TM 55-203
Figure 8-50. Emergency position.
very long trains at lower speeds without danger of a
feed groove is larger in the K-2 than In the K-1 triple
severe shock or break-in-two than is possible without
valve so as to maintain the proper rate of recharge to
this feature.
their respective auxiliary reservoirs in retarded release
position.
(3) Triple valve piston feed groove. At the
same time, the back of the triple piston is in contact with
g. Emergency Position. Quick action is caused by
the end of the slide valve bush, and, as these two
a sudden and considerable reduction in brake pipe
surfaces are ground to an accurate fit, the piston makes
pressure below that in the auxiliary reservoir, no matter
a tight "seal" on the end of the bush except at one point
how caused. This fall in brake pipe pressure causes the
where a feed groove (not shown in the dlagrammatics)
differences in pressure on the two sides of piston 4 to
is cut in the piston to allow air to pass around the end of
increase very rapidly, so that by the time the piston has
the slide valve bush into chamber R and the auxiliary
traveled to its full-service position, as already explained,
reservoir. This feed groove is much smaller than the
there is a sufficiently higher pressure on the auxiliary
standard feed groove t in the piston bush, so that when
reservoir side of the triple valve piston to cause it to
the triple valve piston is in retarded release position, the
compress the graduating spring 22, forcing back the
recharge of the auxiliary reservoir takes place much
stem and spring until the
more slowly than when it is in full-release position. This
piston seats firmly against the gasket, as shown
8-53
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