We took a household journey with our grandsons to the New York Transit Museum in Brooklyn, NY. Retired subway automobiles had been on show, a few of them seemingly not that previous whereas others dated approach, approach again. Guests may freely roam out and in. I used to be on this one automobile that had been in service in 1903 which meant it predated the arrival of electronics. Even the vacuum tube had not but been invented by then.
I seen the passenger space’s naked gentle bulbs and acquired actually shut to at least one (Determine 1). It was rated at 56 watts and 120 volts. A query got here to thoughts as to how did that automobile use 120-volt gentle bulbs when the third rail voltage was (and nonetheless is) 600 volts DC?
Determine 1 A subway automobile gentle bulb up shut exhibiting 56-W and 120-V ranking.
Once we acquired dwelling, I attempted wanting up subway automobile technical knowledge, however after I got here to a wiring schematic, I couldn’t learn it. The symbols had been indecipherable to me. Solely then did it daybreak on me that 5 such bulbs linked in sequence can be operable from 120 x 5 = 600 volts. If any one of many 5 had been to burn out, all 5 would go darkish, however then upkeep would change all 5 and discard 4 good bulbs with the one blown out bulb. It sounded wasteful, however it could have been a sensible method.
Is that the precise fact? I don’t know, and there was no person readily available to ask, even when I had been fast sufficient of wit to inquire. Additionally, I simply wasn’t good sufficient on website to see if the full variety of bulbs within the automobile was a a number of of 5. Perhaps at some point, I can do this.
One other level about these subway bulbs is that that they had left-handed threads on their bases, whereas family bulbs use right-handed threads. This was to discourage gentle bulb thefts. Stolen bulbs wouldn’t match into gentle bulb sockets in households, solely into the sockets of subway automobiles.
John Dunn is an electronics advisor, and a graduate of The Polytechnic Institute of Brooklyn (BSEE) and of New York College (MSEE).
Associated Content material
- The draw back of overdesign, Half 2: A Dunn historical past
- The draw back of overdesign
- Motograph Information Bulletin debuts in New York Metropolis, November 6, 1928
- 1st industrial elevator begins operating, March 23, 1857
The publish Vintage NYC subway automobiles appeared first on EDN.
