"Effective, Precise, and Reliable… In short: Unbeatable"
Fortis, Sinn, and Tutima insisted on the continuation of production because the 5100 is the only calibre that met their military requirements. The 5100, due to its construction, is the only chronograph movement that can withstand large shocks without its chronograph seconds hand stopping. This is because its chronograph mechanism is driven directly unlike most other chronographs which use an intermediate wheel. The calibre easily withstands acceleration 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 without servicing. Service intervals from four to seven years have shown to be sufficient.
“Antiquated
but Reliable”
- The Lemania 5100 demonstrates other unusual constructions. The navette-type chronograph mechanism is fitted not as usually between the base plate and the automatic winding system but between the dial and the base plate instead. The rotor winds in one direction only over the reduction gear and runs in a hard iron bearing instead of jewels. The ratchet wheel under the rotor transfers the rotation of the rotor to a reduced wheel. The yoke spring on the rotor doubles as a click. The above clearly shows that the Lemania 5100’s antiquated construction, while simple, is nonetheless reliable and functional. The clutch wheel is also made out of nylon, another tribute to rational production. The large mainspring barrel continues the rugged design philosophy of the movement. The balance is also quite large for a high beat movement running at 28’800A/h. The calibre uses the reliable and space-saving Triovis regulator. Kif-Flector shock absorber was chosen instead of the more usual Incabloc shock absorber seen in ETA calibre. At 8.2mm, the 5100 is 0.3mm taller than the ETA-Valjoux 7750. This makes the 5100 the tallest of today’s chronograph calibre.
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