IMPROVEMENTS IN VALVES FOR DIRECT ACTING STEAM PUMPS
Year: 1879

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for the Invention of "IMPROVEMENTS IN
VALVES FOR DIRECT ACTING STEAM PUMPS." A communication from abroad
by George Washington Dixon, of Spring Lake, County of Ottawa, State of
Michigan, United States of America
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 30th June 1879.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent.
"IMPROVEMENTS IN VALVES FOR DIRECT ACTING STEAM PUMPS."
[A communication from abroad by George Washington Dixon, of Spring Lake,
County of Ottawa, State of Michigan, United States of America.]
The object of this Invention is to simplify the construction of valves for direct
acting steam pumps, and thereby reduce the first cost of such pumps and the
expense of repairs.
The Invention consists in a double seated slide valve, the same being substan-
tially the ordinary slide valve fitted within a case fixed in the steam chest, within
which case the valve slides, the space between the ends of the valve and the case
forming steam chambers into which the steam is admitted alternately to move the
slide valve by means of an auxiliary valve outside the case, but inside the steam
chest, operated by levers acted upon by the steam-piston. The valve seat has ports
arranged as usual, and upon it is fixed the case or boxing enclosing the slide valve
at the sides and ends closely at the former, but permitting it to have the proper
movement lengthwise. The slide valve is double seated, that is to say, it has a
projecting rim at the top which rests upon the upper edge of the case and is
sufficiently long to, in any position of the valve, form a cover for the case, separating
the space within it from the valve chest. The auxiliary valve is fitted in the steam
chest outside of the case or box, so as to slide and uncover one of two ports in the
valve seat that communicate from the outside to the inside of the caso at opposite
ends thereof. This valve is provided with a stem that projects downward into a
cavity in the valve seat communicating with the main exhaust port.
•

page_text: •
A lever is fulcrumed in each cylinder head in a suitable recess in such position
that each lever will be acted upon by the piston in its turn at the completion of
the stroke. These levers act on rods fitted in the upper part of the cylinder at
opposite sides of the stem of the auxiliary valve, whereby the valve is moved in
one direction or the other, according to the direction in which the piston is moving.
Each rod is fitted with a collar that acts as a packing to prevent passage of steam
through the holes in which the rods are placed.
The underside of the auxiliary valve is recessed to forin exhaust ports in
connection with that one of the ports connecting the steam chest with the interior
of the casing which it covers for the time being. When the valve is shifted by the 1
piston striking one of the levers one of these ports is covered by the valve, and the
steam enters by the other port and goes between the end of the slide valve and
the case, and forces the slide valve to the other end of the case, which action
changes the relative positions of the main ports. Upon the return stroke of the
piston the auxiliary valve is again shifted, so that the other port is uncovered and 1
the first port covered; the slide valve is thus moved in the opposite direction.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the
29th December 1879.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent. "IMPROVEMENTS IN VALVES FOR DIRECT ACTING STEAM PUMPS."
A communication from abroad by George Washington Dixon, of Spring Lake,
County of Ottawa, State of Michigan, United States of America.
The object of this Invention is to simplify the construction of valves for direct
acting steam pumps, and thereby reduce the first cost of such pumps and the
expense of repairs.
The Invention consists in a double seated slide valve, the same being substan-
tially the ordinary slide valve fitted within a case fixed in the valve chest, within
which case the valve slides, the space between the ends of the valve and the case
forming steam chambers into which the steam is admitted alternately to move the
slide valve. The admission of steam to these chambers is effected by means of an
auxiliary valve outside the case, but inside the valve chest, operated by means of
shifting levers acted upon by the piston head in the steam cylinder of the engine.
In the accompanying Drawing Figure 1 is a vertical longitudinal section of the
steam cylinder fitted with the improved valve mechanism; Figure 2 is a plan view
with the cover of the valve chest removed; Figure 3 is a cross section on line -
of Figure 1. Similar letters of reference indicate corresponding parts. a is the
cylinder; b, the valve chest; c is the slide valve moving upon a valve seat having
ports arranged as usual. Upon the valve seat a¹ is fixed the case or boxing d
enclosing the slide valve o at the sides and ends closely at the former, but permitting
it to have the proper movement lengthwise. The slide valve c is double seated,
that is to say, it has a projecting rim at the top which rests upon the upper edge
of case d, and is sufficiently long to, in any position of the valve c, form a cover
for the case d, separating the space within it from the valve chest. ƒ is the
auxiliary valve fitted in the valve chest outside of the case or box d, so as to slide
and uncover one of two ports g, gl, that are formed in the valve seat, and commu-
nicate from the outside to the inside of case d at opposite ends thereof. This
valve fis provided with a stem h, Figure 4, that projects downward into a cavity i
in the valve seat, which cavity communicates with the main exhaust port k.
In each cylinder cover in a suitable recess is fulcrumed a shifting lever or in
such position that each lever will be acted upon by the piston in its turn at the
completion of the stroke. These levers act on rods m, m', fitted in the upper part
of the cylinder a at opposite sides of the stem h of the auxiliary valve f, whereby
the valve is moved in one direction or the other, according to the direction in
which the piston is moving. Each rod m is fitted with a collar n that acts as a
packing to prevent passage of steam through the holes in which the rods are placed.
The underside of the auxiliary valve f is recessed, as seen at o, Figure 4, to form
exhaust ports in connection with that one of the ports g, g', which it covers for the
time being. When the valve ƒ is shifted by the piston striking upon lover &, as
described, port g' is covered by f; the steam enters by the other port g and goes
between the end of the slide valve o and the case d, and forces the slide valve o to
the other end of box d, which action changes the relative positions of the main
ports. Upon the return stroke of the piston valve f is again shifted, the port g' is
uncovered, and the port 9 covered; the slide valve o is thus moved in the opposite
direction. As soon as valve f is shifted the recess o in its underside coincides with
port g' and permits the escape of the steam from that end of box d.
The mechanism described has but few parts, and those are of simple construction,
such as can be repaired by any mechanic familiar with the ordinary valve mechanism
of steam engines.

page_text: Having described the nature of the said Invention, and the manner of per-
forming the same, I declare that what I claim as the Invention to be protected
by the herein before in part recited Letters Patent is,―
1st. In combination with the cylinder and valve chest, having ports substantially
as described and shown, the valve c, case d, and valve f, the valve f being shifted
by the movement of the piston head through positive connections, substantially as
described and shown.
. 2nd. In combination with the valve mechanism of engines, wherein the main
valve is shifted by the pressure of steam upon the valve, the auxiliary valve f,
roda m, and levers 2, constructed and arranged for operation substantially as
described and shown.
3rd. In combination with a cylinder and valve chest, having ports substantially
as described and shown, the case d, double seated valve c, valve f, rods m, and
shifting levers, combined, arranged, and operating substantially as described and
shown, and for the purposes set forth.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Twenty seventh day of December, in the year of
our Lord One thousand eight hundred and seventy nine.