Audubon County Republican. [volume] (Audubon, Audubon Co., Iowa) 1885-1894, 1891-11-12
All Kinds Plain and Fanog
JOB WORK.
Neatly and quickly executed b
EXPERIENCED WORKMEN
'QSTER AND COLOR WORK l SPECIALLY

teries and controlled by a signal lever
OF the pneumatic machine When air
is admitted TO the cylinder the piston
rod is forced up and the semaphore
blade Is lowered. When the air Is ex-
hausted the counterpoise on the sema-
pho, brings 1t to danger again.
although the operating mechan.
isms of the switch and signal are sepa-
rate, the switch and its signal are far
from being independent of each other.
Ky ingenious automatic devices, me.
chanical and electrical, II Is made i'm
possible Tor the oaerator to know
clear signal until after a switch Ii
moved and securely locked in the
proper position and each signal when
cleared automatically locks the leve,
operating II and prevents its being
used to release conflicting signals or
switches until II has been again placed
completely ut danger. These auto
matte devices are called the interloclS
ing mechanism.
"Over the pneumatic machine, in.
closed In glass ease, is a mini-tura
model Of the switching yard showing
every track, switch, frog and every
movable frog between Taylor street
and the station. Whcncvera switch Is
moved the model sw itch moves too, so
that the operator can tell ut a glance
the position OF affairs In the yard under
his charge
After the old.timer had satisfied his
mechanical curiosity by examining
every switch In the yard, the party
swarmed aboard switch engine and
rol ed on To the main track toward
Robey street To look into the electric
pneumatic block signaling system.
Electrician Ray called attention 10 n
high post on the right sido OF the track
having two large scmaphoro blades,
the upper one red, the lower green.
Il, Is Is II block signal, and the move
mcnt of the semaphOres Is controlled
entirely and automatically by the en-.
CINE, ear or hand ear passing over the
rails. A block IN tho section of track
between two such signals, the lengths
of blocks varying according To circum'
stances ana oSigoncies, Tho scmn-
phores are thrown Ia safety or clear,
that Is, the blades then point down nt
an ang,c of 90 degrees, by compressed
mir. Mike the semaphores on switch
signals, block somaphores stand nor
mully at clear Now, listlc electro
magnato operates the valve which i'd
mits or eNhuusts the compressed air
into the cylinder of the mechanism
which moves the scmuphores.
A current of electricity Is passed
around piece of soft iron, giving tho
property of magnetism 10 no iron only
80 long us the current il on. Now, the
steel rails of the track within block
arc tho conductors which carry tho
electric current, generated by common
gravity batteries, through the electro
magnet which operates the COM
pressed mir valve Of the signal mechan.
ism The rails are connected with
each other ut the splice ars by wire,
and. us the rails OF each block are on.
tircly insulated from those adjoining,
euch block has its Iwn circuit
Az the cur ent Is alwa-A on, the urmas
ture of the magnet operating the yalvo
nolds IL open, and the mir pressure
keeps the semaphorc blades at
safety" Hut suppose the electric
urrent is suddenly Switched off the
electro magnet; II loses its magnetism,
tho urmature no longer attracted to 10
rs drawn back By spring the valve
turns, shutting oil tho air pressure aud
the heavy counter weights ON the
semaphore causes II TO rise tn hori on
tai position, and so indicates danger.