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The Encyclopedia of Horology

Calibre database

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Specifications

FieldIllinois Bunn Special (60-hour grades)
Makerillinois-watch-company
CountryUnited States
PeriodLate 1920s to the early 1930s, with assembly from parts continuing after the Hamilton purchase
Diameter16 size
HeightNot consistently documented across grades
Jewels21 or 23 depending on grade
Frequency18,000 vph (2.5 Hz)
Power reserveMarked as approximately 60 hours, from which the grades take their collector name
WindingStem wind
SettingLever set on railway-service examples
EscapementSwiss lever with jewelled pallets
BalanceCompensation balance with micrometric regulator
ComplicationsSubsidiary seconds
ArchitectureThree-quarter plate railroad-grade movement with a long-running barrel arrangement marked for a 60-hour run, produced in the final independent years of the Illinois Watch Company.