A photo pop quiz to get the gears moving

No geography trivia quiz this week (still looking for ideas in case anyone has any). Instead, a different kind of challenge:

What are these?

UPDATE: After a dozen interesting guesses, Pascal gets it right: They’re metro turnstiles.

Old metro turnstiles

A sea of old turnstiles behind a gate at Pie-IX metro

Turnstile innards, with unrelated celebratory horn

These photos were taken at the Pie-IX metro station, where dozens of the old turnstiles have gone to die. They have been replaced by new Opus-enabled turnstiles, except for the one at each station that was kept for transition purposes (those will be joining them soon) and some exit-only turnstiles that don’t need to be replaced.

14 thoughts on “A photo pop quiz to get the gears moving

  1. Clement Côté


    The shape above the main gear is some kind of driver. As the gear turn, it makes the arm on the right oscillate according to a repeating pattern. Household sewing machines have similar mechanisms.

    So, a complete random guess: An industrial sewing machine?

  2. Clement Côté

    Ok then, more guessing.

    It’s part of some engine, specifically either an injection mechanism or an exhaust?

  3. mare

    These are metro tire cutters at the end of the track (tracks in this case) so the train sinks with the rims onto the track and thus brakes (violently) before it hits the end barrier.

    (I totally make this up, but it sounds plausible, doesn’t it?)

  4. Clement Côté

    My last guess: It’s the mechanism used to shift one of three images on these giant billboards, like the VW one on 15 south.

  5. Rich

    Back in the late ’70s my older brother actually decoded the punch-hole scheme used to record the date and time on the the bus transfers. I don’t remember the details but it turned out that the days wrapped around fairly quickly, so he kept a stack of them handy and managed to ride the metro for free often enough to significantly augment his lunch money. Not very surprisingly he grew up to be a major computer nerd as an adult.


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