Girard Perregaux

cazalea
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4 Reasons for the disappearance of central minutes

A. 4 concentric shafts is a greater challenge for the manufacture to machine
B. 4 hands one above the other increases the risk of hands touching each other
C. 4 in the center increases the thickness of the watch, but sub-dials do not
D. The Lemania 5100 was the popular choice of 4-hand movement

I also found this information from an article old (way back before 2000):

Nouvelle Lemania planned to end production of the 5100, a rugged but accurate calibre used mostly in military and space applications. The simplistic design of the 5100 no longer fitted the manufacturer’s product line and philosophy. The tools for the movement were outdated and in need of restoration. The investment couldn’t be justified by the limited sales to its 3 main customers: Fortis, Sinn, and Tutima (Omega, Orfina/Porsche Design, Paul Picot & Alain Silberstein also used a few 5100s each year).

Fortis, Sinn, and Tutima insisted on the continuation of the 5100 as it met their military requirements. The 5100 was the only chronograph movement able to withstand large shocks without its chrono seconds hand stopping, because its chronograph mechanism is driven directly (unlike most other chronographs which use an intermediate wheel). The calibre can withstand in excess of 7G without appreciable loss of accuracy. Its ruggedness is legendary; the calibre easily absorbs shocks and blows. The calibre also maintains its accuracy over long periods; service intervals at 4-7 years are sufficient.

One of the 5100’s weaknesses is its simple, archaic construction. Like a cheap alarm clock, it uses pillar construction. The cock and bridges are attached to the main plate by thin pillars. In a more modern design, the cock and bridges mount directly onto the main plate. Pillar construction reduces manufacturing cost since parts can be stamped as opposed to being milled. The designers also used nylon parts in the movement, which lowered production costs and was deemed to be progressive. The day and date wheels of the 5100 and their cams are nylon. On the periphery of the movement are two gray nylon half-moons that support the rotor and absorb shocks from the rotor in case of hard blows. This nylon “ring” around the movement conveniently hides the pillar construction from the viewer.

Ultimately, Lemania did not cease production of the 5100 in 1997. However, the wholesale price doubled from about 200 SFR to 400 SFR and it died in 2002-2004 or thereabouts. 

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