Editing Antikythera mechanism (section)

===Proposed gear schemes===
Because of the large space between the mean Sun gear and the front of the case and the size of and mechanical features on the mean Sun gear, it is very likely that the mechanism contained further gearing that either has been lost in or subsequent to the shipwreck, or was removed before being loaded onto the ship.<ref name=freeth-12/> This lack of evidence and nature of the front part of the mechanism has led to attempts to emulate what the Ancient Greeks would have done and because of the lack of evidence, many solutions have been put forward over the years. But as progress has been made on analyzing the internal structures and deciphering the inscriptions, earlier models have been ruled out and better models developed.<ref name=FrontCover/><ref name=Freeth2016/>

{{multiple image| direction = vertical| width = 150| image1 = Antikythera-proposed-4.svg| caption1 = Wright proposal| image2 = Antikythera-proposed-1.svg| caption2 = Evans et al. proposal| image3 = Antikythera-proposed-3.svg| caption3 = 2012 Freeth et al. proposal<ref name=freeth-12/>}}

[[Derek J. de Solla Price]] built a simple model in the 1970s.<ref name=price-74/>

In 2002 [[Michael T. Wright (curator)|Michael Wright]] designed and built the first workable [https://www.youtube.com/watch?v=4eUibFQKJqI model] with the known mechanism and his emulation of a potential [[planetarium]] system. He suggested that along with the lunar anomaly, adjustments would have been made for the deeper, more basic solar anomaly (known as the "first anomaly"). He included pointers for this "true sun", Mercury, Venus, Mars, Jupiter, and Saturn, in addition to the known "mean sun" (current time) and lunar pointers.<ref name=freeth-12/>

Evans, Carman, and Thorndike published a solution in 2010 with significant differences from Wright's.<ref name=cte-10/> Their proposal centred on what they observed as irregular spacing of the inscriptions on the front dial face, which to them seemed to indicate an off-centre sun indicator arrangement; this would simplify the mechanism by removing the need to simulate the solar anomaly. They suggested that rather than accurate planetary indication (rendered impossible by the offset inscriptions) there would be simple dials for each individual planet, showing information such as key events in the cycle of planet, initial and final appearances in the night sky, and apparent direction changes. This system would lead to a much simplified gear system, with much reduced forces and complexity, as compared to Wright's model.<ref name=cte-10/>

Their proposal used simple meshed gear trains and accounted for the previously unexplained 63 toothed gear in fragment D. They proposed two face plate layouts, one with evenly spaced dials, and another with a gap in the top of the face, to account for criticism that they did not use the apparent fixtures on the b1 gear. They proposed that rather than bearings and pillars for gears and axles, they simply held weather and seasonal icons to be displayed through a window.<ref name=cte-10/> In a paper published in 2012, Carman, Thorndike, and Evans also proposed a system of epicyclic gearing with pin and slot followers.<ref name=cte-12/>

Freeth and Jones published a proposal in 2012. They proposed a compact and feasible solution to the question of planetary indication. They also propose indicating the solar anomaly (that is, the sun's apparent position in the zodiac dial) on a separate pointer from the date pointer, which indicates the mean position of the Sun, as well as the date on the month dial. If the two dials are synchronised correctly, their front panel display is essentially the same as Wright's. Unlike Wright's model however, this model has not been built physically, and is only a 3-D computer model.<ref name=freeth-12/>

[[Image:Gearing Relationships of the Antikythera Mechanism.svg|thumb|upright|Internal gearing relationships of the Antikythera Mechanism, based on the Freeth and Jones proposal]]

The system to synthesise the solar anomaly is very similar to that used in Wright's proposal: three gears, one fixed in the centre of the b1 gear and attached to the Sun spindle, the second fixed on one of the spokes (in their proposal the one on the bottom left) acting as an idle gear, and the final positioned next to that one; the final gear is fitted with an offset pin and, over said pin, an arm with a slot that in turn, is attached to the sun spindle, inducing anomaly as the mean Sun wheel turns.<ref name=freeth-12/>

The inferior planet mechanism includes the Sun (treated as a planet in this context), Mercury, and Venus.<ref name=freeth-12/> For each of the three systems, there is an epicyclic gear whose axis is mounted on b1, thus the basic frequency is the Earth year (as it is, in truth, for epicyclic motion in the Sun and all the planets—excepting only the Moon). Each meshes with a gear grounded to the mechanism frame. Each has a pin mounted, potentially on an extension of one side of the gear that enlarges the gear, but doesn't interfere with the teeth; in some cases, the needed distance between the gear's centre and the pin is farther than the radius of the gear itself. A bar with a slot along its length extends from the pin toward the appropriate coaxial tube, at whose other end is the object pointer, out in front of the front dials. The bars could have been full gears, although there is no need for the waste of metal, since the only working part is the slot. Also, using the bars avoids interference between the three mechanisms, each of which are set on one of the four spokes of b1. Thus there is one new grounded gear (one was identified in the wreckage, and the second is shared by two of the planets), one gear used to reverse the direction of the sun anomaly, three epicyclic gears and three bars/coaxial tubes/pointers, which would qualify as another gear each: five gears and three slotted bars in all.<ref name=freeth-12/>

The superior planet systems—Mars, Jupiter, and Saturn—all follow the same general principle of the lunar anomaly mechanism.<ref name=freeth-12/> Similar to the inferior systems, each has a gear whose centre pivot is on an extension of b1, and which meshes with a grounded gear. It presents a pin and a centre pivot for the epicyclic gear which has a slot for the pin, and which meshes with a gear fixed to a coaxial tube and thence to the pointer. Each of the three mechanisms can fit within a quadrant of the b1 extension, and they are thus all on a single plane parallel with the front dial plate. Each one uses a ground gear, a driving gear, a driven gear, and a gear/coaxial tube/pointer, thus, twelve gears additional in all.

In total, there are eight coaxial spindles of various nested sizes to transfer the rotations in the mechanism to the eight pointers. So in all, there are 30 original gears, seven gears added to complete calendar functionality, 17 gears and three slotted bars to support the six new pointers, for a grand total of 54 gears, three bars, and eight pointers in Freeth and Jones' design.<ref name=freeth-12/>

On the visual representation Freeth provides, the pointers on the front zodiac dial have small, round identifying stones. He refers to a quote from an ancient papyrus:

{{blockquote|...a voice comes to you speaking. Let the stars be set upon the board in accordance with [their] nature except for the Sun and Moon. And let the Sun be golden, the Moon silver, Kronos [Saturn] of obsidian, Ares [Mars] of reddish onyx, Aphrodite [Venus] lapis lazuli veined with gold, Hermes [Mercury] turquoise; let Zeus [Jupiter] be of (whitish?) stone, crystalline (?)...<ref name=papyrus/>}}

However, more recent discoveries and research have shown that the above models are not correct. In 2016, the numbers 462 and 442 were found in [[computed tomography]] scans of the inscriptions dealing with Venus and Saturn, respectively.<ref name=FrontCover/> These relate to the [[synodic cycle]]s of these planets, and indicated that the mechanism was more accurate than previously thought.
In 2018, based on the CT scans, the Antikythera Mechanism Research Project proposed changes in gearing and produced mechanical parts based on this.<ref name="Auto82-40"/>

In March 2021, the Antikythera Research Team at [[University College London]], led by Freeth, published a new proposed reconstruction of the entire Antikythera Mechanism. They were able to find gears that could be shared among the gear-trains for the different planets, by using rational approximations for the synodic cycles which have small prime factors, with the factors 7 and 17 being used for more than one planet. They conclude that none of the previous models "are at all compatible with all the currently known data", but their model is compatible with it.<ref name="Freeth2016"/><ref name="Auto82-41"/>
Freeth has directed a video explaining the discovery of the synodic cycle periods and the conclusions about how the mechanism worked.<ref name="Auto82-42"/>

In 2025 researchers using a computer simulation of the mechanism that took into account the exact shape of the teeth in its gears, concluded that it would have jammed and stopped working after 4 months.<ref>{{cite arXiv |eprint=2504.00327 |author1=Esteban Guillermo Szigety y Gustavo Francisco Arenas |title=The Impact of Triangular-Toothed Gears on the Functionality of the Antikythera Mechanism |date=2025 |class=astro-ph.IM }}</ref>