IMPROVE- MENTS IN OR RELATING TO BALANCED SLIDE VALVES
Year: 1885

page_text: We WILLIAM ROWNTREE, of 9 Havelock Square Sheffield Secretary and Cashier,
and GEORGE TEMPLE of 67 Fowler Street, Pyebank, Sheffield, in the County of
York, Engineer do hereby declare the nature of our said invention for "IMPROVE-
MENTS IN OR RELATING TO BALANCED SLIDE VALVES" to be as follows:-
This invention has for its object a simple arrangement of balanced slide valve
applicable without serious alteration to existing engines. It is an improvement
upon the invention described in Provisional Application 13619 of last year.
The valve is preferably made with the flanges internal instead of external so as
to enable the valve to be made with a simple cubic rectangular outside contour,
and so that the area of its back surface in one plane shall be equal to its front
surface including ports. The valve rod is attached to it in any convenient manner.
The back of the valve like the face is planed to a true surface, but if desirable the
central portion can be hollowed out to lessen friction, leaving a portion of plane
surface all round. I prefer however a plane surface throughout. At the back of
the valve I place a plate hereafter called the shield plate, planed to a smooth
polished surface on the side next to the valve. This plate is made sufficiently long
and wide to entirely cover the end of the valve throughout its travel, but is not so
large as to fill the full cross section of the steam chest, but has spaces at the sides
and ends to allow steam to pass round it. A stud, having a flat cylindrical head
is fitted into a socket plate screwed to the shield plate or forming a part of said
plate with side opening in such case to allow of stud head being slid in sideways.
This stud is screwed at the free end and passes through the ordinary steam chest
proper with a loose fit. A second chamber rather larger in area than the valve
closed by a diaphragm plate is attached to the cylinder cover, but is open to the
steam chest proper by connecting holes. The diaphragm plate is formed of thin
sheet steel or other strong elastic material supported on each side by stout plates
so as to leave only a small part clear for flexibility. The main stud is screwed
through these plates holding them tightly and capable of being regulated, so that
there shall be a slight strain tending to press the shield plate against the back of
the valve when the steam is off. Other screws hold the diaphragm and its two
plates tightly compressed together, and screws passing through a ring hold the
diaphragin to the casing by means of nuts. Regulating studs are useful to prevent
IDmins G27

page_text: the plate from flapping back against the lid of the steam chest proper, and I some-
times add a spring coiled round the main stud to assist in keeping the shield plate
against the valve back.
In erecting and setting the apparatus, the nut on the main stud being slack, the
spring presses the shield plate against the valve and holds it in its true position.
The main stud is now adjusted in the diaphragm plates till a slight pressure is
brought on the valve forcing it against the scat. The check nut is now tightened
up. The steam is turned on and the valve tried by hand, when if it be too tight
or two slack the check nut is loosened and the main screw adjusted. It will be
obvious that if desired the apparatus can be still further simplified by doing away
with the steam chest lid and allowing the diaphragm to act as steam chest cover
solely. The use of the steam chest lid being little more than a guide for the main
stud and a holding ground for the regulating studs, if it were dispensed with these
latter studs could be fixed in the diaphragm instead.
WM P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, and
323, High Holborn, London,
Patent Agents for the Applicants.

page_text: COMPLETE
SPECIFICATION,
We WILLIAM ROWNTREE of 9 Havelock Square Sheffield Secretary and Cashier
and GEORGE TEMPLE of 67 Fowler Street Pyebank Sheffield in the County of
York Engineer do hereby declare the nature of our said invention for "IMPROVE-
MENTS IN OR RELATING TO BALANCED SLIDE VALVES and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement:-
"
This invention has for its object a simple arrangement of balanced slide valve
applicable without serious alteration to existing engines. It is an improvement
upon the invention described in Provisional Application 13619 of last year.
The invention is best described by aid of the accompanying drawings in which
Figure 1 is a section and Figure 2 a plan of said invention.
The valve A is preferably made with the flanges internal instead of external, so
as to enable the valve to be made with a simple cubic rectangular outside contour,
and so that the area of its back surface in one plane shall be equal to its front
surface including ports. The valve rod is attached to it in any convenient manner.
The back of the valve like the face is planed to a true surface. At the back of the
valve we place a plate B planed to a smooth polished surface on the side next to
the valve. This plate is made sufficiently long and wide to entirely cover the end
of the valve throughout its travel, but is not so large as to fill the full cross section
of the steam chest, but has spaces at the sides and ends to allow steam to pass
round it. A stud C having a flat cylindrical head is fitted into a socket plate d
screwed to the shield plate B, or forming a part of said plate with side opening, in
such case to allow of stud head being slid in sideways. This stud is screwed at
the free end and passes through the ordinary steam chest proper with a loose
fit. A second chamber D rather less in area than the valve, closed by a diaphragm
plate E is attached to the steam chest cover, but is open to the steam chest proper
by connecting holes F. The diaphragm plate is formed of thin sheet steel or
other strong elastic material, such as phosphor bronze plate, supported on each side
by stout plates G H so as to leave only a small part clear for flexibility. The
main stud is screwed through these plates or one of them G (as shown) holding
them tightly and capable of being regulated so that there shall be a slight strain
tending to press the shield plate B, against the back of the valve A when the
steam is off. Other screws II hold the diaphragm and its two plates tightly
compressed together, and screws J J passing through a ring K. hold the diaphragm
to the casing of chamber D by means of nuts. Regulating studs L are useful to
prevent the plate from flapping back against the lid of the steam chest, proper.
The main stud C is now adjusted in the diaphragm plates till a slight pressure is
brought on the valve forcing against the seat. The check nut is now tightened
up. The steam is turned on and the valve tried by hand, when if it be too tight
or too slack the check nut is loosened and the main screw adjusted. It will be
obvious that if desired the apparatus can be still further simplified by doing away
with the steam chest lid and allowing the diaphragm to act as steam chest cover
solely. The use of the dividing plate between the two chambers being little more
than a guide for the main stud and a holding ground for the regulating studs, if it
were dispensed with these latter studs could be fixed in the diaphragm instead,

page_text: In the foregoing description we have described the entire invention as well as
our new improvements. In the original invention a block of rubber was used as a
buffer, this however was found not to answer as it is affected by heat, and in a
short time receives a permanent set and begins to disintegrate, and we have found
a thin diaphragm plate of steel or phosphor bronze much the best, if of steel it
must be well painted or protected, but where thin flexible elastic phosphor bronze
plates such as are used for Coe's marine condensor valves, can be procured, these
will probably be found most effective. Another point in the first invention which
we found a very serious defect was that as the position of the plate B had to be
regulated by screwing inside the steam space, it could only be adjusted and
regulated when the steam was off, but could only be tested to see if it would
answer when the steam was on. A long series of trials were therefore required
to get it right and even then the rubber altering in its properties with heat, soon
requires re-adjustment. In the present invention by screwing the stud C through
the diaphragm plates and locking it with a nut on the outside only, the position of
plate B can be regulated with the utmost nicety at any time while the engine is
running, or while the steam is on-a very important point.
"
Having now particularly described and ascertained the nature of our said
Invention, and in what manner the same is to be performed, we would state that
we are well aware that blow through valves, that is, valves having a port on both
sides have been proposed in times past as balanced slide valves, and that it has
been proposed to provide them with a second adjustable valve face at back, but
such valves are found very liable to leak between the valve and back plate unless
a very heavy pressure be brought to bear on them which neutralises their value,
and we make no claim for such, but we declare that what we claim as our
invention is
1st. In combination with a valve and back plate, such as described, a thin
elastic metal diaphragm linked to the back plate and exposed to the steam pressure
so as to counterbalance the requisite amount of steam pressure on the back plate,
substantially as described.
2nd. The combination of the back plate with the regulating stud head C firmly
held in the same against a direct pull, but free to turn therein, whereby the stud
can be turned and regulated at pleasure, substantially as and for the purposes
described.
3rd. The combination of back plate B, stud C free to turn therein, and screwed
through or held in diaphragm plate or its appurtenances in such manner that
without taking off the diaphragm plate or steam chest cover or getting otherwise
to the inside the relative distance between the back plate B and the diaphragm
can be changed or regulated at pleasure.
4th. The improved apparatus for relieving the back of a slide valve from
pressure, substantially as herein described.
WP. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, and
323, High Holborn, London,
Patent Agents for the Applicants.