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Related to epicyclic: progenitive, epicyclic gear train


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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(ep -ă-sÿ-kăl) See Ptolemaic system.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006


(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.

The Astrology Book, Second Edition © 2003 Visible Ink Press®. All rights reserved.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



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.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


The circle which generates an epicycloid or hypocycloid.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Keruvannya zminamy shvydkosti za dopomohoyu nepovnoyi dyferentsial'noyi peredachi cherez satelit [Speed Change Management Via Partial Epicyclic Gear Train Through Planets].
McFadden, "Window functions for the calculation of the time domain averages of the vibration of the individual planet gears and sun gear in an epicyclic gearbox," Journal of Vibration and Acoustics, vol.
Singh, "Epicyclic load sharing map: development and validation," Mechanism and Machine Theory, vol.
By way of comparison, a Pratt & Whitney GTF hub-mounted epicyclic gear box is shown in Fig.
Then we have "epicyclic", which is an irregularity usually due to a static imbalance and no matter how fast you spin an object it will rotate in a small circle which moves around the circumference of a larger circle.
By combining the load distribution principle of epicyclic gears with the simplified design of a parallel shaft gear, operating efficiencies of 99 per cent are possible.
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.
He created crisp transmission change with the invention of the epicyclic gearbox.
Hence the pilgrims' regress towards the primal sinner via the descent of Geryon is re-encrypted in their epicyclic descent into actual hypocrisy."