Brake Tests
År: 1913
Forlag: Pensylvania Railroad Company
Sted: Altoona, Penna.
Sider: 401
A Report Of A Series Of Road Tests Of Brakes On Passanger Equipment Cars Made At Absecon, New Jersey, In 1913
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44. A chronograph, recording the distance of stop, time of stop,
deceleration of train, the brake cylinder pressure and the brake pipe
pressure, was located on car six (Par. 53). In connection with this
chronograph, a record was made of the action of the brake shoes with
respect to sparking (Chapter VII).
45. Indicators for measuring the slack action between the cars
were used at different points in the train (Fig. 16).
46. Specially designed apparatus was used to measure the pressure
delivered to the brake shoes during some of the tests, the object of
which was to determine the efficiency of the brake rigging (Par. 288).
47. Telephones were located in the first, third, sixth, ninth and
twelfth cars and greatly facilitated the issuing of instructions.
48. After each test measurements were taken of the total length
of the stop, and also the running piston travel on each car.
Brake Cylinder Indicator.
49. An automatic record of the brake cylinder pressure on each
car throughout a brake application was taken by a steam engine indi-
cator, having a large drum driven at constant speeds by a spring motor.
The indicator cards showed the brake cylinder pressure on a time base
line. In order that the time base on all cards might be directly com-
parative and not influenced by any inequality in the speed of the dif-
ferent motors, pencils arranged to record quarter second intervals on
each indicator card were connected in circuit through the entire train
to a master clock on the head car and to the trip cock on the locomotive
in such a way that the operation of the trip on the locomotive was
instantly recorded on every brake cylinder card. A photograph of
one of these instruments is shown in Fig. 8 and the wiring of the elec-
trical time circuit in Fig. 9.
Wheel Sliding Indicator.
50. On previous brake tests the sliding of wheels has been noted
by observers located on the platforms of each car. The usual pro-
cedure was for each observer to watch the wheels of the truck on his end
of the car and at the instant any pair of wheels picked up, a chain or
bar of iron was dropped from the platform to mark the point at which
the sliding started. The distance of the slide was then estimated.
The inefficiency of this method led to the design of an automatic re-
cording mechanism by means of which a single observer on each car
could obtain an autographic record of the revolutions of all the axles
on that car during the stop.