An Improved Balanced Slide-valve for Steam Engines.
Year: 1890

page_text: Date of Application, 12th Aug., 1890
Complete Specification Left. 5th Nov. 1890-4ccented 6th Dec.
1890
PROVISIONAL SPECIFICATION.
An Improved Balanced Slide-valve for Steam Engines.
I, OSCAR LUCIAN WARD of Eagle, in the County of Cass, and State of Nebraska,
United States of America, Machinist, do hereby declare the nature of this invention
to be as follows:-
This invention relates to an improved balanced slide valve for steam engines.
The invention consists in a valve which fits in the steam chest and has through
passages for the steam which intersect one another. One of these passages is
always open to the steam inlet while the other, which serves to distribute the
steam to the cylinder, is brought alternately into communication with the cylinder
ports.
In order to equalise the pressure on the valve, the cylinder communicates with the
steam chest by pipes which open into the steam chest at points opposite the cylinder
ports.
COMPLETE SPECIFICATION.
An Improved Balanced Slide-valve for Steam Engines.
I. OSCAR LUCIAN WARD of Eagle, in the County of Cass, and State of Nebraska,
United States of America, Machinist, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
The object of the invention is to provide a balanced slide valve for steam engines,
and will be described with reference to the accompanying drawings wherein Figure 1.
is a plan view of a steam engine provided with the improvement: Figure 2 is a
transverse section of the cylinder and valve box, on line - Figure 1; Figure 3
is a sectional plan view of the same on line y-y Figure 2; Figure 4 is a sectional
elevation of the same, on line == Figure 3 and Figure 5 is a perspective view of
the slide valve. Similar letters of reference indicate corresponding parts in all the
figures.
The invention consists essentially of the slide valve F which is provided with inter-
secting slots or passages c and d B is the cylinder, from the ends of which lead the
two inlet ports a and b opening into the steam chest E in which is fitted to slide the
valve F. The vertical passage of the slide valve F connects at its upper end, at all
times, with the steam inlet pipe G while the transverse slot d which intersects the slots c
at right angles is connected alternately with the steam inlet ports a and b. The
steam chest E is provided near each end with the exhaust ports e and fand the ends
of the cylinder B are connected with the steam chest E by pipes H and I respectively
opening into the said steam chest opposite the respective ports a and b.
The operation is as follows-When the piston C and the valve Fare in the position
shewn in Figure 3, live steam passes through the inlet pipe G into the vertical
slot c from which it passes to the top and bottom of the slide valve exerting an equal
pressure thereon. It also passes into the transverse slot d so as to exert a pressure
at each side, thus completely balancing the valve so that it only rests by its own weight
on the bottom of the steam chest [E. The steam passing into the passages c and d
passes from the latter passage through the inlet port a into the outer end of the
[Price 6dl

page_text: cylinder B and exerts its pressure against the piston C. The steam in the inner end
of the cylinder B now exhausts through the port into the steam chest E which is
provided with the exhaust port through which the steam escapes. When the piston C
nears the end of its inward stroke, the position of the valve is changed that is, it
moves inward so that communication of passage d with port a is cut off and com-
munication of passage d with inlet is established, so that steam passing into the
slots c and d enters the inner end of the cylinder through port while the exhaust
steam in the outer end of the cylinder B passes away through port a to the outer end
of the steam chest E and out through the exhaust port e.
It will be seen that, during the time the steam cuts off either the port a or bat
the ends of the valve F, pressure is exerted through the respective inlet port a or b
against the cutting-off end of the valve F by the expanding steam in the cylinder
but this pressure against the valve is counterbalanced by the steam in the cylinder
passing through its respective pipe Hor and pressing against the cutting-off end
of the valve F opposite the said port a or b, as the case may be. Thus the valve F
is at all times completely balanced so that the wear is reduced to a minimum.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. A slide valve provided with a passage extending through it from top to bottom
and with a second passage extending through it from side to side and intersecting
the first named passage, substantially as described.
2. The combination, with a cylinder provided with inlet ports and a steam chest
into which said ports open, of a slide valve in the steam chest provided with a
passage extending through it from top to bottom and registering at all times with the
steam inlet of the steam chest and provided also with a second passage extending
through it from side to side and intersecting the first named passage, said second
passage alternately registering with the cylinder ports, substantially as shewn and
described.
3. The combination, with a cylinder provided with inlet ports, of a steam chest
held on the said cylinder and into which said ports open, a slide valve fitted to slide
in said steam chest and pipes connecting the ends of said cylinder with the steam
chest opposite the entrance of said inlet ports to equalise the cylinder pressure on the
slide valve when the ports are cut off, substantially as shewn and described.
4. The combination, with a cylinder provided with inlet ports and a steami chest
into which said ports open, of a slide valve in the steam chest having intersecting
passages or slots extending through it at right angles to each other and pipes con-
necting the ends of the cylinder with the steam chest opposite the inlet ports of said
cylinder, substantially as shewn and described.
Dated this 5th day of November 1890.