turn drives the cycloidal disc in an eccentric, cycloidal motion. The perimeter of this disc is geared to a stationary ring gear and has a series of output shaft pins or rollers placed through the face of the disc. These output shaft pins directly drive the output shaft as the cycloidal disc rotates. The radial motion of the disc is not translated to the output shaft. Theory of operation The input shaft is mounted eccentrically to a rolling-element bearing (typically a cylindrical roller bearing), causing the cycloidal disc to wobble in a circle. The cycloidal disc will independently rotate around the bearing as it is pushed against the ring gear. This is similar to planetary gearing. The direction o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Involute
In mathematics, an involute (also known as an evolvent) is a particular type of curve that is dependent on another shape or curve. An involute of a curve is the Locus (mathematics), locus of a point on a piece of taut string as the string is either unwrapped from or wrapped around the curve. The evolute of an involute is the original curve. It is generalized by the Roulette (curve), roulette family of curves. That is, the involutes of a curve are the roulettes of the curve generated by a straight line. The notions of the involute and evolute of a curve were introduced by Christiaan Huygens in his work titled ''Horologium Oscillatorium, Horologium oscillatorium sive de motu pendulorum ad horologia aptato demonstrationes geometricae'' (1673), where he showed that the involute of a cycloid is still a cycloid, thus providing a method for constructing the cycloidal pendulum, which has the useful property that its period is independent of the amplitude of oscillation. Involute of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cycloid
In geometry, a cycloid is the curve traced by a point on a circle as it Rolling, rolls along a Line (geometry), straight line without slipping. A cycloid is a specific form of trochoid and is an example of a roulette (curve), roulette, a curve generated by a curve rolling on another curve. The cycloid, with the Cusp (singularity), cusps pointing upward, is the curve of fastest descent under uniform gravity (the brachistochrone curve). It is also the form of a curve for which the Frequency, period of an object in simple harmonic motion (rolling up and down repetitively) along the curve does not depend on the object's starting position (the tautochrone curve). In physics, when a charged particle at rest is put under a uniform Electric field, electric and magnetic field perpendicular to one another, the particle’s trajectory draws out a cycloid. History The cycloid has been called "The Helen of Geometers" as, like Helen of Troy, it caused frequent quarrels among 17th-centur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Étienne Louis Camus
Charles Étienne Louis Camus (25 August 1699 – 2 February 1768), was a French mathematician and mechanician who was born at Crécy-en-Brie, near Meaux. He studied mathematics, civil and military architecture, and astronomy after leaving Collège de Navarre in Paris. In 1730 he was appointed professor of architecture and, in 1733, associate of the Académie des Sciences. He also became a professor of geometry, secretary to the Academy of Architecture and fellow of the Royal Society of London. In 1727 he presented a memoir to the academy on masting ships, in consequence of which he was named the same year joint mechanician to that body. In 1736 he accompanied Pierre Louis Maupertuis and Alexis Clairaut in the expedition to Lapland for the measurement of a degree of meridian arc. He was the author of a ''Cours de mathématiques'' (Paris, 1766), and a number of essays on mathematical and mechanical subjects. In 1760 he became perpetual secretary of the academy of architecture. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ole Rømer
Ole Christensen Rømer (; 25 September 1644 – 19 September 1710) was a Danes, Danish astronomer who, in 1676, first demonstrated that light travels at a finite speed. Rømer also invented the modern thermometer showing the temperature between two fixed points, namely the points at which water respectively boils and freezes. Rømer made his discovery regarding the speed of light while working at the Paris Observatory, Royal Observatory in Paris and studying Jupiter's moon Io (moon), Io. He estimated that light takes about 11 minutes to travel from the Sun to Earth. Using today's knowledge of the Astronomical unit, Sun-Earth distance, this would amount to a speed of light of approximately 220,000 kilometers per second, compared to today's accepted value of just under 300,000 kilometers per second. In scientific literature, alternative spellings such as "Roemer", "Römer", or "Romer" are common. Biography Rømer was born on 25 September 1644 in Aarhus to merchant and skipper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Philippe De La Hire
Philippe de La Hire (or Lahire, La Hyre or Phillipe de La Hire) (18 March 1640 – 21 April 1718)"LA HIRE, Philippe de." ''Benezit Dictionary of Artists''. Oxford Art Online (subscription required). Oxford University Press, accessed May 29, 2016. was a French , , , and .Chareix 2008 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gérard 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 eng ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gothic Arch
A pointed arch, ogival arch, or Gothic arch is an arch with a pointed crown meet at an angle at the top of the arch. Also known as a two-centred arch, its form is derived from the intersection of two circles. This architectural element was particularly important in Gothic architecture. The earliest use of a pointed arch dates back to bronze-age Nippur. As a structural feature, it was first used in eastern Christian architecture, Byzantine architecture and Sasanian architecture, but in the 12th century it came into use in France and England as an important structural element, in combination with other elements, such as the rib vault and later the flying buttress. These allowed the construction of cathedrals, palaces and other buildings with dramatically greater height and larger windows which filled them with light. Early arches Crude arches pointed in shape have been discovered from the Bronze Age site of Nippur dated earlier than 2700 BC. The palace of Nineveh also has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roots Blower
The Roots blower is a positive displacement lobe pump which operates by pumping a fluid with a pair of meshing lobes resembling a set of stretched gears. Fluid is trapped in pockets surrounding the lobes and carried from the intake side to the exhaust. The Roots blower design does not incorporate any reduction in volume/increase in pressure as air or other fluid passes through, hence it can best be described as a blower rather than a supercharger unlike some other designs of "supercharger" such as cozette, centric, Shorrock supercharger, Powerplus supercharger and also the axial flow Eaton type supercharger which have internal "compression". The most common application of the Roots-type blower has been the induction device on two-stroke diesel engines, such as those produced by Detroit Diesel and Electro-Motive Diesel. Roots-type blowers are also used to supercharge four-stroke Otto cycle engines, with the blower being driven from the engine's crankshaft via a toot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
