Railroad chronometer
From Wikipedia, the free encyclopedia
Railroad chronometers (railroader's watches) are specialized timepieces that once were crucial for safe and correct operation of trains in the United States and Canada. A system called Timetable and Train Order, which relied on highly accurate timekeeping, was used to ensure that two trains could not be on the same stretch of track at the same time.
After a serious train accident in Ohio in 1891, caused by the malfunction of an engineer's watch, the North American railroad industry charged its General Time Inspector, Webb C. Ball, to establish unified standards for all the watches used by personnel among the participating railroad companies:
- only American-made watches may be used (depending on availability of spare parts)
- only open-faced dials, with the stem at 12 o’clock
- minimum of 17 functional jewels in the movement, 16 or 18-size only
- maximum variation of 30 seconds (approximately 4 seconds daily) per weekly check
- watch adjusted to five positions (face up, face down, crown up, crown down, or sideways)
- adjusted for severe temperature variance and isochronism (variance in spring tension)
- indication of time with bold legible Arabic numerals, outer minute division, second dial, heavy hands,
- lever used to set the time (no risk of having the stem left out, thus inadvertently setting the watch to an erroneous time)
- Breguet balance spring
- micrometer adjustment regulator
- double roller
- steel escape wheel
- anti-magnetic protection (after the advent of diesel locomotives)
The Waltham Watch Company quickly complied with the requirements of Ball's guidelines, as soon did the Ball Watch Company, Elgin Watch Company, Hamilton Watch Company, Illinois Watch Company and most of the other American watch manufacturers, all applying the American System of Watch Manufacturing.
The Time Signal Service of the United States Naval Observatory was used to ensure accuracy of railroad chronometers and schedule American rail transport.
The minimum requirements were raised several times as watch-making technology progressed, and the watch companies produced newer, even more reliable models. By WWII, many railroads required watches that were of a much higher grade (as many as 23 jewels, for example) than those made to comply with the original 1891 standard.
