epicycle

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Related to epicyclic: progenitive, epicyclic gear train

epicycle:

see Ptolemaic systemPtolemaic system
, historically the most influential of the geocentric cosmological theories, i.e., theories that placed the earth motionless at the center of the universe with all celestial bodies revolving around it (see cosmology).
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epicycle

(ep -ă-sÿ-kăl) See Ptolemaic system.

Epicycle

(religion, spiritualism, and occult)

When Earth was viewed as the stationary center of the universe, the retrograde motion of the planets was explained in terms of epicycles—smaller orbits that circled in the reverse direction from the planets’ usual motion.

Epicycle

 

an auxiliary circle in Ptolemy’s geocentric system of the world.

Epicycles were introduced to explain the retrograde motions of the planets. It was presumed that a planet moves uniformly along the epicycle while its center E (see Figure 1) moves along another circle, called the deferent, with its center at the earth. Because a deferent with one epicycle could not explain many irregularities in the motions of the planets, systems of epicycles were introduced. It was believed that the center of the second epicycle moved along the first epicycle, while the center of the third epicycle

Figure 1

moved, in turn, along the second epicycle, and so on. The planet is located in the last epicycle.

epicycle

[′ep·ə‚sī·kəl]
(mathematics)
The circle which generates an epicycloid or hypocycloid.
References in periodicals archive ?
At first glance, the construction of the BHS power distribution gear is very similar to that of a standard epicyclic gear: Three planet gears are arrayed around a central sun pinion.
However, it is clear that Galileo believed Copernicus' epicyclic heliostatic system was real.
It employs a compound epicyclic system of gearing to provide high-torque capacity and a wide range of reduction ratios in a compact space.
A double-cut knife system and epicyclic knife drive allow for harvesting speeds up to II miles (17.
The data sheet provides technical information on planetary epicyclic drives, differential phase shifters, position control and narrow band transmissions, machine tool spindle drives, multi-speed, variable speed, right angle and reversing drives, and servo drive reducers.
The acetal created a compact, epicyclic design that allowed better load sharing.
These were considerations taken up in the Almagest that led to Ptolemy's modifications of the epicyclic models of his predecessors, namely to the creation of the eccentric and equant models of the planets.
The flywheel is connected to the output end of the gearbox via an epicyclic gearset between the Torotrak-licensed CVT (www.
The research engine will use an electro-hydraulic valvetrain to do this, although a cheaper mechanical system using an epicyclic gearset could also be used, and would be the company's preferred option for the future if it proves as effective, said Dave Greenwood, chief engineer for advanced technology at Ricardo.
Epicyclic roller gear, Patent WO 94/12812 (WIPO), 06.
The topics include the evolution of the idea of abstract groups, Artin's theory of braids and the algebraization of topology, the mathematical structure of the eccentric and epicyclic models in ancient Greece and India, divisibility and primalty in Vedic literature, and paradoxes in hydrodynamics.