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Coupled Elevators?



In the "energy" exchange on this list, there has been a reference to one
elevator gaining energy while another elevator is losing energy. I don't
have statistics to support this, but I would guess over 99% of elevators do
not work this way.

Cable elevators have counterweights. If two elevators served as the
counterweights for each other, they would have to run coupled... each
stopping when the other stopped. Have you ever been in an elevator that
works this way? You're on the 40th floor, you press the lobby button, no
other buttons are pressed, yet you stop at the 34th, 28th, 23rd, 15th, 8th
floors because someone was getting out on those floors from the other
elevator going up? I never have been. The only coupled elevators I am
aware of are those serving two fixed locations and operated by an attendant.
I think I was told that the elevator into Carlsbad Caverns works this way;
one group of people goes down at the same time another group comes up. But
in general, elevators do not work this way.

Also, for short buildings (2 to 5 floors) the elevator is often hydraulic
and doesn't have a cable or counterweight.

I know this is nitpicking, but this is not the only time I have seen this
description used (one elevator gaining energy while a coupled one loses
energy). It seems to me we ought to keep our examples more true to life.
It would be easy to fix this by talking about the energy gain/loss of the
"counterweight."


Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817