Pumps

3878

Pumps

draws water in through one set of suction
valves and discharge? through the discharge
valves at the opposite end of the water cyl-
inder. On its stroke to the left, it draws in
water through the other set of suction valves
and forces water out through the discharge
valves at the other end.

A duplex pump, one torm of which is
shown in Fig. 4, is made up of the elements

mine shafts, filling storage tanks on the roof?
of buildings, pumping oil, acid, or dirty or
gritty water, and scores of other special forms
of service.

Power Pumps.—A power pump is one in
which the water piston or plunger is given a
reciprocating motion through the agency of
a crank and a connecting-rod or its equiva-
lent. It may be simple, duplex, or triplex, ac-

Fig. 3. Simplex Direct-Acting Steam Pump.

of two simplex pumps placed side by side and
interconnected in such a way that the motion
of the piston rod of one half of the pump
gives motion to the valve gear of the other
half. With this construction il. is impossible
for the pump to stop at dead center.

Fig. 4. Fairbanks-Morse Duplex Direct"
Acting Pump.

Direct-acting steam pumps arc; used for a
large number of purposes, as, for example,
feeding steam boilers, supplying water to hy-
draulic elevators, removing rondensatu from
steam condensers, furnishing water at high
pressure to fire systems, removing water from

cording to the number of cranks used, and
the motive power may be furnished by steam
engine, gasoline engine, water wheel, electric
motor, or belt from a countershaft; also, the
pump may be either horizontal or vertical, In
Fig. 5 is shown a horizontal duplex power
pump. A belt on the tight and loose pulleys
gives motion to the shaft carrying the pinion
that meshes with the large gearwheel. The
gear is keyed to the end of the crunk shaft,
which has two cranks. To each crank is at-
tached a connecting-rod that leads to a cross-
head fastened to the rod to which the water
piston is secured. The cranks are 0.0 degrees
Apart and thus the discharge of the pump is
practically continuous.

Centrifugal Pumps.—A type of pump that
has been greatly improved in recent years,
both in efficiency and in height of lift, is the
centrifugal pump, so culled because centri-
fugal force is an important factor in its op-
eration. Briefly, it consists of a disk or wheel
having vanes and rotating inside a casing.
Water is admitted to the center of the rotat-
ing part, which is called the impeller, and un-
der the effect of centrifugal force the water is
thrown outward along the vanes, being fin-