===============================+=============================
BOILER PUMP. | DBLE.-ACTING FORCE PUMP.
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Diam. | Suc. and | Gal. per| Diam. | Suc. and | Gal. per
cyl. | dis. | stroke | cyl. | dis. | rev.
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2-1/2 in.| 1-1/4 in. | 1—8 | 3 in.| 1-1/2 in.| 2—5
2-1/2 „ | 1-1/4 „ | 1—8 | 4 „ | 2 „ | 4—5
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In Fig. 207 is shown a double acting power pump used principally for
feeding boilers but may be employed for any purpose in forcing water
or other liquids against pressure. This pump is double acting, is made
with four _check valves_, as shown in engraving, and will draw water
through 25 feet of suction pipe. On a high lift like the foregoing a
foot valve (as shown at D in Fig. 204) should be used.
[Illustration: FIG. 207.]
The form of valves used in this type of pump are the regular commercial
check valves, made of steam-metal, extra heavy; the valve proper is of
the _wing_ pattern as shown in the small cuts. There are four of these
wings on each valve, at right angles to one another forming a cross
with arms of equal lengths.
[Illustration: STRAIGHT WINGS.]
[Illustration: SPIRAL WINGS.]
The seat of the valve has an angle of 45° to which the valve is
adjusted. A part of this valve projects above the top and has a slot,
shown by the dotted line in it to receive the edge of a screw-driver,
held in a bit stock to grind the valve seat in refitting. The lift of
the valve is regulated by the distance between the top of the stem and
the bottom of the covering nut or cap.
In hydraulic pumps it is found to be good practice to give the wings of
these valves a twist, or pitch, so that the water in passing through
will cause the valve to rotate and fall in a new position every time it
comes in contact with the seat.
Fig. 208 represents a very compact design of _double acting low service
belt driven pump_. The water cylinder is bored and has a piston fitted
to it; both ends of this cylinder are covered with “heads,” one of
which has a stuffing box through which the piston operates; the outer
end of this piston rod is fitted to a slotted yoke which slides upon a
guide at the bottom.
This mechanism, just described, takes the place of a pitman connection
and occupies very much less space. The crank shaft is supported at each
end in pillow blocks and is driven by a belt having a tight and loose
pulley; larger sizes are geared. Access to the two sets of valves can
be had by slacking up four nuts upon the long belts, two of which are
shown in the engraving. The broad base secures great stability for this
size pump.
[Illustration: FIG. 208.]
[Illustration: FIG. 209.]
[Illustration: FIG. 210.]
Fig. 209 exhibits two _single acting plunger pumps_ actuated by one
shaft having a crank upon each end with crank pins opposite to one
another. This shaft is supported on the top of two pillars which form
a part of the solid cast iron frame. The boxes are babbited. The crank
shaft has a cast iron spur gear keyed to it and meshes into a pinion
upon the pulley shaft. The teeth are cut to insure smooth and quiet
running. The power is transmitted through a belt upon a tight and loose
pulley. Each pump is secured to the frame by four bolts. The lower
end of the pitman has an arrangement to take up the wear by means of
two set screws with lock-nuts as shown in the figure on the top of
each plunger. This pump is largely used as a boiler feed pump. These
pumps can be used separately or together and with single or compound
connections.
_Duplex Power Pump._ This engraving, Fig. 210, shows a special
boiler feed pump having ball valves, as shown in section, and which
is also intended for use in pulp mills and in other places where it
is necessary to pump sandy or muddy water, or chemicals, soap and
other heavy bodied liquids. These pumps have composition ball valves,
composition plungers and composition lined cylinders and glands.
The two barrels or cylinders of this pump are brought together so as to
occupy as little space as possible. Instead of cranks eccentrics are
used having very large wearing surfaces. Each pitman has a ball at its
lower extremity forming a “ball and socket” joint, which is adjustable
to compensate for wear. All the bearings are Babbitted and like the
last pump described the gears have cut teeth. It is belt driven.
_If there are two cranks as in the duplex power pump_ they are placed
opposite to one another or 180° apart, the circle described by the
crank-pin containing 360 degrees. _In the triplex pump_ this circle is
divided into three equal parts of 120° each which is represented by the
position of the cranks; _a quadruplex_ or two duplex pumps attached to
the same shaft the cranks will be 90° apart. This arrangement effects a
uniform distribution of load on the crank shaft and one of the pumps is
continuously discharging at its maximum capacity.
This duplex _power_ pump should not be confounded with the “Duplex
Pump” so called. The latter has two steam cylinders and two water
cylinders and is double acting while the former is single acting.
The successful operation and durability of these, as of all power
pumps, depends largely upon the judicious selection and application
of a proper _packing to the stuffing boxes_. As for example, plaited
flax dipped in a mixture of warm graphite and tallow, braided rawhide,
Selden’s packing, etc., have proved by long service to have a _low
co-efficient of friction_ and are not liable to cut the plungers.
_The triplex power gang pump_ is shown in Fig. 211. The engraving
represents two triplex pumps bolted to one bed, and having an extended
pulley shaft with pinions near each end to drive all of the pumps.
[Illustration: FIG. 211.]