The Devils Lake world and inter-ocean. (Devils Lake, N.D.) 1915-1920, 1915-05-20
RAILWAY ENGINES
Speed of Fast Locomotives and
How It Is Attained.
BIG WHEELS A NECESSITY.

But Equally Important Are the Steam
Valves, the Crates In the Firebox and
the Ability to Make Steam Rapidly.
Other Vita! Factors.
The average person thinks that the
bigger the locomotive and the greater
the diameter Of its driving wheels the
faster 1t VIII 20, and i'll 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,
cmhodics numerous devices not visible
to the eye of the casual observer
which are most vital elements in its
efficiency ard speed. For example,
much Of the power Of the big express
engine depends upon the steam valves
and the CRATES in the fircboX quite rs
much us 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
%Henicnce. and in the very highest
speeds Il necessity. 1t becomes ncces-
sary, Of course, to tighten the load as
the wheels are enlarged and increase
the speed, which introduces the sec
ond phase Of the problcm-thc CRATES
and heating surface.
Fast engines. to continue their work
for Il 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. y large tirebox
involves a CRATE Of large area to admit
air to the tirc-a difficult matter since
but Il small distance separates the
wheels, the width of the tircbox being
thus limited. while the length must
come within the limit to which the
fireman can throw his coal.
\ third factor is the countcrbalancc,
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-
ncctions were moving downward and
too slowly when they We're moving up
ward. thus causing u icrky motion.
However, as the influence of the
weight is varied by the centrifugal
force, which, in turn. is greater or less
according rs the speed is high or low.
1t happens that Il CONFERENCE.-THE which
is suitable at a speed or forty or fifty
miles an hour produces an injurious
pound" On the rails at Seventy-iye
miles an hour.
1t follows. therefore. that the weight
must be heavier t!inn the rods and con
ncrtionS because Il part of its Office is
to balance the piston and other parts
that slide horizontally and are unin-
tlucncch by crnt"iru-al force. AS the
speed increases tll" Downward motion
of the weight. as tlil. part of the
wheel rolls over to- t!m front, makes |
the wheel Will, its lon1 press down
upon the rail with so much more force |
than it does when the weight is NOV
ing upward on the other side that the
eTcc upon the rail is as if u 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 countcrweight lighter than
would be correct for moderate speeds.
The light weights are not necessarily
n onrnro11c II thu. lpu-nr sr,,cJ ky,t fE1ir
use would cause unnecessary wear and
tear on the engine and the track and
in some cases would eyer causa.-,ln-
pleasant jerks upon the passenger
cars. For 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 so as first
to open n passage and close the 9TH
err and then rs rapidly as possible close
the first and open the second.
1t will be noticed by ever 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 Give"
steam. But ven with this it requires
a considerable amount Of power to
force the steam out with sufficient
G,1ickness. 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-
pufsion Of the dead" steam that makes
the vigorous puffs at the top of the
chimney that seem TO Indicate that