The Providence news. (Providence [R.I.]) 1891-1906, 1893-11-27
MODERN LEG SAVERS.
AN INTERESTING ACCOUNT OF HOW
THE ELEVATORS WORK.

Garry 10000 Persons Day--How Some
of Them Are Operated BY Water Power.
Five hundred thousand men ride In the
elevators OF New York city every day OF
tho year, and not one man Of them In
hundred has more than the vaguest idea
how these shooting cars work. As for
the 100, 900 or % women who daily call
out sup" or "down," the percentage who
know what "makes the thing 60" would
be shockingly small.
To get some more precise ideas about
thsse vertical railways, the writer went
down the other day into subteranoan
New York, into those wonderful modern
tricity takes its birth, Under one OF the
great down town buildings, which con-
tains no less than 81 elevators, 81 for pas
sengers, 1S for freight.
A strange and unfamiliar region Is this,
where giant wheels, belted to other
wheels, make the foundations trcmble and
the air roar In ones ears.
"Here," said the engineer, 20 whom all
this was as familiar as the schoolroom to
It's teacher, "here are the boilers which
supply steam TO work the elevator pumps
and 10 turn the dynamos. There sra nine
of them, each 10 feet long and feet In
diameter. They burn 1s5 tons Of coal .
week, winter and summer. The seasons
make very little difference; h In always
the same down hsre.
"Now oome this way, and you viii see
how this steam makes the pumps send
water up TO the tanks at the top OF the
buiiding-5,0 900 gallons Of IL minute.
Say they work at full pressure half the
time, or four hours day, that gives l:o,-
900 gallons pumped up about 900 feet,
which means nearly 4o,0oo,0o0 foot
pounds OF energy . day to run the Gle
vators alone.
"Not no bad, IS its And the beauty Of
it In that in doing this work we use the
water over and over again pumped into
the tanks above, then discharged into the
big tank down here, then through the
pumps again aud 90 on until VIC change 10
for cleanliness.
"And how does the water run through
the clevatorsi"
'sI can make that plain to you in two
minutes. You sec each elevator has its
water tank at the top Of the building and
its own hydraulic machine ht the bottom,
and the two are connected By an inch
iron pipe. That pipe lets the water from
above into the 8 foot cylinder OF the hy-
draulic machine, and this water in kept by
the pumps at pressure of 100 pounds to
the square inch.
consequently whenever the water
presses into the cylinder it drives this pis-
ton rod out to It's full length, 10 feet, with
the force Of some scores of tons-the cal
culation is easy il you remember the for
mula. Now this piston rod in moving
pulls apart what you might call the two
blocks OF an enormous pulley, with i've
wheels in each block.
"Here they are, see And the wire rope
which runs around these pulley wheels
goes over wheel up under the roof, and
then down till it catches the top of the
elevator car As there are 10 wheels In
the two pulley blocks the end Of the rope
with the car attached travels 10 times as
far a. the piston rod does, or 10 times 16
feet, which is the distance the elevator
travels up and down"
what brings the piston back and the
elevator downf
.The changing of this valve where the
iron pipe joins the cylinder. When the
valve is thrown one way, the water presses
into the cylinder, and up goes the ele-
vator; when the valve Is thrown the other
way, the pressure on the piston Is relieved
and the water Is discharged into the tank
over there, through these pipes. Then the
elevator comes down by it's own weight
aud that OF the passengers
"Ihe valve il worked by the elevator
boy when he pulls the cord either way,
and il he should forget to pull the cord
the valve would act automatically, just
rs the valves In an engine do.
1.-THE wider the valve il opened, going
either way, the faster the car goes, up to
certain point, where, whatever might
happen, even supposing the valve to burst,
separate attachment, consisting OF an
independent cable, would stop the car by
the action Of what we call the safety gov
ernor. There you have the whole thing
in a nutshell"
And what II the wire rope which holds
the car should break'"
"The elevator would stop instantly, as
it would also II one Of the four ropes-for
there are four, not one-should even
stretch. The car would stop because by
reason OF simple device series OF
wedges would be thrown out and grip the
iron frame I'm which the elevator slides.
The heavier the load the harder the wedges
would hold"
In some elevators the big cylinder Is
visible above the floor III n vertical instead
of horizontal position, with the pulley
wheels scattered along at interval, on the
way up, as II TO give the passengers food
for reflection.
In some again there Is no water tank at
the top OF the building, the requisite pres
sure being obtained by pumping COM
pressed air. These are details which con-
Germ the elevator men only, and not the
general public IL In n splendid achieve
ment TO have mastered the main point OF
q aingle system.
One point which found interesting II
the question Of speed. How fast do these
elevators runS How many miles do they
cover day'
This merely depends upon tho number
Of pulley wheels You have attached TO your
piston rod. With six. seven or ten pairs
of pulley wheels, instead OF five pairs, the
elevators just under consideration would
run 80, Ga or lG0 feet farther for each
stroke Of the piston than they do at pres
ent.
The present rate II 500 feet n minute, 10
10 pairs OF pulleys would give 900 feet