AN IMPROVED BALANCED SLIDE-VALVE
Year: 1881

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of "AN IMPROVED
BALANCED SLIDE-VALVE." A communication from abroad by William Bright
Turman, of Waldron, in the County of Scott, State of Arkansas, United States
of Amarion
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 8th November 1881.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. AN IMPROVED BALANCED SLIDE VALVE." [A com-
munication from abroad by William Bright Turman, of Waldron, in the County of
Scott, State of Arkansas, United States of America.]
"
The object of this Invention is to reduce the friction of the valve and conse-
quently the power required to move it, and also to permit of a simultaneous steam
supply and exhaust.
The Invention consists in the combination with the steam chest provided with
supply and exhaust ports, guide strips, and adjustable packing strips, of a valve
provided with an entrance port, interior steam chamber, exhaust ports, an opening
between the exhaust ports and projections on its top and one side.
The steam supply port is on one side of the steam chest and the exhaust port
on the opposite side, and on the inside of its top or cover along the central line
thereof is fixed a box in which is a packing strip that is adjusted by set screws and
half elliptic springs against the valve to regulate the pressure of the latter on its
seat, and on the inside of the exhaust side of the steam chest another packing strip
is adjustably held in braces aud is pressed by set screws and half elliptic springs
against the valve to hold the latter with any desired pressure against the steam
supply side of the said chest to prevent leakage thereabouts with the said chest.
The valve has in one side a port for the entrance of steam, communicating with
its hollow interior, and this interior chamber terminates at each end in a port in
the valve face. Between these ports the under face of the valve is cut away to

page_text: reduce the friction surface upon the valve seat and to permit the escape of exhaust
steam from the steam cylinder when used on the common three port valve seat.
On the top and one side of the valve are formed longitudinal ridges for the
packing bars or strips to bear against.
Steam is admitted through the valve chest port into the valve port, thence out
of tlie valve through one of its ports into the engine cylinder, by which the piston
is driven to the opposite end of the cylinder, and by the action of the eccentric tho
valve is so moved as to arrive at the same end at or near the same time with the
piston, thereby opening the port in the other end of the cylinder to permit the
steam to exhaust by the end of the valve into the steam chest and thence through
the steam chest exhaust port, and at the same time permitting steam to enter from
the valve into the cylinder to drive the piston back, whereby the engine is set and
kept in full motion.

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
3rd May 1882.
"
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. AN IMPROVED BALANCED SLIDE-VALVE" A com-
munication from abroad by William Bright Turman, of Waldron, in the County of
Scott, State of Arkansas, United States of America.
The object of this Invention is to reduce the friction of the valve and conse-
quently the power required to move it, and also to permit of a simultaneous steam
supply and exhaust.
The Invention consists in the combination with the steam chest provided with
supply and exhaust ports, guide strips, and adjustable packing strips, of a valve
provided with an entrance port, interior steam chamber, exhaust ports, an opening
between the exhaust ports and projections on its top and one side, as will be
hereinafter fully described.
Figure 2 is a
Figure 3 is a
Figures 4, 5,
respect to the
In the accompanying Drawings Figuro 1 is a plan of the improved valve in
position on a steam chest, the cover of the chest being removed.
longitudinal sectional clevation of the same on line x-x, Figure 1.
transverse sectional elevation of the same on line y-y, Figure 1.
and 6 are similar views showing modifications of the construction in
packings of the valves and arrangement of the steam ports.
A represents the steam chest, &c., designed to be set on the steam cylinder (not
shown) and to have its ports a, a, correspond with those in said cylinder at either
end thereof, whereby steam may be supplied and exhausted. Said chest A is pro-
vided on one side with a steam supply port b and on the opposito side with a steam
exhaust port c, and on the inside of its top or cover along the central line thereof
is fixed a box d, in which is a packing strip f that is adjusted by set screws g, g,
and half elliptic springs h, h, against the valve B to regulate the pressure of the
latter on its seat. On the inside of the exhaust side of the steam chest A. there is
another packing strip k, adjustably held in braces and pressed by set screws m
and half elliptic springs n against the valve B, to hold the latter with any desired
pressure against the steam supply side of the said chest A, to prevent leakage
thereabouts with the said chest A; t, t, are longitudinal ridges on the top and ono
side of the valve B for the packing bars or strips f, k, to bear against.
The valve B has a port o in one side for the entrance of steam, communicating
with its hollow interior p, and this interior chamber p terminates at each end in a
port q in the valve face. Between these ports q the under face of the valve B is
cut away, as shown at 8, to reduce the friction surface upon the valve seat and to
permit the escape of exhaust steam from the steam cylinder when used on the
common three-port valve seat.
The valve rod C is passed through a stuffing box D on one end of the valve
chest A.
Steam is admitted through the valve chest port b into the valve port o, thenco
out of the valve B through a port q into the engine cylinder (not shown) by which
the piston (not shown) is driven to the opposite end of the cylinder, and by the
action of the eccentric (not shown) the valve B is so moved as to arrive at the
same end at or near the same time with the piston, thereby opening the port in
the other end of the cylinder to permit the steam to exhaust by the end of the
valve B into the steam chest A and thence through the steam chest exhaust port c;
and at the same time permitting steam to enter from the valve B into the
cylinder to drive the piston back, whereby the engine is set and kept in full
motion,

page_text: In the modification shown in Figures 4, 5, and 6 the valve B is held and
guided by a frame or cage R fixed within the steam chest A, and the packing
strip on the upper side of the valve is pressed to the valve by set screws g.
passing through a cross bar t, that is secured on frame R. This allows the top of
the chest to be removed without disturbing the valve, and to facilitate access to
the valve the top and one side of the steam chest are formed in one piece for
removal at once.
The exhaust port c in the chest is placed in the same side as the steam port b.
The valve is also fitted at one side with a packing strip h, set up by a set screw g¹
tapped through a cross bar t' of frame R. Both strips f, h, serve as guides for the
valve, and the valve is formed with raised edges or flanges s' that take upon the
edges of the strips. Beneath the strips f. h, the valve is grooved to receive
packings l, m. The steam from the middle cavity p has access to the back of
strips f, h, by openings e, w, and there are also openings i that admit steam behind
the packings l, m, or there may be springs inserted behind the packings l, m, to
force them against the strips f, h.
Having described the nature of the said Invention and the manner of performing
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 a slide valve the combination with the steam chest A provided with
the supply and exhaust ports b, c, the guide d, 1, and the adjustable packing
strips f, k, on its top and exhaust side of the valve B provided with the entrance
port o, interior steam chamber p, the exhaust ports q, the opening 8, and the ridges
or projections t, substantially-as-and-for-the-purpose set forth.
2nd. The cage or frame R combined with the valve B, substantially as shown
and described.
3rd. The combination of cage R, provided with cross strips t, t', and set
screws g, g', the packing strips f, h, and valve B, substantially as described.
4th. The packing l, m, combined with valve B, and packing strips f, h,
substantially as shown and described.
5th. The valve B, provided with packings l, m, set in recesses in combination
with the supporting guide strips f, h, substantially as specified.
6th. The valve B provided with packing strips f, h, and formed with internal
steam cavity p and passages e, w, substantially as described.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Third day of May, A.D. Eighteen hundred and
eighty-two.