The Devils Lake world and inter-ocean. (Devils Lake, N.D.) 1915-1920, 1915-06-03
| [! ENGINES
Speed i Fast Locomotives IN ;' and ID
= How It Is Attained.
BIG WHEELS A NECESSITY.
But Equally Important Arc the Steam
;. Valves, the Crates In the Firsbox and
the Ability to Make Steam Rapidly.
Other Vital Factors.

the Ability to Mako Steam Rapidly.
Other Vital Factors.
The average person thinks that the
bigger the locomotive and the greater
the diameter of its driving wheels the
faster it will go. and in the popular
mind these are the only reasons one
engine can run faster" than another.
The locomotive, although one Of the
simplest and best known Of machines,
embodies. numerous devices not visible
to the eye Of the casual observer
which are most vital elements in its
efficiency and speed. For example,
much of the power Of the big express
engine depends upon the steam valves
and the CRATES in the f1rebox quite as
much as it does upon the mere big
ness of the driving wheels. At the
same time it is true that large wheels
in ordinary fast running are a con-
venience and in the very highest
speeds a necessity. 1t becomes neces-
sary, of course, to tighten the load as
the wheels are enlarged and increase
the speed. which introduces the Sec
ond phase of the problem-the CRATES
and heating surface.
Fast engines, to continue their work
for a long time at a stretch, must
make steam very rapidly. To accom-
plish this the heat Of the fire must
come in contact with the water at a
great many points. A large firebox
involves n crate Of large area to admit
air to the fire-a difficult matter since
but a small distance separates the
wheels, the width Of the firebox being
thus limited. while the length must
come within the limit to which the
fireman can throw his coal.
A third factor is the counterbalance.
the solid filling fixed between the
spokes of the driving wheels opposite
the connecting rods. This is to balance
the weight Of the cranks, parallel rods
and connections and, in addition, the
force on the wheels of the weight
Of the moving piston in the cylinder.
Lacking this balance the wheels would
roll too rapidly when the rods and con-
nections were moving downward and
wv OloW1S IACs WIZ luoN up-
ward, thus causing a jerky motion.
However, as the influence Of the
weight is varied by the centrifugal
force, which, in turn, IS greater or less
according as the speed is high or low.
1t happens that a countcrweight which
is suitable at n speed or forty or fifty
miles an hour produces an injurious
Sloo,,-S 80 Ia .,.la - n,,a
miles an hour.
It follows, therefore. that the weight
must be heavier than the rods and con-.
nections because a part Of its office is
to balance the piston and other parts
that slide horizontally and are unin-
fuenced by centrifugal force. AS the
! speed increases the downward motion
| Of the weight, as that part Of the
wheel rolls over to the front. makes
the wheel with its load press down
upon the rail with so much more force
than it does when the weight is O
ing upward on the other side that the
effect upon the rail is as If a heavy
blow were delivered upon it with a
hammer.
So to use an engine successfully ut
the highest speed it is necessary to
make the counterweight lighter than
would be correct for moderate speeds.
The light weights are not necessarily
dangerous at the lower speed, but their
use would aus unnecessary wear and
tear OF the engine and the track and
In some cases would even cause IN
pleasant jerks upon the passenger
cars. Fol this reason fast engines are
seldom built unless they can be used
In fast service all the time.
Properly proportional valve open
ings are absolutely essential to a fast
engine. These admit the steam to the
opposite ends Of the cylinder alter
nately, as the connecting rod moves
first forward and then backward, and
in a fast engine they must admit a
large volume of steam very quickly.
The valves must be moved 10 as first
to open one passage and close the 9th
er and then IS rapidly as possible close
the first and open the second.
It will be noticed by even the most
casual observer that the opening to
let the steam out of the cylinders into
the smokestack is several times as
large as that for admitting the "live"
steam. But even with this it requires
a considerable amount of power to
force the steam out with sufficient
quickness. This must be done in the
fraction of a second.
There are many engines that can get
steam into the cylinders quickly
enough and that are otherwise all
right for high speed, but which are
not so arranged to get rid Of this
steam which has been used and is
only in the way. 1t is this rapid ex-
pulsion Of the dead" steam that makes
the vigorous puffs at the top Of the
chimney that seem to indicate that
the locomotive is doing a tremendous
amount of work. 1t should be remem-
bered, however, that this noise is not
the result Of real work, but only Of