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Thread: Most Rotations? - Theoretical Question

  1. #1 Most Rotations? - Theoretical Question 
    New Member
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    Dec 2009
    Hello there, I'm new here!

    I would like to discuss a question which has been on my mind for many years:

    What man-made object, past or present, has rotated the greatest number of times?

    Having given this some thought I've considered the turbines in the Hoover dam at
    minutes in a year, 73 years old at 180rpm = 6,906,384,000 rotations

    Or the jet engine on passenger aircraft which can spin at several thousand rpm and some have been in service for a few decades. 5000rpm for a quarter if its life of 30 years = 19,710,000,000

    Turbochargers often hit 100,000 rpm. There are plenty around that are 20 years old in long daily use. At 50,000 rpm for a quarter of its life = 131,400,000,000

    What else could be a contender?

    Best regards, Fergus

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  3. #2  
    Forum Freshman Solveer's Avatar
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    Dec 2009
    Interesting question... though more of a poll than a question I guess.

    My addition to this list would have to be the gears on the Big Ben Tower. It's been running for a bit over 150 years now and assuming there is a single gear that is (and has been since day one) ticking every second, you would get 4,730,400,000 ticks (and probably about just as many revolutions on some gears).
    Keep in mind though that parts wear out and it is likely that some of these "high" numbers were probably obtained on multiple replacement parts.

    regarding jet engines, I wanted to add (since I worked as a propulsion engineer on a small jet=high rpm) that the high pressure side can easily go into the range of 50,000 rpm. These jets usually have a life of about 20 years (that's equivalent to 20,000 hours). The high speed side will have 60 billion revolutions on their clock (with plenty of assumptions).... but again, the actual bearings will likely have been replaced at least once in that time.

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