Engineering Wonders of the World
Volume I
År: 1945
Serie: Engineering Wonders of the World
Sider: 448
UDK: 600 Eng -gl.
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A RAILWAY DYNAMOMETER CAR. 255
contact with the horizontal table, it will be
caused to revolve when in any other position
than the centre. It will be seen that the
number of revolutions of the small wheel de-
pends on two factors—namely, the number of
revolutions of the horizontal table, which is
proportional to the number of feet moved by
the train, and its distance from the centre of
the horizontal table, which is proportional to
the pull on the drawbar ; its revolutions are
therefore proportional to the foot-pounds of
work given out at the drawbar. The revolu-
tions of this wheel are recorded on the travel-
ling roll of paper by the aid of one of the
pens previously mentioned.
The total work is also registered by elec-
trical means on a train of dials.
So far the tractive effort only has been
considered. To give value to “ work ” records
certain particulars about the locomotive’s be-
haviour must be known. An indicator records
continuously the pressure in the steam chest.
The last is connected with the indicator by
a pipe, which transmits the pressure to a
cylinder operating a pencil that marks a
slowly rotating drum. Other apparatus
records furnace heat, the draught pressure
in the smoke-box, the position of the re-
versing lever, the direction and velocity of
the wind. By co-ordinating all the data
thus obtained, and comparing the fuel and
water consumption with the work given out,
the total efficiency due to any change of
design can be estimated.
For brake tests a frame supporting three
indicators can be fixed on the existing in-
strument table, and the pressures in the
brake cylinder, auxiliary reservoir, and train
Fig. 4.—DRAWBAR SPRING BEING TESTED BY
WEIGHTING IN THE WORKSHOPS.
pipes thus recorded. The clar is also of use
for finding the sighting point of a signal, or
the distance between two points, an electro-
magnetic pen controlled by the observer
marking the positions on a travelling roll of
paper. In a similar way, with the aid of
the clock beating two seconds, the time lost
by speed limitations can also be determined.
In short, any information likely to be of value
in connection with locomotives and rolling-
stock may be obtained with this car.
■MM