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OPERATION
of C. C. Air Compressors
See Diagrammatic Views, Plates 1 and Z
When the high pressure steam piston 7 has nearly
completed its up stroke, the reversing valve plate 18
comes in contact with the shoulde.r on the reversing rod
21, forcing this rod to its uppermost position, carrying
with it reversing valve 22, the movement of which, in
turn, not only blanks passage
tn,
thereby cutting off
means of exhausting steam from chamber N on the face
of the large piston, but also opens passage n, filling this
with live steam from steam inlet passage a.
The pressure thus exerted on the face of the large piston
added to the pressure on the inner side of the small
1, is now greater than the pressure exerted against
the inner side of the large piston, and the piston valve
moves toward the left, or in the direction of chamber E.
The small end piston cylinder bush is provided with
elongated grooves. These grooves have been considered
for the sake of simplicity as combined into one groove,
p.
As the piston valve moves toward the left and uncovers
these grooves, live steam from chamber
A
by-passes to
chamber E back of the small end piston. At the instant
these grooves are cut off by the further movement of the
piston, port a leading to the exhaust is also blanked
which enables the small piston to. compress the steam
in chamber E, thus providing a high cushioning pressure.
This movement of the main valve piston admits steam,
through passage c, to the upper end of the high pressure
steam cylinder, starting the high pressure steam piston
18
OPERA'rTON
HI
on its downward stroke. All parts have now assumed the
position shown in Plate
l.
A direct communication is now established where
by live steam is supplied through passage a, chamber A',
and passage c to the upper end of the high pressure steam
cylinder,
downward the high pressure steam pis
ton 7 and low pressure air piston 9, which are rigidly
connected by a piston rod. The movement of the
valve to
left, as described above, has
g
to passage
f
through chamber F, thus permitting
steam in the lower end of the high pressure steam cyl
inder to
into the lower end of the low pressure
steam cylinder under piston 8. The latter cylinder being
of materially larger volume than the former, it will be
seen that the steam is thereby made to do its work ex
pansively in the low pressure steam cylinder. At the
same time
(a)
the low pressure air piston 9 is compressing
air in the lower end of the low pressure air cylinder
and forcing same through the intermediate valves
40 and passage
ttt
into the lower end of the high
pressure air cylinder under piston 10, and
(b)
air at atmospheric pressure is being drawn
into the upper end of the low pressure cylinder,
through the air strainer, upper inlet opening, and
past inlet valve 37.
It will be observed that the steam exhausted into the
lower end of the low pressure steam cylinder and the
low pressure air forced into the lower end of the
pressure air
sides of their
pIstons.
results in an
on the lower
The force thus exerted
,.,
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