IMPROVEMENTS IN STEAM PUMPS
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by Milan Woodburn Hall and Albert
Elisha Hall at the Office of the Commissioners of Patents on the 2nd October
1883.
MILAN WOODBURN HALL and ALBERT ELISHA HALL, both of Plainfield, in the
County of Union, and State of New Jersey in the United States of America,
Mechanical Engineers; "IMPROVEMENTS IN STEAM PUMPS."
Our improved pump is duplex, employing two steam cylinders and two pump
cylinders, arranged side by side with the axes of the two pump cylinders in line
with the axes of the corresponding steam cylinders, and the two piston rods each
having a steam piston fixed on one end, and a pump plunger fixed upon the other.
The two steam cylinders are cast in one piece, the steam passages being cored out
in the tie portion between them. The two pump cylinders are likewise cast both
in one piece, which is cored out to form the necessary water passages. Above each
steam cylinder is a cylindrical valve chest, the ports of which communicate through
the steam passages with the other steam cylinder. The valve in each steam chest
consists of two small pistons mounted both on the same valve-stem, and the end of
this valve stem is connected to a rigid arm fixed to the piston rod beneath, so that
each piston moves with it the valve which controls the ports of the opposite cylinder
and the valve has the same stroke as the piston.
We will now more particularly describe the construction of the two steam
engines forming part of our improved pump, distinguishing them and their
cylinders, chests, valves, et cetera as right and left hand respectively. Each steam
cylinder is provided as usual with heads closing its ends, and with two ports near
each end, the space at each end beyond the port forming a steam cushion to stop
the movement of the piston easily. In order to introduce steam between the
piston when at the end of its stroke and the adjacent cylinder head, we employ a
supplementary port, opening into the cylinder close to the head and communicating.
through a branch-passage with the steam passage supplying the main port. A
check valve is interposed between this passage and the supplementary port in
such manner that no steam can escape from the cylinder through this port into the
passage, but steam may pass from the passage to the cylinder to start the piston,
by pressing the valve open. The valve is a disc seated on a perforated seat screwed
into a tapped orifice leading from the main steam passage to the branch passage
and a spring is arranged to press the disc to its seat.

page_text: The two steam passages leading from the ports in each cylinder pass through
the casting toward the other cylinder, and upward, terminating in openings in the
upper side of the casting over the other cylinder and communicating with two
cylinder ports in the valve chest which fits over that cylinder. These cylinder
ports in each valve chest are closer together than the two pistons forming the
valve, and between them the steam inlet port is placed. The two valve pistons are
arranged far enough apart, so that the inlet port shall never be closed, but shall
always communicate with the space between them, thus balancing the valve, the
only tendency of the pressure of steam being to press the valve pistons apart which
is resisted by their valve stem. When the valve is at mid-stroke in either steam
chest, say for example, the left hand one, both the cylinder ports are in communi-
cation with the steam space between the pistons so that live steam is conducted
through the communicating steam passages and is admitted to the right hand steam
cylinder on both sides of the piston, thereby balancing the piston while it is at
rest. When however the valve (moved by the other or left hand piston) has
advanced beyond mid-stroke to about three quarters stroke, one of its pistons
covers one of its cylinder ports for an instant and then when it uncovers it leaves
it in communication with the exhaust, there being an exhaust port at each end of
each valve chest. This permits the steam on the side of the right-hand steam
piston corresponding to the port uncovered to escape and the steam pressing upon
the other side of the piston starts it and propels it to the opposite end of the
cylinder. Shortly after this right hand piston has started the left hand piston
comes to the end of its stroke and stops, and remains stationary until the moving
piston moves its valve far enough to open to the exhaust the port through which
it has been receiving steam. Thus each piston actuates the valves and controls the
movement of the other so that while one is at mid-stroke, the other is always at
rest, and each commences to move just before the other comes to rest, thus causing
the pumping cylinders to act alternately and keep the column of water constantly
flowing without any cessation or interruption of the discharge. In order to effect
the correct operation of the engines with the arrangement of valves described it is
necessary to cross the steam passages leading from the cylinder ports to the
cylinder for one cylinder and leave those for the other cylinder uncrossed. We cross
the passage from the left hand cylinder to the right hand steam chest, but run
those from the right hand cylinder to the left hand steam chest direct without
crossing them. In the same casting we also form the inlet and exhaust passages,
the former passing under and beyond the latter in crossing from one steam chest to
the other, and communicating with the steam pipe through a short passage leading
to the rear. The exhaust pipe connects with the casting in front of the steam pipe,
and the passage from it leads to right and left and terminates in openings, each of
which coincides with a passage formed in the valve chest, which passes around to
the upper side thereof and along the top to each end thereof, where it communicates
with the interior of the valve chest. Our method of coring out all these ports
and passages in the three castings used, obviates all the couplings, joints and
external pipes heretofore employed for the steam passages in engines of this
character and greatly cheapens and simplifies the construction. To avoid the valve
pistons catching against the edges of the cylinder ports as they pass over them,
we do not cast the port openings in the valve chest but bore or drill round holes
through the bottom of the chest. These holes are two, three or more in number to
each port and are comparatively small.
We will now describe the pumps forming part of our invention. A long plunger
is fixed on the end of each piston rod, its length being twice the stroke plus the
width of the ring-packing employed. This ring-packing is arranged midway of
the ends of the plunger, the latter being made in halves, one half being slipped on
the rod against the shoulder, the packing rings being then applied and the other
half being slipped over the rod and fastened by screwing a nut on the end of the
rod, thereby confining the rings between the two halves of the plunger. The
cylinders in which the plungers work fit against the latter for a length equal to

page_text: the stroke plus the width of ring packing, so that at either extreme stroke one of
the halves of the plunger is wholly in and the other is wholly out of the cylinder.
The two cylinders are cast together and with the water passages and valve
chambers and the casting extends beyond the cylinders at both ends. The head on
each end of each cylinder is cupped to admit the projecting end of the plunger at
extreme stroke. The suction pipe is connected at the right or left side of the
cylinder casting and communicates with a water jacket surrounding both cylinders.
Above each cylinder the top of this jacket is a flat plate pierced with holes on
which are the inlet valves. The passages above this plate for the two cylindera
are separated from each other by a vertical partition, and another vertical partition
separates the passage leading to the front end of the cylinder from that leading to
the rear end thereof. The top of these passages is another flat plate pierced with
holes directly over and a little larger than the holes in the plate below. Both
these plates and the partitions mentioned are all parts of the cylinder casting and
on the top of this casting is fastened a top plate or cover forming the delivery
chamber from which the delivery pipe leads. The holes in the lower plate are
tapped, and flanged discs are screwed into them with gaskets under their flanges.
Each disc is perforated to admit the water through it and over each disc a rubber
valve is placed. The holes in the upper plate are dressed out, and similar
perforated flanged discs are fitted into them, being held down by passing a
shouldered pin down through the centre of each and screwing it into the disc
below until its shoulder bears down on the upper disc. These pins form guiding
stems for the valves. Rubber valves are also placed over the upper discs, and all
the valves are pressed against their seats by spiral springs. Valves and valve seats
thus constructed are simple, cheap, durable and easily accessible. The valves have
plenty of time to drop to their seats without shock or jar during the period of rest
of each engine.