The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1917-05-03


descent of mountain grades; and
when one stops to think that the en-
gineer at all times must have absol-
ute control of the last fractional kill
owatt of his power in order to regu-
late to certainty the train speed,
then one begins to realize that the
electric locomotive is not simply a
magnified trolley car.
Again it must be remembered that
these locomotives are driven by cur
rent of 5000 volts potential. the highes
direct voltage employed in railway
work anywhere in the world, and that
this is more than five times the cleo
trical pressure used in ordinary street
railway service In the lighter trac-
ton work the low tension currents
employed may be handled directly In
the controller by means of compare
lively few resistance coils and a
small number of hand operated
switches.
in the case of this 5000 volt cur
rent, however such control Is impos-
sible; and other associate features
calling for the highest of engineering
skill, have been devised In order tC
make 1t possible for the man at the
lever to dominate this tremendous
force"
Regenerating Brakes.
No feature of this entire system il
more interesting than that which has
to do with the conservation of ener-
gy and, therefore. the reduction oil
running charges. This is the social
ed system of regenerative braking.
| The engineers responsible for the
electrification of this transcontinenta
| line knew that it was possible theor-
etically so to handle an electric loco
motive that a portion of the energy
consumed in climbing gradien,
might be regained, regenerated by
means of gravity, when descending the
slope But never had the principle OF
regenerative braking been applied tc
most severe conditions of actual heavy
service. 1t was necessary for the en-.
gineers step by step to work out ways
and means to this end.
The following word picture of how
the trick Ia done has been drawn by
one of the engineers responsible for
the achievement: The train gathers
momentum as 1t coasts down the in
cline Gently the speed slackens; the
motors, not the brakes, which are not
needed are asserting their perfect
control of this mighty bulk.
1.-The gradient becomes sharper, but
speed is not accelerated Instead as
the engineer scans the dial of his am
meter he sees the trembling pointer
slowly reverse it's motion, creeping
point by point in the direction oppo-
site to that indicating consumption OF
power.
1.-The motors for the nonce turned
generators, are actually giving back
current to the transmission line, and
thus helping some other train up the
grade. The descending train is in eff
feet a producer instead of consum-
er of electrical energy"
Manfestly this is utterly unlike
anything that is possible where steam
| locomotives are emplOyed
Sources Of Power.
| And now for the primary source o.
Rocky Mountain divisions of the Chi.
cago Milwaukee & st. Paul railway
Here we have one of the high spots ii
our tardy development of the natura
resources of the United States.
The railway company obtains the
necessary propulsive energy from the
Montana Power company, which de.
livers current at seven points to the
transmission system between Avery
and Harlowton. The power plants Of
the Great Falls hydro electric system
the greatest natural power site in
Montana and one of the largest in the
country, are located on the upper
reaches of the Missouri river, where
within distance of eight miles the
waters have a drop of 400 feet. Re-
membering that an electrical kilowatt
hour is equivalent mechanically to
1.34 horse power, the importance OF
the Montana Power company's great
conservation enterprise can be more
fully understood when it Is realized
that it already operates to capacity
Of $3.50 kilowatts and has upward
of $4,000 kilowatts under develop
ment
A hint of the economics effected
through the abandonment of steam
haulage and the substitution of cleo
trio traction in the case of the Chi
cago, Milwaukee & ST. Paul railway
can be inferred from what was actual
ly achieved about three years ago on
the Butte, Anaconda and Pacific rail-
way in the same region. After some
investigation It was de-
cided to embark upon an expenditure
OF sl,20l, 600 in electrifying 30 miles
of track and in substituting II cleo
trio locomotive units for 22 steam To-