_Answer._--There are various sizes, ranging from a 1/4-inch to 4 inches
in the diameter of the plunger or piston, as it is sometimes called; the
larger size would be constructed in this manner; the barrel of the pump
is 3 feet long, and on its top, and in line with it, and in the same
casting, an air chamber is situate into which water and air enter at
every suction of plunger, and serve as a buffer or cushion in the
delivery stroke. The spindle of the plunger is connected to the piston
of the steam engine by a hole and stuffing box in the cylinder cover,
and a connecting crosshead secures the spindle of the plunger and the
extra piston, so that would bring the crank of the engine, the
connecting rod, piston, extra piston, and plunger all in a straight
line, and a direct stroke. About 6 inches of the plunger is occupied by
the packing at the outer end; a solid ring of iron an inch wide, and an
inch high, and securely pinned to the plunger, has a leather cup pushed
on to it, then a loose ring is slid up against the back of the leather
cup and another cup, and another ring, until the space for the packing
is filled up; then a nut is screwed up behind these which brings cups
and rings tightly together, and a jam-nut with a split-pin going through
nut and spindle and opened wide enough to clear the sides of the barrel,
and the hydraulic pump is ready for work.
35. _Question._--How is a hydraulic accumulator constructed, and why is
it necessary?
_Answer._--By having an accumulator, a lift, crane, or press, works
smoothly, as there is a steady and smooth supply of the power; whereas
without it, the lift, crane, or press, would work in jerks or jumps;
with every stroke of the pumps there would be a jerk; it would be an
intermittent not a continual power. The accumulator consists of a
cylinder of cast iron about 9 feet in height, 4 feet outside diameter
and 3 feet internal diameter; it rests on massive oaken timbers about 4
feet from the ground; inside the cylinder is a ram 9 feet high, also 2
feet outside measurement, and 12 inches diameter inside; it is
lathe-turned, smooth and bright; four slabs of cast iron, each a quarter
of the circumference of the base of the cylinder, are placed over four
steel bolts that have to support the dead weight, each bolt being about
12 feet high, 4 inches in diameter, with square necks and flat heads,
and a hole in each slab to receive the bolts; the flat heads of the
bolts are to facilitate the accumulator resting level on the oaken
timbers; the slabs would be 2 tons each. On the slabs are fixed small
segments all round and round the base of the cylinder until the required
number (perhaps 150) is placed one on top of the other, each segment
weighing 2 cwt.; then the crosshead is placed over the top tier, and
having a hole in each of its four arms it is entered on the bolts which
have a screw-thread; the nuts are put on and screwed up tightly, and the
accumulator is erected.