New-York tribune., 1907-07-07
DTN1MOUETER CAR.
Use Made of 1t IN SoIving Railzcay
Problems.

How many 100-ton coal cars ought the heaviest
locomotive to haul on cold day over a certain
division of a road? If the coal were In smaller
cars would it be easier or harder to move it?
These questions typical of hundreds which
come up before the operating department of
railroad. and efficient handling of traffic is
largely dependent upon their solution.
Increasing the number of tracks is way of
meeting the growth of traffic, but this takes
time. and while ii Is going the present tracks
must be worked 10 the limit. Locomotives of
enormous capacity must be built and run at their
most productive speed, drawing cars for freight
Of such proportions that every ton is handled
with the least expenditure of energy and on
schedules which involve the fewest train stops.
In order to determine with certainty and
curacy the force required to pull trains of cars
over various sections of the road. and more par
ticularly TO find out which classes of cars pulled
exceptionally hard easily. the Pennsylvania
Railroad has built a special which contains
a huge scale. constructed that it actually
weighs the pull eXerted by the locomotive in
drawing the train. This dynamOmeter car, as 1t
Is called. is not the first OF it's kind, but il is
unique In that it IS big enough and accurate
enough and complete enough to do we'll all the
work put upon it, At first thought it might
seem that machine designed to do only one
thng-to measure the pull a coupling or
drawbar-miEht have very limited application;
but consider the multitude Of uses for n two-foot
rule The car has proved very useful. II is
coupled into train just back of the tender in
front of the first car. In measuring the pull of
the locomotive it really does three things: 1t
measures the capacity of the locomotive. il de-
termines the with which various classes of
cars are handled and shows the effect OF grades
and curves on the pull required TO move the
train.
\ train carrying two thousand tons of coal.
loaded in large steel each holding fifty
tons VIII be drawn over a certain portion of the
road and an accurate record kept Of the pull de-
livered by the locomotive. Another train with
the amount of coal loaded in smaller
wooden cars will be pulled over the same track.
A comparison of results will indicate whether
il takes more or less pull ton of coal To move
IL in the large cars, and the gain Of one form
over another will be an indication of how much
money II Is advisable to spend in getting the
cars of the particular type which showed the
best results in the test.
The effect of cold weather upon the starting
and hauling capacity OF locomotives. well as
upon the pull required to draw the cars Is also
thoroughly Investigated.
1t sometimes happens that a curve is located
upon up grade. The train probably has hard
work on the grade anyway. and when 1t comes
10 the curve il slows down more. To avoid this
the grade curves IS usually reduced SO that
speed can be kept constant. BY means OF the
dynamometer 1t Is possible % find out how
much 10 reduce the grade TO compensate exactly
for the curve. In this way every class Of roll
ing stock is tested. with the idea OF eventually
securing those types which make II possible 10
transport over the road the greatest volume of
traffic. and relieve the stress brought about by
+ the enormous growth OF business.
The dynamonster car is equipped with berths
accommodating eight men. who accompany the
car and make all of the necessary readings for
test. The scale which weighs the pull operates
on the same principle as spring balance. but
is exceedingly delicate and enormously powerful
The machine is arranged that most of its
readings are automatically recorded. and AZ the
end Of 4 its complete written history n
available. In addition TO the drawbar pull. the
speed at which the train is travelling. the posi-
tons OF levers and steam pressure of the engine
together with the mile posts along the way. are