The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1898-02-07
PROGRESS OF THE WORLD.
New Things In Science, Invention, Industry and
Discovery.

! Action viii soon be taken by a joint
commission OF railroad officials for the
purpose of correcting an erroneous no
ton entertained by the general public
I concerning some railroad practices. The
ideas to be exploited are new and they
have come to be understood through the
I general application of the air brake.
When accidents, especially collisions,
have occurred heretofore, one OF the
questions always asked during the in
Vestigations which followed is Did the
engineer reverse his enginc2" Many
old engineers still believe that reversing
their engines would be the proper thing
TO do under many circumstances, and
! would so state it as their opinion in a
| court oe law. 1t is now a well estab-
lished fact that if an engineer on a
locomotive carrying air brakes on its
driving wheels was TO reverse his en-
CINE, the latter would actually forge
farther ahead than if the locomotive
was slowed up in the ordinary manner.
A train running 40 or so miles an hour
would go 30 per cent, or half as much
again, farther The reason is scientific
and interesting.
Every one knows that the steam en-
tering the cylinders drives the pistons.
If the locomotive is running fast and
the steam is suddenly cut Off the mo-
mentum of the engine will cause the
pistOns to so back and forth in the
cylinders. but now the air which PUSHES
in TO take the place of the steam acts
as n cushion upon which the piston
rods impinge and gradually lessons
their stroke. In the course of time
the Distons would stop working alto
gether. The wheels meantime are be-
ing acted upon by opposing forces-the
momentum Of the train to drive them
forward, and the effort of the pistons
to drive them bacl1W ard. This is par
ticularly the case il the steam is added
to drive the engine backward. The
wheels, therefore. being balanced be-
tween two forces. can do nothing but
slide, and once they start to do this the
engineer practically loses control of
them, and in consequence h and his
passengers may 20 over an open draw,
or smash up in a rear end collision The
point of the argument is based on the
fact that i a certain sense a sliding
wheel offers less friction to track than
a revolving Wheel. A train at rest is
harder to move than a train which has
already become started. In the same
way the point of a moving wheel hich
rests or the track is momentarily not
moving at all, although the top &c the
wheel IS moving twice as fast as the
hub. The purchase which this mo-
ment Of rest successfully eXerts on
the track is enormous. \ railroad track,
however much it may appear polished
to the naked eye, is, under the micro
scope, full of holes, and Inc correspond
ing but minute uneVenness of the
wheels fits into these holes so to speak, I
with q nicely that creates no end of
friction. Once the wheels slide this pur-
chase IS lost, and then it becomes a /
mere matter OF luck, as far as the i'm
mediate safety of the train is concern |
ed. The moral is that engineers should /
depend entirely on brakes, and to en-
force it some railroads have issued pos /
tive orders that engines must, under (
no circumstances, be reversed. With I
the public, however, this is not under ,
stood and in case of a court trial a /
smart lawyer might seek to convince a /
jury that the failure to reverse an en-
CINE would be responsible for an acct I
dent 1t is this curious possibility that /
the railroad men seek to avoid.