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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47
(B) Emergency.
(a ) Elimination to the last degree of the time required to transmit
the application from one end of the train to the other and
of the time required to obtain maximum brake forces on
individual cars.
(b ) Degree of braking forces obtained and maintained.
97. For all types of brake control mechanism known at the present
time any desired increase in braking force for. . .
Service applications must be obtained by an increase in the brake
pipe pressure on account of the requirements of flexibility (service
brake). .
Emergency applications may be obtained by additional brake
cylinders or an increase in the reservoir volume for emergency applica-
tions only.
98 The ratio of brake cylinder volume to auxiliary reservoir
volume (service brake) is fixed by requirement under flexibility above.
The auxiliary reservoir volume therefore depends upon the diameter of
the brake cylinder and the predetermined and (assumed) fixed piston
travel.
99. A fixed leverage ratio (multiplication of total brake cylinder
forces to produce total force effective at the brake shoe) should be
established so that provision will be made for lost motion, defects, etc.,
in all parts involved. That is, sufficient clearance between brake shoes
and wheels should be insured. (Compensation for brake shoe wear
is a matter of maintenance, either manual or automatic.)
100. From the preceding it follows:
The apparatus employed in connection with the automatic air
brake should satisfy the above requirements.
Any additions to or modifications of this apparatus should conform
to and maintain unimpaired the basic principles above outlined.
101. The above will hold strictly true (within the narrow range of
variations permissible in any mechanical contrivance of this character)
for full service equalization with the apparatus in proper working order.
102 For graduated brake applications, short of equalization, the
results will vary within certain limits on account of circumstances
entirely beyond mechanical control.
103. Variations in resultant operations may be caused by the appa-
ratus not being in proper working order caused by lack of maintenance,
defective equipment or additional equipment inconsistent with the
existing apparatus conforming to basic principles outlined above.